Abstract:
A delivery device for the administration of nutrients, drugs, vitamins, trace elements and the like to a ruminant. The device embodies a thermal expanding polymer material which, when heated by the animal&#39;s body heat functions as an internal energy source for controllably expelling the beneficial agents from the device over extended period of time of up to 200 days. The device is of a size and shape that can be introduced into the ruminant via the esophagus and is of a density such that the device will be retained within the reticulo-rumen of the animal for the effective controlled release of the beneficial agents to the animal.

Description:
BACKGROUND OF THE INVENTION 
     This is Continuation-in-Part of application Ser. No. 08/919,147, filed Aug. 27, 1997 U.S. Pat. No. 5,961,492. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to fluid delivery devices. More particularly, the invention concerns a device for the delivery of beneficial agents to ruminants. 
     DESCRIPTION OF THE PRIOR ART 
     It has long been recognized that the delivery of various types of nutrients, drugs, dietary supplements and trace elements for grazing animals, such as sheep and cattle is highly beneficial to the well being and growth of the animal. By way of example, delivery to the grazing animal of various types of antiparasitics can be used to control mange mites, sucking lice, cattle grubs, fly larva, ticks and the like. Similarly, delivery of anti-bacterials such as sulphonamides has proven effective for disease control. In like manner, the delivery of monesin sodium as an anti-bacterial agent has proven effective as a growth promotion in cattle and sheep and the delivery of S-methoprene has been shown to be effective to control pupa of the horn fly in the manure pat. 
     Commonly, grazing animals such as cattle and sheep are turned out in the spring to spend much of the spring, summer and autumn season grazing the open range. With such animals the periodic administration of drugs is complicated by the need to retrieve the animal and then, after retrieval, to effectively administer the nutrient or drug to the animal. For example, one of the principal problems involved in the control of livestock pests has not been the unavailability of effective toxicans, instead it is the relatively short duration of effectiveness of the available compounds due to photodecomposition, evaporation, and absorption of the materials, and due to mechanical losses caused by rubbing of the animal, muscular contractions and the like. Additionally, repeated treatment of livestock is expensive in terms of both labor and insecticides. To compensate for the rapid degradation of the pesticides on animals, the producer must apply larger quantities than are necessary for control of the immediate population if toxic levels are to be maintained for any length of time. Such a practice is wasteful of insecticides, results in greater contamination to the environment and increases the probability of toxicity to animals and the residues in animal products. 
     In light of the foregoing, for many years, it has been an objective of the industry to develop techniques that would make it possible to maintain the minimum effective level of toxicans in livestock over an extended period and thereby increase the efficiency and safety of livestock pest control. Additionally, the cumbersome and labor intensive process of introducing any drug, medicament or other substance into the daily food supply, which is ingested orally by the ruminant, provides little or no assurance that the required amount of agent will have been administered as food intake will vary with each feeding. The use of a controlled-release drug delivery device is an attractive alternative because such an approach has the significant advantage of providing the animal with nutrients and medicaments, which will be released in a controlled manner into the body over a period of time. 
     It is known that the rumen is a suitable site for the administration of drugs to a ruminant. The drug formulation can be injected directly into the rumen through the flank of the animal. Alternatively, a controlled release drug delivery device can be introduced via the mouth of the animal in which case it is desirable for the device to be retained within the reticulo-rumen for controlled release of the drug formulation thereafter. One method of retaining the device within the rumen is to arrange for its geometry to alter once it is in the rumen. For example, wings extended laterally from the main body of the device can retard or prevent regurgitation thereof by the animal. Alternatively, the device may be made sufficiently dense for it to be retained in the rumen simply by the force of gravity. For example, prior art experimentation has shown that retention in the rumen can be achieved by providing a device having an overall device density greater than 2.0. 
     The prior art drug delivery devices for use in rumens typically fall into the classes of erodible devices, reservoir devices, osmotic devices, and pulsatile devices. Erodible devices are designed to dissolve or abraid as a result of solutions within the rumen or due to mechanical action of the rumen. Exemplary of one prior art erodible system is that described in U.S. Pat. No. 3,056,724 issued to H. R. Marsten. Marsten discloses an erodible bolus, which is, provided in the form of a pellet containing cobalt oxide and other diluents that function to produce a product that releases cobalt to the animal for the full grazing season. Another example of a prior art erodible bolus is that described in U.S. Pat. No. 4,166,107 issued to Miller et al. Miller et al discloses a sustained release bolus containing compositions of insect regulators to control the larval activity of arthropods in the manure of livestock. 
     Exemplary of a prior art reservoir type device is the device described in U.S. Pat. No. 4,959,218 issued to Eckenhoff et al. This patent describes a delivery device comprising a housing having an internal space, a beneficial agent in the space, expandable means in the space for causing the beneficial agent to be delivered from the device and means in the space for shielding the beneficial agent from fluid. An earlier Eckenhoff et al U.S. Pat. No. 4,595,583 discloses a somewhat similar reservoir device comprising a semipermeable housing defining an internal space, a dense member in the space, a heat responsive composition containing a beneficial agent in the space, an expandable member in the space, and a passageway in the semipermeable housing for delivering the beneficial agent from the dispensing device. The heat-responsive composition comprises a heat sensitive, hydrophilic or hydrophobic material that exhibits solid-ike properties at room temperature and exhibits a melting point that approximates mammalian body temperatures of 37 degrees centigrade. When administered to the ruminant, this heat responsive composition, which contains the beneficial agent, is heated by the animal&#39;s body and becomes liquid through phase change, thus allowing it to flow outward of the device. 
     The prior art osmotic devices take several forms. One such device is described in U.S. Pat. No. 3,845,770 issued to Theeuwes et al. This device comprises a wall surrounding and forming a compartment for containing a useful composition of matter and has a passageway for dispensing the composition. The wall is comprised, in at least a part, of a material permeable to an external fluid. The composition is soluble in the fluid and exhibits an osmotic pressure gradient against the fluid or the composition has limited solubility and is admixed with an osmotically effective compound soluble in the fluid that exhibits an osmotic pressure gradient against the fluid. In operation, the composition is dispensed from the device by fluid permeating into the compartment producing a solution of the soluble composition or a solution of the osmotically effective compound containing the composition, which solution in either operation is released through the passageway to the exterior of the device at a rate controlled by the permeability of the wall and the osmotic pressure gradient across the wall of the device. 
     Pulsatile systems consist of systems which release multiple doses at preprogrammed intervals. The advantages of these systems are that they tend to better mimic prior art methods of administering multiple doses of immediate release products given at specific time intervals. Exemplary of one form of prior art pulsatile system is that described in U.S. Pat. No. 4,381,780 issued to Holloway. Holloway describes a system consisting of a series of degradable partitions that form compartments within a body. The partitions are made from cellulosic materials that degrade in the rumen thus releasing the drug successively from the compartments. The drug dosage is controlled via the composition or each drug compartment and by the thickness and composition of the degradable partitions. 
     The principal drawbacks of the prior art delivery devices for use in ruminants include difficulty of use, lack of reliability overtime and the inability to deliver precisely controlled doses over extended periods of time. Additionally, unlike devices of the present invention, the prior art devices cannot be filled in the field. It is these drawbacks that the present invention seeks to overcome by providing an easy to use and highly reliable device for precisely delivering various beneficial agents over long periods of time. The devices of the present invention uniquely embody a novel, thermal expanding polymer material, such as a heat expandable gel, that acts as an internal stored energy source for delivering the beneficial agents contained within the device to the animal at a precisely controlled rate over time. This unique stored energy source is more completely described in copending U.S. Ser. No. 08/919,147, which application is hereby incorporated by reference as though fully set forth herein. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a technically advanced delivery apparatus for the administration of nutrients, drugs, vitamins, trace elements and the like (hereinafter beneficial agents) to a ruminant. More particularly, it is an object of the invention to provide a self-contained dispensing apparatus of such a character that embodies a novel, thermal expanding polymer material which uniquely functions as an internal energy source for controllably expelling the beneficial agents from the device. 
     Another object of the invention is to provide a delivery apparatus of the character described which can conveniently be used for precise infusion of beneficial agents to ruminants such as cattle and sheep over extended periods of time of up to 200 days. 
     Another object of the invention is to provide a novel dispensing device that can administer a predetermined regimen for a particular time period and one which requires intervention only for initiation of the regimen. 
     Another object of the invention is to provide an improved self-contained dispensing device which will permit high concentration of active agents to be contained therein which agents will not exhibit a tendency to have their potency decreased by a chemical breakdown. 
     Another object of the invention is to provide a novel delivery apparatus of the character described in the preceding paragraphs which can be effectively used to administer to ruminants beneficial agents including anti-parasitics, anti-bacterials, growth hormones anthelmintics and a variety of trace elements such as cobalt. 
     Another object of the invention is to provide a novel delivery apparatus of the class described which is of a size that can be introduced into the ruminant via the esophagus and is of a density such that the device will be retained within the reticulo-rumen for controlled release of the beneficial agents over long periods of time. 
     Another object of the invention is to provide an apparatus of the character described in the preceding paragraphs which embodies as its stored energy source a gel, which is a soft, pliable, semi-solid, heat expandable mass that is heated by the ruminant&#39;s body temperature in a manner to controllably expel fluids from the device over substantial periods of time. 
     Another object of the invention is to provide an apparatus as described in which the heat-expandable mass is specifically tailored to provide precise, predictable, protocol delivery of the beneficial agents stored within the reservoir of the device. 
     Another object of the invention is to provide an apparatus of the class described which is durable, highly reliable in use and one that will not be damaged by muscular contractions or rubbing by the animal. 
     Another object of the invention is to provide a delivery apparatus of the character described which, due to its unique construction, can be manufactured inexpensively in large volume by automated machinery. 
     Another object of the invention is to provide a dispensing apparatus for dispensing to the animal a modified delivery device. More particularly, it is an object of the invention to provide a novel dispensing apparatus that enables the expeditious insertion of the delivery device into the throat of the animal until the modified delivery device is disposed behind the back of the tongue or even deeper into the animal&#39;s throat. 
     Another object of the invention is to provide a dispensing apparatus of the character described in the preceding paragraph which is of a simple design, is easy to use and is extremely durable and reliable in operation. 
     Another object of the invention is to provide a dispensing apparatus of the character described in the preceding paragraph which can be filled with a selected beneficial agent in the field prior to dispensing to the animal. 
     Another object of the invention is to provide a dispensing apparatus of the character described in the preceding paragraph which can be filled in a sterile manner with a selected beneficial agent. More specifically, the dispensing apparatus may be filled by means of a novel filling device that enables the convenient handling of the beneficial agent in discrete vials prior to the filling step. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a generally perspective view of one form of the delivery device of the invention for the delivery of beneficial agents to ruminants. 
     FIG. 2 is an enlarged front-elevational view of the fluid delivery device shown in FIG.  1 . 
     FIG. 3 is a cross-sectional view taken along lines  3 — 3  of FIG.  2 . 
     FIG. 4 is a generally perspective, exploded view of the delivery device shown in FIG.  3 . 
     FIG. 5 is a generally perspective rear view of the forward portion of the delivery device as viewed along lines  5 — 5  of FIG.  4 . 
     FIG. 6 is an enlarged, cross-sectional view of the area designated in FIG. 3 by the numeral  6 . 
     FIG. 7 is a rear view of the slit septum of the device, which forms a part of the fill means of the invention. 
     FIG. 7A is a cross-sectional view taken along lines  7 A— 7 A of FIG.  7 . 
     FIG. 8 is a front view of the septum housing component of the device. 
     FIG. 9 is a cross-sectional view taken along lines  9 — 9  of FIG.  8 . 
     FIG. 10 is a view taken along lines  10 — 10  of FIG.  9 . 
     FIG. 11 is a front view of one of the manifold components of the device. 
     FIG. 12 is a cross-sectional view taken along lines  12 — 12  of FIG.  11 . 
     FIG. 13 is a front view of the other of the manifold components of the device. 
     FIG. 14 is a cross-sectional view taken along lines  14 — 14  of FIG.  13 . 
     FIG. 15 is a front view of the elastomeric reservoir defining member of the device. 
     FIG. 16 is a cross-sectional view taken along lines  16 — 16  of FIG.  15 . 
     FIG. 17 is a front view of the reservoir retaining ring of the device. 
     FIG. 18 is a cross-sectional view taken along lines  18 — 18  of FIG.  17 . 
     FIG. 19 is a side-elevational, cross-sectional view of the thermal expanding component of the device. 
     FIG. 20 is a side-elevational, cross-sectional view of the housing component of the device of the invention. 
     FIG. 21 generally perspective view of an alternate form of the delivery device of the invention for the delivery of beneficial agents to ruminants. 
     FIG. 22 is a generally perspective, exploded view of the delivery device shown in FIG.  21 . 
     FIG. 23 is a generally perspective rear view of the forward portion of the delivery device as viewed along lines  23 — 23  of FIG.  22 . 
     FIG. 24 is a front view of the base assembly of the embodiment shown in FIG.  21 . 
     FIG. 25 is a cross-sectional view taken along lines  25 — 25  of FIG.  24 . 
     FIG. 26 is an enlarged, cross-sectional view of the area designated in FIG. 25 by the numeral  26 . 
     FIG. 27 is an enlarged, cross-sectional view of the area designated in FIG. 25 by the numeral  27 . 
     FIG. 28 is a cross-sectional view taken along lines  28 — 28  of FIG.  25 . 
     FIG. 29 is a front view of the cover assembly of the device. 
     FIG. 30 is a cross-sectional view taken along lines  30 — 30  of FIG.  29 . 
     FIG. 31 is a generally perspective view of still another form of the invention. 
     FIG. 31A is a generally perspective exploded view of the device shown in FIG.  31 . 
     FIG. 32 is a generally perspective rear view of the forward cover portion of the delivery device as viewed along lines  32 — 32  of FIG. 31 
     FIG. 33 is an enlarged, cross-sectional view of the device illustrated in FIG.  31 . 
     FIG. 33A is a greatly enlarged, cross-sectional view of the area designated in FIG. 33 as  33 A. 
     FIG. 34 is a cross-sectional view taken along lines  34 — 34  of FIG.  33 . 
     FIG. 35 is a cross-sectional view taken along lines  35 — 35  of FIG.  33 . 
     FIG. 36 is an enlarged, cross-sectional view taken along lines  36 — 36  of FIG.  33 . 
     FIG. 37 is a greatly enlarged view taken along lines  37 — 37  of FIG.  33 . 
     FIG. 38 is a greatly enlarged, cross-sectional view taken along lines  38 — 38  of FIG.  33 . 
     FIG. 39 is an enlarged, generally perspective front view of the vent control element of the delivery device of the invention. 
     FIG. 40 is an enlarged, generally perspective rear view of the vent control element shown in FIG.  39 . 
     FIG. 41 is a cross-sectional, fragmentary view of yet another embodiment of the invention having a somewhat different type of vent control means. 
     FIG. 42 is a fragmentary front elevational view of the device shown in FIG.  41 . 
     FIG. 43 is a side-elevational, cross-sectional view of the assemblage shown in FIG.  41 . 
     FIG. 44 is an enlarged, fragmentary, cross-sectional view of the portion of the device shown in FIG. 43 with the fill assembly removed. 
     FIG. 45 is an enlarged view taken along lines  45 — 45  of FIG.  44 . 
     FIG. 46 is an enlarged, cross-sectional view of the vent control means for controlling the flow of gases through the vent passageway of the base assembly. 
     FIG. 47 is a cross-sectional view taken along lines  47 — 47  of FIG.  46 . 
     FIG. 48 is an enlarged cross-sectional view taken along lines  48 — 48  of FIG.  46 . 
     FIG. 49 is a cross-sectional view similar to FIG. 48 but showing the vent control element in a locked position. 
     FIG. 50 is a generally perspective rear view of the vent control element. 
     FIG. 51 is a generally perspective view of the device shown in FIG. 41 mated with an alternate form of reservoir fill assembly which comprises a dual vial system and which can be coupled with the base assembly to fill the device reservoir. 
     FIG. 52 is a generally perspective, exploded view of the dual vial reservoir fill assembly shown in FIG.  51 . 
     FIG. 53 is a generally perspective view of one of the vials of the assembly shown in FIG. 52 partly broken away to show internal construction. 
     FIG. 54 is a side-elevational, cross-sectional view of the assembly shown in FIG.  51 . 
     FIG. 55 is a generally perspective view of the base assembly of an alternate form of delivery device. 
     FIG. 56 is a generally perspective, exploded view of the cover assembly of the alternate form of delivery device shown in FIG.  55 . 
     FIG. 57 is a top plan view of the delivery device partly broken away to show the bayonet-type connector means of the device for interconnecting the cover assembly with the base assembly. 
     FIG. 58 is a cross-sectional view taken along lines  58 — 58  of FIG.  57 . 
     FIG. 59 is a cross-sectional view taken along lines  59 — 59  of FIG.  57 . 
     FIG. 60 is a cross-sectional view similar to FIG. 59 but showing the position of the components of the device after the cover assembly has been rotatably coupled with the base assembly. 
     FIG. 61 is a cross-sectional view of the vent control member of this latest form of the invention 
     FIG. 62 is a view taken along lines  62 — 62  of FIG.  61 . 
     FIG. 63 is a fragmentary, side-elevational, cross-sectional view of an alternate form of the delivery device of the invention having a different type of vent closure means and including gel filling means for filling the device with gel in the field. 
     FIG. 64 is a cross-sectional view taken along lines  64 — 64  of FIG.  63 . 
     FIG. 65 is a cross-sectional view taken along lines  65 — 65  of FIG.  63 . 
     FIG. 66 is a cross-sectional view similar to FIG. 65, but showing the vent closure means rotated to a vent closed position. 
     FIG. 67 is a cross-sectional view taken along lines  67 — 67  of FIG.  63 . 
     FIG. 68 is a generally perspective, bottom view of the cover subassembly of this latest embodiment of the invention. 
     FIG. 69 is a generally perspective view of the vent closure control member of the invention. 
     FIG. 70 is a fragmentary, side-elevational, cross-sectional view of a portion of the delivery device of the invention that is specially adapted for use with dispensing apparatus for use in administering the delivery device to the animal. 
     FIG. 71 is a fragmentary, side-elevational, cross-sectional view showing the modified delivery device of FIG. 70 interconnected with a hand-operated dispensing apparatus. 
     FIG. 72 is a cross-sectional view taken along lines  72 — 72  of FIG.  71 . 
     FIG. 73 is a cross-sectional view taken along lines  73 — 73  of FIG.  71 . 
     FIG. 74 is a foreshortened, cross-sectional view similar to FIG. 71 but showing the hand-operated dispensing apparatus separated from the fluid delivery device. 
     FIG. 75 is a generally perspective, exploded view of the dispensing apparatus shown in FIG.  74 . 
     FIG. 76 is a side-elevational, cross-sectional view of an alternate form of dispensing apparatus of the invention shown interconnected with an alternate form of modified delivery device. 
     FIG. 77 is a cross-sectional view taken along lines  77 — 77  of FIG.  76 . 
     FIG. 78 is a cross-sectional view taken along lines  78 — 78  of FIG.  76 . 
     FIG. 79 is greatly enlarged, fragmentary, side-elevational, cross-sectional view of the connector portion of the dispensing device shown interconnected with the modified delivery device. 
     FIG. 80 is a generally perspective, exploded view of the dispensing apparatus of this latest form of the invention. 
     FIG. 81 is a side-elevational, cross-sectional view similar to FIG. 76, but showing the dispensing apparatus separated from the modified delivery device. 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring to the drawings and particularly to FIGS. 1 through 4, one form of the apparatus of the invention for use in administering beneficial agents to a ruminant is there shown and generally designated by the numeral  40 . As best seen by referring to FIGS. 1 and 3, this embodiment of the invention comprises a generally egg-shaped housing  41  which includes a base assembly  42  and a cover assembly  44 . The device has the novel shape illustrated in FIG. 1 to enable it to be conveniently introduced into the rumen through the mouth of the ruminant. 
     Formed within an internal chamber  43   a  of a base component  43  of base assembly  42 , is a fluid reservoir  46  for containing the beneficial agent to be delivered to the ruminant (FIG.  3 ). Fluid reservoir  46  is formed by an elastomeric distendable member  48  which, in a manner presently to be described, is distended into the configuration shown in FIG. 3, by the introduction of the beneficial agent into the device via the fill means of the invention. 
     Comprising an extremely important aspect of the apparatus of the present invention is a heat-expandable means, which is carried within internal chamber  43   a . The heat expandable means functions to controllably urge fluids contained within reservoir  46  to flow outwardly into the rumen of the ruminant through the delivery means of the invention which includes an outlet  50  formed in housing  41 . The heat-expandable means is here provided in the form of a thermal expandable polymer mass  52  which is contained within chamber  43   a  in the manner best seen in FIG.  3 . Expandable mass  52  can take several forms, but a particularly attractive form for devices of the present invention comprises a semisolid form such as a gel. Unlike a liquid, which can offer no permanent resistance to change in shape and must be constrained within some type of container, expandable mass  52  is of a semisolid form which can advantageously be handled without external containment under ambient manufacturing conditions. 
     From a technical viewpoint, gels are often characterized as soft solids, which reside in a state between a liquid and a solid state. Frequently gels comprise a cross-linked network of long polymer molecules with liquid molecules trapped within the network. Many gels known in the prior art not only are capable of significantly large volume change in response to stimulus (phase-transition gels), but also exhibit physical characteristics that enable them to closely conform to the shape of an adjacent member such as a distendable membrane. Such gels are ideally suited as a stored energy means for fluid delivery devices of the character described hereinafter and also of the character described in incorporated-by-reference application Ser. No. 09/919,147. 
     Phase transition gels best suited for use in constructing the heat expandable means of the present invention are gels which exhibit a large volume change at a given phase-transition condition. Unlike liquids, which exhibit a fixed temperature for state of vaporization to a known volume and with such vaporization point changing as a function of ambient pressure, the phase-transition gels in this invention are multicomponent polymers which can be made to respond with various volume changes to a singular external temperature stimuli. Advantageously, the difference in volume between the expanded phase of these phase-transitions gels and the contracted phase thereof can be orders of magnitude. Examples of suitable phase-transition gels are disclosed in Tanka et al, U.S. Pat. Nos. 4,732,930; Re-35068 and 5,403,893, and Schiller et al, WO 96/02276. 
     Turning particularly to FIG. 3, it is to be noted that a generally cylindrically shaped fill tube  56  having inlet and outlet ports  58  extends into chamber  43   a . Fill tube  56  cooperates with elastomeric member  48  to form reservoir  46  when, as previously mentioned, the beneficial agent is introduced into the fill tube  56  by the novel fill means of the invention. With the construction shown in FIG. 3, when the heat expandable mass  52  is heated by the body heat of the ruminant, it will expand pand and act upon distendable member  48  in a manner to tend to return the member toward its starting configuration and to controllably force the fluid “F”, which is contained within the reservoir  46 , outwardly of the device, through the delivery means, and into the rumen of the animal. It is to be noted that as member  48  moves toward its starting configuration (see FIGS.  4  and  16 ), it will closely conform to the shape of the fill tube  56  as the heat expandable mass  52  expands thereby causing a complete and controlled expelling of fluid from reservoir  46  through the fluid outlets of the fill tube  56  and then into the delivery means of the apparatus, the details of construction of which will presently be described. 
     Referring particularly to FIGS. 3,  4 , and  16  elastomeric member  48  includes a body portion  48   a , a flange portion  48   b  and a neck portion  48   c . As shown in the drawings, a flange portion  48   b  includes a circumferentially extending sealing protuberance  48   d . Member  48  is held in position within chamber  43   a  by means of a retaining ring  64  which is received within the open end of base member  43  in the manner best seen in FIG.  3 . As best seen in FIGS. 4,  17  and  18  retaining ring  64  includes a central opening  64   a  which closely receives the neck portion  48   c  of elastomeric member  48  and functions to maintain the neck portion in sealing engagement with the outer wall of fill tube  56  (FIG.  3 ). Fill tube  56  is, in turn, held in position within chamber  43   a  by a first manifold component  66  which is disposed between base  43  and a cover  45  that comprises a part of cover assembly  44 . Manifold component  66  includes a skirt-like portion  66   a  which is closely received over a reduced diameter flange  43   b  of base  43  (see also FIGS.  13  and  14 ). 
     When the manifold component  66  is disposed in engagement with base  43 , in the manner shown in FIG. 3, flange portion  48   b  of distendable member  48  is securely clamped between the inner face  66   b  of manifold component  66  and the outer face of retaining ring  64  with protuberance  48   d  being maintained in sealable engagement within a circumferentially extending groove  66   c  formed in manifold component  66 . As indicated in FIGS. 3 and 14, manifold component  66  is provided with a fill passageway  70  which is in communication with the interior of fill tube  56  and is also provided with a delivery passageway  72  that is also in communication with the interior of fill tube  56 . Disposed in engagement with manifold  66  is a second manifold  74  which is interconnected with cover  45  by a connector means shown here as a connector component  76 . More specifically, connector component  76 , which is connected to manifold  74 , includes a pair of circumferentially spaced slots  76   a  (see also FIGS. 8 and 9) which lockably receive a pair of circumferentially spaced locking ears  45   a  provided on an inwardly extending neck portion  45   b  formed on cover component  45 . Upon relative rotation between cover component  45  and connector component  76 , the parts will be securely interconnected and maintained in sealed engagement by elastomeric O-rings  75  and  77  (FIG.  3 ). Second manifold  74  also includes an inlet passageway  74   a  that is in communication with inlet passageway  70  of first manifold  66  in the manner shown in FIG.  3 . Second manifold  74  further includes first and second counterbores  74   b  and  74   c  respectively. Counterbores  74   b  and  74   c  function to support a check valve  78  which is of the configuration best seen in FIGS. 3 and 4. Check valve  78  forms a part of the flow control means for controlling fluid flow from the inlet of the device to fill tube  56  via the fill passageways  70  and  74   a  formed in manifolds  66  and  74  respectively. Check valve  78  permits fluid flow inwardly of the device via an inlet passageway  76   b  provided in connector component  76  but prevents fluid flow in the opposite direction. Disposed proximate flow passageway  76   b  is a slit septum  80 , which comprises a part of the fill means of the invention. Septum  80  is held in position by retainer means shown here as a retainer sleeve  82 . Retainer sleeve  82  has a tapered inner wall  82   a  which engages septum  80  and sealably holds the septum in position within member  82  when member  82  is secured to connector component  76 . Septum  80  is accessible by a piercing cannula of a syringe device when cover  45  is disconnected from connector  76 . The base and cover components of the fluid delivery device can be constructed from the cover materials described in incorporated by reference Ser. No. 08/919,147. Ser. No. 08/919,147 should also be consulted for an identification of the various distendable membrane materials that can be used to construct distendable member  48  and for a description of the various coatings that can be applied thereto. 
     With the construction thus described, fluid can be introduced via septum  80  into inlet passageway  76   b  of connector  76 , past check valve  78 , into fill passageway  74   a  of manifold  74 , into passageway  70  of manifold  66  and then into the interior  56   a  of fill tube  56 . Fluid flowing into fill tube  56  will flow through inlet/outlet ports  58  into pressural engagement with the elastomeric member  48  causing it to distend outwardly from the first configuration shown in FIG. 4 to the second configuration shown in FIG. 3 thereby forming fluid reservoir  46 . With reservoir  46  appropriately filled with the beneficial agent to be delivered to the ruminant, the egg-shaped device of the invention can be inserted into the rumen of the animal through the animal&#39;s mouth. Disposed within an internal chamber defined by the outer wall of base  43  and an inner, dome-shaped wall  84  is a weight  86  having a density such that the overall density of the delivery device will be on the order of 2.0. With this density the device will be effectively retained within the rumen of the ruminant and will not be regurgitated therefrom. Components of the fluid delivery device can be constructed from materials identified in U.S. Pat. No. 5,205,820 issued to one of the present inventors. 
     After the device of the invention has been inserted into the rumen of the animal, the body temperature of the animal will cause the heat expandable gel  52  to expand and act upon distendable member  48  in a manner to cause the member to tend to return to its original starting configuration as shown in FIG. 4 wherein it was in engagement with fill tube  56 . As the heat expandable gel controllably urges distendable member  48  toward its original starting configuration, fluid will be controllably urged through ports  58  of the fill tube and into outlet passageway  72  of manifold component  66 . The fluid under pressure will then flow through a leg  72   a  of passageway  72  and then toward outlet  50  of the device. 
     An important feature of the apparatus of the present invention resides in the flow rate control means comprises, in addition to the heat expandable means or gel  52 , an impedance means which is here shown as a porous impedance frit  88  that is secured within outlet  50 . This important flow rate control means precisely controls the rate of fluid flow from reservoir  46  through outlet  50  of the device and into the rumen of the animal. To appropriately vent to atmosphere any gasses that may be contained within chamber  43   a  and to contain gel  52 , a porous gas vent ring and gel block  90  is provided within a groove  92  formed in retainer ring  64 . Gasses within chamber  43   a  will flow through ring  90  into a passageway  94  formed in retainer ring  64 , into a passageway  96  formed in manifold  66 , into passageway  98  formed in manifold  74  and then into cover component  45  (see also FIG.  6 ). 
     Turning next to FIGS. 21 through 30, an alternate form of the apparatus of the invention for use in administering beneficial agents to a ruminant is there shown and generally designated by the numeral  100 . As best seen by referring to FIGS. 21 and 22, this latest embodiment of the invention is somewhat similar to that shown in FIGS. 1 through 20. Accordingly, like numerals are used in FIGS. 21 through 30 to identify like components. As before, the apparatus comprises a generally egg-shaped housing  101  which includes a base assembly  102  and a cover assembly  104 . Formed within an internal chamber of  103   a  of a base component  103  of base assembly  102 , is a fluid reservoir  46  for containing the beneficial agent to be delivered to the ruminant (FIG.  25 ). Fluid reservoir  46  is formed by an elastomeric distendable member  48 , which as in the earlier described embodiment, is distended into the configuration shown in FIG. 25, by the introduction of the beneficial agent into the device via the fill means of the invention. 
     The apparatus of this latest form of the invention also includes a heat-expandable means, which is carried within a chamber  103   a  and functions to controllably urge fluids contained within reservoir  46  to flow outwardly into the rumen of the ruminant through the delivery means of the invention which includes an outlet  50  formed between manifolds  122  and  112 . The heat-expandable means is once again provided in the form of a thermal expandable polymer mass  108  which is contained within chamber  103   a  in the manner best seen in FIG.  25 . As before, expandable mass  108  can take several forms but, for the reasons previously discussed, a particularly attractive form for devices of this alternate form of the invention is semisolid form such as a gel. Examples of suitable phase-transition gels are disclosed in Tanka et al, U.S. Pat. Nos. 4,732,930; Re-35068 and 5,403,893. 
     Turning particularly to FIGS. 22 and 25, the previously identified fill tube extends into chamber  103   a  and cooperates with elastomeric member  48  to form reservoir  46  when the beneficial agent is introduced into the fill tube  56  by the fill means of the invention. As in the earlier described embodiment, when the heat expandable mass  108  is heated by the body heat of the ruminant, it will expand and act upon distendable member  48  in a manner to tend to return the member toward its starting configuration and to controllably force the fluid “F”, which is contained within the reservoir  46 , outwardly of the device, through the delivery means, and into the rumen of the animal. As in the earlier described form of the invention, as member  48  moves toward its starting configuration (see FIG.  22 ), it will closely conform to the shape of fill tube  56  as the heat expandable mass  108  expands thereby causing a complete and controlled expelling of fluid from reservoir  46  through the fluid outlets of the fill tube  56  and then into the delivery means of the apparatus, the details of construction of which will presently be described. 
     Member  48 , which is of the configuration previously described, is held in position within chamber  103   a  by means of a retaining ring  110  which is of a similar construction to ring  64  and is received within the open end of base member  103  in the manner best seen in FIG.  25 . As best seen in FIGS. 25 and 26 retaining ring  110  includes a central opening  110   a  which closely receives the neck portion  48   c  of elastomeric member  48  and functions to maintain the neck portion in sealing engagement with the outer wall of fill tube  56  (FIG.  25 ). Fill tube  56  is, in turn, held in position within chamber  103   a  by being bonded to first manifold component  112 . Manifold component  112  is somewhat similar in construction to manifold component  66 , but includes a peripheral portion  112   a  which buts up against an edge  103   b  of base  103  (see also FIGS.  26  and  27 ). 
     When the manifold component  112  is disposed in engagement with base  103 , in the manner shown in FIG. 25, flange portion  48   b  of distendable member  48  is securely clamped between the inner face  112   b  of manifold component  112  and the outer face  110   b  of retaining ring  110  with protuberance  48   d  being maintained in sealable engagement within a circumferentially extending groove  112   c  formed in manifold component  112 . As indicated in FIG. 28, manifold component  112  is provided with a fill passageway  116  which is in communication with the interior of fill tube  56  and is also provided with a delivery passageway  120  (FIG. 28) that is also in communication with the interior of fill tube  56 . Disposed in engagement with manifold  112  is a second manifold  122  which is interconnected with cover  105  by the previously described connector means or connector component  76 . More specifically, circumferentially spaced slots  76   a  of connector  76  lockably receive a pair of circumferentially spaced locking ears  105   a  provided on an inwardly extending neck portion  105   b  formed on cover component  105  (see FIG.  30 ). Upon relative rotation between cover component  105  and second manifold  122 , the parts will be securely interconnected and maintained in sealed engagement by elastomeric O-rings  75  and  77 . Second manifold  122  also includes an inlet passageway  122   a  that is in communication with inlet passageway  116  of first manifold  112  in the manner shown in FIG.  28 . Second manifold  122  further includes first and second counterbores  122   b  and  122   c  respectively. Counterbores  122   b  and  122   c  function to support a check valve  78 , which is of the character previously described. As before, valve  78  permits fluid flow inwardly of the device via an inlet passageway  76   b  provided in connector component  76  but prevents fluid flow in the opposite direction. 
     A novel feature of this latest embodiment of the invention is the provision of gel filling means for filling chamber  103   a  in the field with the heat expandable gel  108 . As best seen in FIG. 27, this gel filling means here comprises a fill port  126  formed in manifold  122  and gel filling passageways  128  and  130  formed in first manifold  112  and retaining ring  110  respectively for communication with fill port  126 . Also forming a part of the gel filling means is check valve  132  mounted on retaining ring  110  (FIGS. 25 and 27) which permits gel flow into chamber  103   a  but blocks flow in the opposite direction. Fill port  126  here comprises a luer port to which a fill line with a luer connector can be interconnected. When the port is not in use it can be sealably closed by a luer closure cap  136  (see also FIG.  27 ). 
     The gel filling means further includes an overflow reservoir component  138  which is generally annular in shape and is disposed within chamber  103   a  in the manner shown in FIGS. 25 and 28. The overflow reservoir solves the problem of over filling in the field by providing a suitable catch reservoir to safely accommodate excess gel introduced into the device during field filling. A reservoir cover plate  140  is disposed between retaining ring  110  and gel reservoir component  138  to form a (see FIGS. 22 and 28) gel reservoir  138   a . Plate  140  is provided with a gel overflow pathway  140   a  that is in communication with reservoir  138   a  and an entrance port  140   b  that also communicates with reservoir  138   a  (FIG. 26) and permits overflow gel to enter the reservoir in the manner shown in FIG.  26 . 
     An elastomeric reservoir vent seal  144  is threadably received within a bore  122   d  formed in manifold  122  and functions to prevent gel from flowing through a gas vent  146  formed in manifold  112  (FIG.  26 ). Vent  146  is constructed and arranged so as to permit gases trapped within chamber  103   a  to be vented to atmosphere during the gel filling step. During this filling step gel is forced under pressure into gel fill port  126 , through passageways. 
     Disposed proximate flow passageway  76   b  is a slit septum  80 , which comprises a part of the fill means of the invention. Septum  80  is held in position within a connector  76  by the retainer means or retainer sleeve  82 . Septum  80  is accessible by a piercing cannula of a syringe device when cover  105  is disconnected from connector  76 . 
     With the construction described in the preceding paragraphs, fluid can be introduced via septum  80  into inlet passageway  76   b  of connector  76 , past check valve  78 , into fill passageway  122   a  of manifold  122 , into passageway  116  of manifold  112  and then into the interior  56   a  of fill tube  56 . Fluid flowing into fill tube  56  will flow through inlet/outlet ports  58  into pressural engagement with the elastomeric member  48  causing it to distend outwardly from the first configuration shown in FIG. 22 to the second configuration shown in FIG. 25 thereby forming fluid reservoir  46 . With reservoir  46  appropriately filled with the beneficial agent to be delivered to the ruminant, the egg-shaped device of the invention can be inserted into the rumen of the animal through the animal&#39;s mouth. Disposed within an internal chamber defined by the outer wall of base  103  and an inner, dome-shaped wall  124  (FIG. 25) is the previously described weight  86  which has a density such that the overall density of the delivery device will be on the order of 2.0. With this density the device will be effectively retained within the rumen of the ruminant and will not be regurgitated therefrom. 
     After the device of the invention has been inserted into the rumen of the animal, the body temperature of the animal will cause the heat expandable gel  108  to expand and act upon distendable member  48  in a manner to cause the member to tend to return to its original starting configuration as shown in FIG. 22 wherein it was in engagement with fill tube  56 . As the heat expandable gel controllably urges distendable member  48  toward its original starting configuration, fluid will be controllably urged through ports  58  of the fill tube and into outlet passageway  120  of manifold component  112 . The fluid under pressure will then flow through a leg  120   a  of passageway  120  and then toward outlet  50  of the device. 
     The apparatus of this latest embodiment also includes flow rate control means provided in the form of porous impedance frit  88  that is secured within outlet  50  (FIG.  28 ). As before, the heat expandable gel precisely controls the rate of fluid flow from reservoir  46  through outlet  50  of the device and into the rumen of the animal. 
     Referring next to FIGS. 31 through 40, still another form of the apparatus of the invention for use in administering beneficial agents to a ruminant is there shown and generally designated by the numeral  150 . Once again, this embodiment of the invention is somewhat similar to that shown in FIGS. 1 through 20 and like numerals are used in FIGS. 31 through 40 to identify like components. As in the earlier described embodiments, the apparatus here comprises a generally egg-shaped housing  151  which includes a base assembly  152  and a cover assembly  154 . Formed within an internal chamber of  153   a  of a base component  153  of base assembly  152 , is a fluid reservoir  156  for containing the beneficial agent to be delivered to the ruminant (FIG.  33 ). Fluid reservoir  156  is formed by an elastomeric distendable member  158 , which as in the earlier described embodiment, is distended into the configuration shown in FIG. 33, by the introduction of the beneficial agent into the device via the fill means of the invention. As shown in FIG. 33A, distendable member  158  is of a laminate construction comprising laminates  158   a  and  158   b . Additionally, as shown in FIG. 33A, diffusion barrier coatings are provided on member  158  to achieve desired liquid, gas or vapor permeability characteristics for the membrane assemblage. Examples of diffusion barrier coatings, such as coating  159 , include nitrile rubbers, urethanes, parylene (a family of aromatic thermoplastic polymers), or fluoropolymers (such as, for example, a material sold by DuPont Dow Elastomers, Wilmington, Del. under the name and style of “VITON”). Further, the laminate construction may also be intercoated between the laminates with a coating  161  that will promote the bondability of the laminates. By way of example, liquid crystal polymers such as a material sold by DuPont under the name and style of “ZENITE” can be used for this purpose. In addition to coatings, the distendable member  158  can also be interfacially treated to alter the molecular surface of the membrane. By way of example, corona or plasma treatments can vary the surface tension characteristics of the membrane such that it may increase of decrease its adhesive qualities. 
     The apparatus of this latest form of the invention also includes a heat-expandable means, which is carried within a chamber  153   a  and functions to controllably urge fluids contained within reservoir  156  to flow outwardly into the rumen of the ruminant through the delivery means of the invention which includes a pair of diametrically opposed outlets  160  formed in housing  151  (FIG.  34 ). The heat-expandable means is once again provided in the form of a thermal expandable polymer mass  162  which is contained within chamber  153   a  in the manner best seen in FIG.  33 . As before, expandable mass  162  can take several forms including a semisolid form such as a gel. A weight  163  is disposed within a chamber  163   a  of the base assembly which surrounds chamber  153   a  (FIG.  33 ). 
     Turning particularly to FIGS. 31A and 33, a slightly differently configured fill tube  164  extends into chamber  153   a  and cooperates with elastomeric member  158  to form reservoir  156  when the beneficial agent is introduced into the fill tube by the fill means of the invention. As in the earlier described embodiment, when the heat expandable mass  162  is heated by the body heat of the ruminant, it will expand and act upon distendable member  158  in a manner to tend to return the member toward its starting configuration and to controllably force the fluid “F”, which is contained within the reservoir  156 , outwardly of the device through the delivery means, and into the rumen of the animal. As member  158  moves toward its starting configuration (see FIG.  31 A), it will cause a complete and controlled expelling of fluid from reservoir  156  through the fluid outlets  164   a  of the fill tube  164  and then into the delivery means of the apparatus, the details of construction of which will presently be described. 
     Member  158  is held in position within chamber  153   a  by means of a manifold  168  having a generally cylindrically shaped neck  168   a  that extends into chamber  153   a . The open mouth of elastomeric member  158  is receivable over neck  168   a  and a clamping ring  170  functions to maintain the elastomeric member in sealing engagement with neck  168   a  in the manner shown in FIGS. 33 and 35. Manifold component  168  includes a peripheral portion  169  which butts up against an edge  173   a  of a base member  173  which forms a part of base assembly  152  (see also FIG.  35 ). When the manifold component  168  is disposed in engagement with base member  173 , in the manner shown in FIG. 33, fill tube and elastomeric member  158  protrudes into chamber  153   a  and are surrounded by heat expandable means  162 . As indicated in FIG. 33, manifold component  168  is provided with a fill passageway  174  which is in communication with the interior of fill tube  164  and is also provided with a delivery passageway  176  (FIG. 35) that is also in communication with the interior of fill tube  164 . Passageway  176 , in turn, communicates with a transverse delivery passageway  178  that communicates with outlet ports  160  (see also FIG.  34 ). 
     Disposed in engagement with manifold  168  is a second manifold  180  which is interconnected with a cover component  154   a  of a cover assembly  154  by the previously described connector means or connector component  76 . More specifically, circumferentially spaced slots  76   a  of connector  76  lockably receive a pair of circumferentially spaced locking ears  154   b  provided on an inwardly extending neck portion  154   c  formed on cover component  154   a  (see FIG.  33 ). Upon relative rotation between cover component  154   a  and second manifold  180  to which connector  76  is affixed, the parts will be securely interconnected and maintained in sealed engagement by elastomeric O-ring  77 . Second manifold  180  also includes an inlet passageway  180   a  that is in communication with inlet passageway  174  of first manifold  168  in the manner shown in FIG.  33 . Second manifold  180  further includes first and second counterbores  181  and  183  respectively (see FIG.  35 ). Counterbores  181  and  183  function to support a check valve  78 , which is of the character previously described. As before, valve  78  permits fluid flow inwardly of the device via an inlet passageway  76   b  provided in connector component  76  but prevents fluid flow in the opposite direction. 
     A novel feature of this latest embodiment of the invention is the provision of vent closure means for opening and closing vent passageways  186  and  187  formed in manifolds  168  and  180  respectively (FIGS.  33  and  36 ). These vent passageways are necessary to vent chamber  153   a  during the gel filling step and also during reservoir filling step which causes elastomeric member  158  to expand within chamber  153   a  in the manner shown in FIG.  33 . As best seen in FIGS. 39 and 40, this vent closure means here comprises a control member  190  having a head portion  190   a , a flow control portion  190   b  and a connector  190   c  that extends between and connects portions  190   a  and  190   b . Control member  190  is rotatably carried between manifolds  168  and  180  in the manner shown in FIG. 33 with flow control portion  190   b  disposed intermediate vent passageways  186  and  187 . Flow control portion  190   b  has a through bore  191  that can be aligned with vent passageways  186  and  187  when the control member is rotated from the vent closed position shown in FIG. 36 to a vent open position wherein passageway  191  is aligned with vents  186  and  187 . To rotate member  190 , head portion  190   a  is provided with spanner holes  193  which receive tangs  195  provided on a physician&#39;s key  196  of the character shown in FIG.  31 A. Flow control portion includes stop shoulders  197  which abut the manifold compartments in the manner shown in FIG.  38  and function to control the extent of rotation of the control member. As shown in FIG. 37, indicia provided on housing  151  indicate the open and closed position of the control member. 
     Turning now to FIGS. 41 through 50, still another embodiment of the invention is there shown and generally designated by the numeral  200 . This embodiment of the invention is quite similar to that shown in FIGS. 31 through 40 and like numerals are used in FIGS. 41 through 50 to identify like components. As in the earlier described embodiments, the apparatus here comprises a generally egg-shaped housing similar to that shown in FIG. 33 which includes a slightly different base assembly  202  (FIG. 41) and a cover assembly similar to cover assembly  154 . Formed within an internal chamber of  153   a  of a base component  153  of base assembly  202 , is a fluid reservoir  156  for containing the beneficial agent to be delivered to the ruminant (FIG.  44 ). Fluid reservoir  156  is formed by an elastomeric distendable member  158 , which as in the earlier described embodiment, is distended into the configuration shown in FIG. 44, by the introduction of the beneficial agent into the device via the fill means of the invention. 
     The apparatus of this latest form of the invention also includes a heat-expandable means which is carried within a chamber  153   a  and functions to controllably urge fluids contained within reservoir  156  to flow outwardly into the rumen of the ruminant through the delivery means of the invention which includes a pair of diametrically opposed outlets  160  of the character shown FIG.  34 . The heat-expandable means is once again provided in the form of a thermal expandable polymer mass  162  which is contained within chamber  153   a  in the manner best seen in FIG.  43 . As before, expandable mass  162  can take several forms including a semisolid form such as a gel. A weight  203 , which is disposed within a chamber  205  that surrounds chamber  153   a  once again functions to retain the device within the animal&#39;s rumen. 
     Turning particularly to FIGS. 43 and 44, it can be seen that fill tube  164  extends into chamber  153   a  and cooperates with elastomeric member  158  to form reservoir  156  when the beneficial agent is introduced into the fill tube by the fill means of the invention. As in the earlier described embodiments, when the heat expandable mass  162  is heated by the body heat of the ruminant, it will expand and act upon distendable member  158  in a manner to tend to return the member toward its starting configuration and to controllably force the fluid, which is contained within the reservoir  156 , outwardly of the device, through the delivery means, and into the rumen of the animal. As member  158  moves toward its starting configuration, it will expel fluid from reservoir  156  at a controlled rate through the fluid outlets  164   a  of the fill tube  164  and then into the delivery means of the apparatus, which is of the character previously described. 
     Member  158  is held in position within chamber  153   a  by means of a manifold  204  having a generally cylindrically shaped neck  204   a  that extends into chamber  153   a  (FIG.  44 ). The open mouth  158   a  of elastomeric member  158  is receivable over neck  204   a  and a clamping ring  170  functions to maintain the elastomeric member in sealing engagement with neck  204   a  in the manner shown in FIGS. 43 and 44. Manifold component  204  includes a peripheral portion  205  which butts up against an edge  173   a  of a base member  173  that forms a part of base assembly  152 . When the manifold component  204  is disposed in engagement with base member  173 , in the manner shown in FIG. 43, both the fill tube and elastomeric member protrude into chamber  153   a  and are surrounded by heat expandable means  162 . As indicated in FIG. 44, manifold component  204  is provided with a fill passageway  206  which is in communication with the interior of fill tube  164  and is also provided with a delivery passageway of the character previously described that is also in communication with the interior of fill tube  164 . As before, this passageway communicates with a transverse delivery passageway that, in turn, communicates with outlet ports  160  (see, for example, FIG.  34 ). 
     Disposed in engagement with manifold  204  is a second manifold  208  which can be interconnected with a cover component  154   a  of a cover assembly  154  of the character seen in FIG. 33 by the previously described connector means or connector component  76 . More specifically, circumferentially spaced bayonet type slots  76   a  of connector  76  (FIG. 44) lockably receive a pair of circumferentially spaced locking ears  154   b  provided on an inwardly extending neck portion  154   c  formed on cover component  154   a  (see FIG.  33 ). Upon relative rotation between cover component  154   a  and second manifold  208  to which connector  76  is affixed, the parts will be securely interconnected and maintained in sealed engagement by elastomeric O-ring  77 . Second manifold  208  also includes an inlet passageway  208   a  that is in communication with inlet passageway  206  of first manifold  204  in the manner shown in FIG.  44 . Second manifold  208  further includes first and second counterbores  210  and  212  respectively (see FIG.  44 ), which support check valve  78 , that is of the character previously described. In this latest embodiment of the invention, manifolds  204  and  208  carry a slit septum  214  which can be used to introduce gel  162  into chamber  153   a  via a passageway  216  formed in manifold  204  (FIG.  44 ). Septum  214  is of conventional construction and is pierceable by a cannula of a conventional syringe assembly carrying gel  162 . 
     This latest embodiment of the invention is also provided with novel vent closure means for opening and closing vent passageways  218  and  220  formed in manifolds  204  and  208  respectively (FIGS.  44  and  46 ). Vent passageways  218  and  220  are necessary to vent chamber  153   a  during reservoir filling at which time elastomeric member  158  expands into chamber  153   a . Passageways  218  and  220  also function to vent gases to atmosphere as the gel is heated and expands into space  223  (FIG.  43 ). As best seen in FIGS. 44 through 50, this vent closure means is somewhat similar to that previously described and comprises a control member  224 . As shown in FIG. 50, control member  224  includes a lever arm portion  224   a , a flow control portion  224   b  and a connector  224   c  that extends between and connects portions  224   a  and  224   b . Control member  224  is rotatably carried between manifolds  204  and  208  in the manner shown in FIG. 46 with flow control portion  224   b  disposed intermediate vent passageways  218  and  220 . As indicated in FIG. 47, flow control portion  224   b  has a through bore  225  that can be aligned with vent passageways  218  and  220  when the control member is rotated between a vent closed position shown in FIG. 47 to a vent open position wherein passageway  225  is aligned with vents  218  and  220 . Lever arm portion  224   a  permits easy rotation of the control member from the off position shown in FIG. 48 to the locked position shown in FIG.  49 . An O-ring  227  circumscribes connector shaft  224   c  and sealably connects the control member to manifolds  204  and  208  in the manner best seen in FIG.  46 . As shown in FIG. 45, indicia provided on base assembly  202  indicate the off, vent and lock position of the control member. To locate the control member within the manifold, a locking shoulder  224   d  and a spring locking tab  224   e  are provided on control portion  224   b  (FIG.  50 ). As shown in FIGS. 46 and 47, a hydrophobic vent element  230  is disposed within vent passageway  220 . 
     As best seen in FIGS. 41,  42  and  43 , a fill assembly, generally designated by the numeral  234 , is provided to controllably fill reservoir  156  via check valve  78  and fill passageways  206  and  208 . Fill assembly  234  includes an adapter member  236 , which is of a configuration somewhat similar to that of neck portion  154   c  of cover  154 , and includes circumferentially spaced ears  236   a . Ears  236   a  are receivable within slots  76   a  of base assembly connector  76  so that, upon rotation of the fill assembly relative to the base assembly, the fill assembly can be sealably interconnected to the base assembly. Carried by adapter member  236  is an outwardy extending hollow cannula  238  which is adapted to pierce cannula  80  as the adapter member is coupled with connector  76  in the manner shown in FIG.  43 . Connected to adapter member  236  is an adapter housing  240  having a first open end  240   a  and a second end  240   b . Housed within second end  240   b  is an umbrella type check valve  241  that controls fluid flow toward and away from hollow cannula  238 . Also housed within second end  240   b  is an inwardly extending hollow cannula  243 . 
     Receivable within first open end  240   a  of adapter housing  240  is a container assembly  242 . Container assembly  242  includes a body portion  244  having a fluid chamber  246  (FIG. 43) for containing the fluid to be used to fill reservoir  156 . Chamber  246  has first and second ends  246   a  and  246   b  with first end  246   a  being sealably closed by closure means here provided in the form of a pierceable septum assembly  250 . Septum assembly  250  is held securely in position within body portion  244  by a clamping ring  252 . A plunger  254  is receivable within second end  246   b  and is telescopically movable within chamber  246  from a first location shown in FIG. 43 where it is proximate second open end  246   b  to a second position where it is proximate first end  246   a . The vial or body portion of container subassembly  242  can be constructed from various materials such as glass and plastic. As illustrated in FIGS. 42 and 43, adapter housing  240  has a first open end  240   a  and a second closed end  240   b . Container subassembly  242  is telescopically receivable within open end  240   a  of housing  240  in the manner shown in FIG.  43 . 
     Forming an important part of the fill assembly  234  is pusher means shown here as an elongated pusher rod  258  which functions to move plunger  254  within fluid chamber  246  from the first position to the second position. In the form of the invention shown in the drawings, pusher rod  258  has a first end  258   a  interconnected with a closure wall  260   a  of a pusher housing  260  and an opposite end  258   b  which engages plunger  254  and causes telescopic movement of the plunger within chamber  246  of container subassembly  242  as the pusher means is moved from the extended position shown in FIG. 43 into a container assembly encapsulating position wherein pusher housing  260  substantially encapsulates container assembly  242 . 
     As best seen by referring to FIG. 43, the interior surface  245  of adapter housing  240  cooperates with a spaced-apart inner wall  247  to form an elongated generally annular shaped passageway  249  within which pusher housing  260  is received as the pusher housing is moved toward its container encapsulating position. To expedite insertion of the pusher housing, adapter housing  240  is provided with outwardly extending finger engaging members  262  which can be gripped by the fingers while the palm of the hand urges pusher housing  260  inwardly of passageway  249 . The housing and adapter components of the fill assembly of the invention can be constructed from acrylic, polycarbonate and other similar materials well known to one skilled in the art. 
     Prior to mating the fill assembly with base assembly  202 , a tear away seal tab  266 , which sealably closes the open end of adapter member  236 , is removed (FIG.  42 ). This done, the adapter member can be telescopically inserted into connector  76  causing piercing cannula  238  to pierce septum  80 . As previously mentioned, rotation of the adapter member relative to connector  76  will lockably interconnect fill assembly  234  with base assembly  202  in the manner shown in FIG.  41 . 
     Once a fluid flow path between cannula  238  and fill tube  164  has thusly been established, container subassembly  242  can be inserted into adapter housing  240 . An inward force exerted on pusher housing  260  will then cause pusher rod  258  to move the container assembly  242  forwardly of housing  240  to a position shown in FIG.  43 . In this position, inwardly extending hollow cannula  243  will pierce septum  250  of the container assembly thereby opening fluid communication between chamber  246  of the vial assembly and hollow cannula  238 . As plunger  254  is moved further forwardly by pusher rod  258 , the fluid contained within vial chamber  246  will flow through hollow cannula  243 , past check valve  241 , into hollow cannula  238  and then into fluid reservoir  156  via passageways  206  and  208   a . As the fluid under pressure flows into reservoir  156 , membrane  158  will be distended outwardly in the manner shown in FIG.  44 . Ring  170 , which clamps membrane  158  to neck  204   a  of manifold  204 , functions to seal the membrane against neck  204   a  and thereby prevent leakage of fluid around the perimeter of the mouth of the membrane. During this filling step, the vent control means is in the vent position (FIG. 45) permitting the venting of gases from chamber  153   a  to atmosphere via vent passageways  218  and  220 . Once reservoir  156  is appropriately filled, the vent control means is rotated to the lock position wherein the vent passageways are closed. 
     Turning next to FIGS. 51 through 54, still another form of the fluid delivery apparatus of the invention is there shown and generally designated by the numeral  268 . This apparatus is also similar to the apparatus shown in FIGS. 43 through 50 and like numerals are used in FIGS. 51 through 54 to identify like components. In this latest embodiment of the invention, the base assembly  202  is identical to that previously described. However, in this latest form of the invention, an entirely different dual housing fill assembly is provided. This novel fill assembly, which is generally designated by the numeral  270 , is interconnected with the connector means of the base assembly by a connector adapter member  272  that is of a somewhat similar construction to adapter member  236  and includes circumferentially spaced locking ears  272   a  which are lockably receivable within slots  76   a  of base assembly connector  76 . Unlike the previously described fill assembly  234 , this latest fill assembly comprises first and second, side-by-side fill assemblies generally designated in the drawings by the numerals  274  and  296  respectively. Each of the fill assemblies is interconnected with, and is in fluid communication with, a hollow cannula  278  which is provided on adapter member  272 . In a manner presently to be described, cannula  278  is adapted to pierce septum  80  of the base assembly  202  (FIG.  54 ). 
     Referring particularly to FIGS. 52 and 53, first assembly  274  includes an adapter housing  278  that is of similar construction to adapter housing  240  and is adapted to receive a container or vial assembly  280  which uniquely contains a lyophilized drug  282  that is separated from a reconstituting fluid  284  by a barrier stopper  286  (FIG.  53 ). Lyophilized drug  282  can, by way of example, comprise anti-infectives or various other types of beneficial agents. Vial assembly  280  is telescopically receivable within a pusher housing  288  that is similar to pusher housing  260 . Pusher housing  288  is, in turn, receivable within an annular shaped opening  290  formed within housing  278  of the dual housing  270 . As before, pusher housing  288  includes a pusher member  292  that engages a plunger  294  (FIG. 54) to push it forwardly of the container assembly to cause mixing of the fluid  284  with the lyophilized drug  282 . This novel mixing step will be described more fully in the paragraphs which follow. 
     Second fill assembly  276  includes a housing  296  which accepts a fluid container  298  that includes a fluid chamber  298   a . Container  298  has a first open end  298   b  that is sealably closed by a plunger assembly  300  and a closed second end  298   c . In the manner shown in FIG. 54, container  298  is telescopically receivable within housing  296  of the second fill assembly  276 . Plunger assembly  300  includes a body portion  300   a  and a threaded connector portion  300   b  which can be threadably interconnected with a pusher member  302  provided interiorly of housing  296  in the manner illustrated in FIG.  54 . In this regard, pusher member  302  includes a head portion  302   a  that is internally threaded to receive connector portion  300   b  of plunger assembly  300  (FIG.  54 ). Pusher assembly  302  also includes a hollow cannula  304  that extends into an interior chamber defined by a threaded portion  302   b . With this construction, when plunger assembly  300  is threadably interconnected with pusher member  302  in the manner shown in FIG. 54, hollow cannula  304  will pierce a central wall  307  formed in body  300   a  thereby opening fluid communication between fluid chamber  298   a  and the internal passageway of hollow cannula  304 . An inward pressure exerted on container  298  will then urge the fluid contained within fluid chamber  298   a  to flow into hollow cannula  304  and then into a chamber  308  formed in housing  296  that houses a conventional umbrella check valve  310  (FIG.  54 ). Fluid under pressure will then flow past umbrella valve  310  into passageway  312  formed in adapter  272  and then into the internal passageway of piercing cannula  278 . It is to be understood that the fluid contained within chamber  298   a  can take various forms as, for example, a diluent or a beneficial agent of some type. When the second fill assembly  274  of this latest form of the invention is mated with base assembly  202  in the manner shown in FIG. 54, cannula  278  will pierce septum  80  thereby permitting fluid to flow into reservoir  156  in the manner previously discussed. 
     Considering once again the novel first fill assembly  274  and referring particularly to FIGS. 52,  53 , and  54  container assembly  280  as presented to pusher housing  288  includes a vial  280   a  that is sealed at one end by a plunger  294  and at the other end by a pierceable septum  314  (FIGS.  53  and  54 ). Formed intermediate the ends of vial  280   a  is a raised outer wall portion  280   b  which permits fluid  284  to bypass barrier stopper  286  as the barrier stopper is urged inwardly of the container by pressure exerted thereon by the fluid  284 . Fluid  284  exerts pressure on barrier member  286  as a result of pusher member  292  exerting inward pressure on plunger  294 , which pressure is, in turn, caused by the inward movement of plunger  294  as pusher housing  288  is pushed inwardly of second fill assembly housing  296 . 
     Once assembly  270  is mated with base assembly  202  in a manner shown in FIG. 54, a continued inward pressure exerted on pusher housing  288  will cause fluid  284  to flow past barrier member  286  via wall portion  280   b  and will reconstitute lyophilized drug  282 . Further pressure exerted on pusher housing  288  will cause the reconstituted drug formed by the fluid  284  which has been intermixed with drug  282  to flow through a hollow cannula,  287  past check valve  289 , into fluid passageway  312 , then through hollow cannula  278 , past check valve  78 , into passageway  208   a , then into passageway  206 , and finally into fill tube  164 . From fill tube  164  the reconstituted drug will flow into reservoir  156  causing elastomeric membrane  158  to expand outwardly in the manner indicated by the dotted lines in FIG.  54 . Prior to use, adapter portion  272  is substantially sealed by a peel cover  317  and a tear-away cap  319 . Similarly, prior to loading container assemblies  280  and  298 , both of the housings  278  and  296  as well as the fill assembly  270  are sealably closed by peel covers  321  and  323  and a tear-away cap  325  (FIG.  52 ). 
     To interconnect fill assembly  270  with base assembly  202 , adapter member  272  is mated with connector  76  of the base assembly with the bayonet locking ears  272   a  thereof being received within the circumferentially spaced slots  76   a  formed in connector  76 . Relative rotation of the fill assembly and the base assembly will effect a sterile interconnection of the fill assembly and the base assembly. As the fill assembly is aseptically mated with the base assembly, cannula  278  of the fill assembly will pierce the pierceable septum  80  which is mounted within connector  76 . This done, an inward pressure exerted either sequentially or simultaneously on pusher housing  288  and container  298  and will cause fluid to flow toward the base assembly and into reservoir  156 . 
     Referring next to FIGS. 55 through 62, yet another embodiment of the invention is there shown. This embodiment of the invention is quite similar to that shown in FIGS. 41 through 50 and like numerals are used in FIGS. 55 through 62 to identify like components. Once again, the apparatus here comprises a generally egg-shaped housing which includes a slightly different base assembly  332  (FIG. 55) as well as a slightly different cover assembly  334  (FIG.  56 ). Formed within an internal chamber  153   a  of a base component  153  of base assembly  332 , is a fluid reservoir  156  for containing the beneficial agent to be delivered to the ruminant (FIG.  58 ). Fluid reservoir  156  is formed by an elastomeric distendable member  158 , which as in the earlier described embodiments, is distended into the configuration shown in FIG. 58, by the introduction of the beneficial agent into the device via the fill means of the invention. 
     The apparatus of this latest form of the invention also includes a heat-expandable means, or mass  162 , which is carried within a chamber  153   a  and functions in the manner previously described to controllably urge fluids contained within reservoir  156  to flow outwardly into the rumen of the ruminant through the delivery means of the invention which includes a pair of diametrically opposed outlets  335  of the character shown FIG.  57 . 
     Turning particularly to FIGS. 58 and 63, a fill tube  164  extends into chamber  153   a  and cooperates with elastomeric member  158  to form reservoir  156  when the beneficial agent is introduced into the fill tube by the fill means of the invention. As in the earlier described embodiments, when the heat expandable mass  162  is heated by the body heat of the ruminant, it will expand and act upon distendable member  158  in a manner to tend to return the member toward its starting configuration and to controllably force the fluid, which is contained within the reservoir  156 , outwardly of the device, through the delivery means, and into the rumen of the animal. 
     As before, member  158  is held in position within chamber  153   a  by means of a manifold  336  having a generally cylindrically shaped neck  336   a  that extends into chamber  153   a  (FIG.  58 ). The open mouth of elastomeric member  158  is receivable over neck  336   a  and a clamping ring  170  functions to maintain the elastomeric member in sealing engagement with neck  336   a  in the manner shown in FIGS. 58 and  63 . Manifold component  336  includes a peripheral portion  337  which butts up against an edge  173   a  of a base member  173  that forms a part of base assembly  332 . When the manifold component  336  is disposed in engagement with base member  173 , in the manner shown in the drawings, both the fill tube and elastomeric member protrude into chamber  153   a  and are surrounded by heat expandable means  162 . As indicated in FIG. 58, manifold component  336  is provided with a fill passageway  338  which is in communication with the interior of fill tube  164  and is also provided is a delivery passageway  340  that is also in communication with the interior of fill tube  164 . As before, this passageway communicates with a transverse delivery passageway  341  that, in turn, communicates with outlet ports  335  (FIG.  57 ). 
     Disposed in engagement with manifold  336  is a second manifold  344  which can be interconnected with cover assembly  334  by means of a bayonet-type connector. This bayonet-type connector here comprises circumferentially spaced, generally “L” shaped brackets  346  that are affixed to the upper surface  344   a  of manifold  344  and circumferentially spaced locking ears  348  formed on the interior surface of cover assembly  334  (FIG.  56 ). Upon relative rotation between cover assembly  334  and base assembly  332 , the assemblies will be securely interconnected and maintained in sealed engagement by an elastomeric O-ring  349  (FIG.  58 ). Second manifold  344  also includes an inlet passageway  351  that is in communication with inlet passageway  338  of first manifold  336  in the manner shown in FIG.  58 . Second manifold  344  further includes first and second counterbores  354  and  356  respectively (see FIG.  58 ), which support check valve  78 , that is of the character previously described. 
     As in the earlier described embodiments, this latest embodiment of the invention is also provided with novel vent closure means  360  for opening and closing vent a passageway  362  formed in manifolds  336  and  344  respectively (FIG.  58 ). Vent passageway  362  is necessary to vent chamber  153   a  during reservoir filling at which time elastomeric member  158  expands into chamber  153   a . As best seen in FIGS. 59 through 61, this novel vent closure means comprises a unique shut off member  366  that includes a generally cylindrical body  366   a  having an elastomeric sleeve  367  and a resiliently deformable, outwardly extending spring tab  366   b . As shown in FIG. 59, sleeve  367  is closely received within a bore  368  formed in manifold  344  and is movable by locking ears  348  of cover assembly  334  from a flow open position shown in FIG. 59 to a flow closed position shown in FIG. 60 wherein body portion  366   a  blocks gas flow through vent passageway  362 . During the coupling of the cover assembly and base assembly, spring tab  366   b  is cammed downwardly by ears  348  in the manner shown in FIG.  60  and is received within a relief  369  formed in the top surface of manifold  344 . With this novel construction, once cover assembly  334  is coupled with base assembly  332 , the vent control means is inaccessible unless cover assembly  334  is removed. 
     Turning to FIGS. 63 through 69, another embodiment of the invention is there shown. This embodiment of the invention is quite similar to that shown in FIGS. 55 through 62 and like numerals are used to identify like components. Once again, the apparatus here comprises a generally egg-shaped housing which includes a slightly different base assembly  372  as well as a slightly different cover assembly  374  (FIG.  68 ). Formed within an internal chamber of  153   a  of a base component  153  of base assembly  372 , is a fluid reservoir  156  for containing the beneficial agent to be delivered to the ruminant (FIG.  63 ). Fluid reservoir  156  is formed by an elastomeric distendable member  158 , which as in the earlier described embodiments, is distended into the configuration shown in FIGS. 58 and 63, by the introduction of the beneficial agent into the device via the fill means of the invention. 
     The apparatus of this latest form of the invention also includes a heat-expandable means, or mass  162 , which is carried within a chamber  153   a  and functions in the manner previously described to controllably urge fluids contained within reservoir  156  to flow outwardly into the rumen of the ruminant through the delivery means of the invention which includes a pair of diametrically opposed outlets  376  of the character shown FIG.  64 . 
     As before, a fill tube  164  extends into chamber  153   a  and cooperates with elastomeric member  158  to form reservoir  156  when the beneficial agent is introduced into the fill tube by the fill means of the invention. As in the earlier described embodiments, when the heat expandable mass  162  is heated by the body heat of the ruminant, it will expand and act upon distendable member  158  in a manner to tend to return the member toward its starting configuration and to controllably force the fluid, which is contained within the reservoir  156 , outwardly of the device, through the delivery means, and into the rumen of the animal. 
     In this latest embodiment of the invention, member  158  is held in position within chamber  153   a  by means of fill tube  164  which fits over a generally cylindrically shaped neck  378   a  provided in manifold  378 . The open mouth of elastomeric member  158  is receivable over neck fill tube  164  in the manner shown in FIG. 63 and a clamping ring  170  functions to maintain the elastomeric member in sealing engagement with fill tube  164 . Manifold component  378  includes a peripheral portion  379  which butts up against an edge  173   a  of a base member  173  that forms a part of base assembly  372 . When the manifold component  378  is disposed in engagement with base member  173 , in the manner shown in the drawings, both the fill tube and elastomeric member protrude into chamber  153   a  and are surrounded by heat expandable means  162 . As indicated in FIG. 63, manifold component  378  is provided with a fill passageway  380  which is in communication with the interior of fill tube  164  and is also provided with a delivery passageway  382  that is also in communication with the interior of fill tube  164  (FIGS.  63  and  64 ). As before, this passageway communicates with a transverse delivery passageway  384  that, in turn, communicates with outlet ports  376  (FIG.  64 ). 
     Disposed in engagement with manifold  378  is a second manifold  386  which can be interconnected with cover assembly  374  by means of circumferentially spaced female closure clamps  389  which are affixed to the upper surface  386   a  (FIGS. 63 and 64) of manifold  386  and circumferentially spaced apart closure threads  390  formed on the interior surface of cover assembly  374  (FIG.  68 ). Upon relative rotation between cover assembly  374  and base assembly  372 , the assemblies will be securely interconnected and maintained in sealed engagement by an elastomeric O-ring  349  (FIG.  63 ). Second manifold  386  also includes an inlet passageway  392  that is in communication with inlet passageway  380  of first manifold  378  via check valve  78  in the manner shown in FIG.  63 . Second manifold  386  further includes first and second counterbores that support check valve  78 , in the manner previously described. In this latest embodiment of the invention, manifolds  378  and  386  also carry a slit septum  394  which can be used to introduce gel  162  into chamber  153   a  via passageways  395  and  396  formed in manifolds  386  and  378  respectively. An umbrella-type check valve  397  is carried by manifold  386  to control gel flow toward and away from chamber  153   a . Septum  394  is of conventional construction and is pierceable by a cannula of a conventional syringe assembly carrying gel  162 . 
     As in the earlier described embodiments, this latest embodiment of the invention is also provided with novel vent closure means for opening and closing vent passageway  400  formed in manifolds  378  and  386  respectively (FIG.  63 ). Vent passageway  400  is necessary to vent chamber  153   a  during reservoir filling at which time elastomeric member  158  expands into chamber  153   a . As best seen in FIGS. 64 through 69, this novel vent closure means comprises a unique control member  402  that includes a generally cylindrical body  404  having an elastomeric sleeve  405  and a transverse bore  404   a  therethrough (FIG.  69 ). Body  404  is rotatably received within bores  378   a  and  386   b  formed in manifolds  378  and  386  (FIG.  67 ). Control member  402  also includes a pinion-like head portion  406  having a plurality of spaced-apart teeth  406   a . Teeth  406   a  are adapted to engage a rack-like member  408  formed on the inner wall of cover  374 . As cover  374  is rotated to mate with base assembly  372 , head portion  406  will be rotated by the teeth  408   a  on rack  408  from the first position shown in FIG. 65 wherein bore  404   a  of cylindrical portion  404  is aligned with vent passageway  400  to the second position shown in FIG. 66 wherein bore  404   a  is misaligned with vent passageway  400  thereby blocking the flow of gases therethrough. With this novel construction, mating of cover assembly  374  with base assembly  372  will automatically close vent passageway  400 . Locking means, shown here as a cover locking pin  410  is insertable into a bore  412  formed in cover  374  to block counter rotation of cover  374  (FIG.  64 ). 
     Referring next to FIGS. 70 through 75, one form of the dispensing apparatus of the invention for dispensing to an animal a fluid delivery device is there shown and generally designated by the numeral  420 . This novel dispensing apparatus is usable with a fluid delivery device of the same general character as the devices heretofore described and like numerals are used to identify like components. More particularly, the fluid delivery device includes a generally egg shaped housing having a base portion within which is a disposed a heat expandable means such as gel  162  and a weight such as weight  203   a  for retaining the fluid delivery device within the rumen of the animal (FIG.  70 ). However, in this latest form of the invention, the fluid delivery device housing, which is designated in FIG. 70 by the numeral  422  includes a generally cylindrically shaped cavity  424  having a circumferentially extending recess  426  provided therein. As earlier described, the dispensing apparatus functions to position the delivery device within the throat of the animal so that the animal will swallow the device. 
     Referring to FIG. 71 wherein the dispensing apparatus is shown connected with the fluid delivery device housing  422 , the dispensing apparatus can be seen to comprise an elongated generally tubular shaped barrel  428  and a gripping mechanism  429  that is suitably interconnected with barrel  428 . Barrel  428  is of a length such that, when inserted into the throat of the animal the outboard or gripping end of the barrel is behind the tongue or even deeper in the animal&#39;s throat. When the fluid delivery device is then released in a manner presently to be described, the animal will swallow the fluid delivery device rather than coughing or spitting it out. After the delivery device is swallowed, it will reside within the animal&#39;s rumen during the prescribed delivery period. 
     Telescopically movable within barrel portion  428  is an operating member  430  having a first or forward end  430   a  and a second end  430   b . Operably associated with operating member or rod  430  is the important connector means of this form of the invention for releasably interconnecting the dispensing apparatus with the housing  422  of the delivery device. The connector means of the invention is operable by the operating rod from the first engagement position shown in FIG. 71 to the second, retracted position shown in FIG.  74 . As indicated in the drawings, the connector means of the present embodiment of the invention comprises a plurality of resiliently deformable fingers  434  each having an outwardly extending, recess-engaging element  436  (see particularly FIGS. 71,  74 , and  75 ). As shown in FIG. 71, when the operating rod  430  is in the first or forward most position, recess-engaging elements  436  extend into the recess  426  formed in cavity  424  of the fluid delivery device. Conversely, when operating rod  430  is moved by the trigger mechanism of the apparatus into its second or retracted position as shown in FIG. 74, a reduced diameter portion  428   a  of barrel  428  will cammingly engage fingers  434  moving them into the retracted position wherein they are contained interiorly of the barrel. In this retracted position, recess engaging elements  436  have traveled through circumferentially spaced openings  428   b  formed proximate the forward end of barrel  428 . With the connector means in this retracted or released position, the fluid delivery device can be readily separated from the dispensing apparatus so that it can be swallowed by the ruminant. 
     The novel gripping mechanism of the embodiment of the invention shown in FIGS. 70 through 75 comprises a hand-held grip  438  which houses a trigger mechanism  440  that is of the construction best seen in FIG.  75 . Mechanism  440  is pivotally connected to hand grip  438  for pivotal movement about a pivot pin  441  carried by grip  438  from a first position shown in FIG. 71 to a second position shown in FIG.  74 . Operating means, shown here as an outwardly extending fork-like element  443  (FIG. 75) operably interconnects trigger mechanism  440  with operating rod  430  to enable movement of said operating rod from the first engagement position shown in FIG. 71 to the second retracted or release position shown in FIG. 74 (see also FIG.  75 ). As indicated in FIG. 75, operating rod  430  is provided with a circumferentially extending groove  430   c  that receives the prongs  443   a  of element  443 . Also forming part of the gripping mechanism of the invention is biasing means for urging the trigger mechanism toward the first position shown in FIG.  71 . In this position, the operating rod is urged forwardly of barrel portion  428  and into a position wherein the connector means of the invention interconnects the dispensing apparatus with the fluid delivery means housing  422 . In the form of the invention shown in FIGS. 70 through 75, this biasing means comprising a yieldably deformable spring member  444   a  that is connected to the body portion  444  of the trigger mechanism. Body portion  444  is provided with a bore  444   b  that closely receives pivot pin  441  in the manner shown in FIG.  74 . 
     As best seen in FIG. 75, the barrel and hand grip portions of the dispensing apparatus are each constructed in two halves which are joined together to form the assembly shown in FIGS. 71 and 74. When so assembled, the operating rod is disposed interiorally of barrel portion  428  and the trigger mechanism  440  is disposed within the hand grip portion  438 . A rear cover  438   a  closes the rearward portion of the apparatus so as to encase the operating components in the manner shown in FIGS. 71 and 74. 
     In using the dispensing apparatus of the present form of the invention, with the gripping mechanism  429  gripped by the hand of the user, an inward force exerted by the fingers will cause an inward pivotal movement of trigger mechanism  440  which, in turn, will cause retraction of the operating rod into the position shown in FIG.  74 . As the trigger mechanism is squeezed against the urging of the biasing means or spring element  444   a , the trigger element will move into engagement with the trigger stop pin  445  (FIG.  74 ). With the trigger mechanism in this position, operating rod  430  has been moved rearwardly by fork-like element  443  and reduced diameter portion  428   a  of the barrel has cammed the connector means inwardly into the retracted position shown in FIG.  74 . With the apparatus in this configuration, the outboard end of the barrel can be readily inserted into the cavity  424  of the filled fluid delivery device. A relaxation of the finger pressure exerted against trigger  440  will then permit spring  444   a  to urge the trigger mechanism and rod  430  into their initial starting position shown in FIG.  71 . As the operating rod  430  moves forwardly locking elements  436  will extend through slots  428   b  formed in barrel  428  and will enter recess  426  formed in cavity  424  thereby securely locking the dispensing apparatus to the fluid delivery device (see FIG.  71 ). The fluid delivery device and the barrel portion of the dispensing apparatus can then be inserted into the animal&#39;s mouth to a position where the delivery device is rearwardly of the animal&#39;s tongue. With the delivery device in this position, a finger pressure exerted on the trigger  440  will once again cause retraction of the operating rod  430  to the second, or retracted position shown in FIG.  74 . As the operating rod  430  is retracted, the connector means will once again be moved into the configuration shown in FIG. 74 thereby releasing the fluid delivery device so that it can be swallowed by the animal. 
     Turning next to FIGS. 76 through 80, another form of the dispensing apparatus of the invention is there shown interconnected with a modified fluid delivery device. This apparatus is similar in construction and operation to that shown in FIGS. 70 through 75 and like numerals are used to identify like components. However, in this latest form of the invention, the barrel portion, which is generally designated by the numeral  446  is of a different construction and is flexible whereas barrel portion  428  of the previously described embodiment is rigid. As before, the dispensing apparatus of this latest embodiment is usable with a fluid delivery device of the same general character as the devices heretofore described, but having a generally cylindrically shaped cavity  424  provided with a circumferentially extending recess  426  (FIG.  76 ). 
     Referring particularly to FIG. 76, this latest form of the dispensing apparatus of the invention can be seen to comprise, in addition to flexible barrel  446 , a gripping mechanism  448  that is suitably interconnected with barrel  446 . Barrel  446 , like barrel  428 , is of a length such that, when inserted into the throat of the animal, the delivery device-gripping end of the barrel is located behind the tongue or even deeper in the animal&#39;s throat. 
     Telescopically movable within barrel portion  446  is an elongated operating member  450  having a first end  450   a  connected to gripping mechanism  448  and a second end  450   b  disposed within barrel  446 . Operably associated with operating member or spring  450  is the important connector means of this latest form of the invention for releasably interconnecting the dispensing apparatus with the housing  422  of the delivery device. The connector means of the invention is movable by the operating spring from the device engagement position shown in FIG. 76 to the second, retracted or released position shown in FIG.  81 . The connector means of this latest embodiment of the invention comprises a guide sleeve  452  that is telescopically movable within barrel  446 , a pusher member  454  that is telescopically movable within guide sleeve  452  and a plurality of circumferentially spaced spherical, locking members  456  that are rotatably carried within pockets  458  formed in a ball retaining housing  460  which is connected to the outboard end  446   a  of barrel  446  (FIG.  79 ). 
     As shown in FIGS. 76 and 79, when the operating spring  450  is in the first, or rearward most position, members  456  are disposed within recess  426  formed in cavity  424  of the fluid delivery device. However, when operating spring  450  is moved by the trigger mechanism into its second, or advanced position shown in FIG. 81, sleeve  452  will be moved into its forward position by a coil spring  462  which is acted upon by a pusher block  464  to which spring  450  is connected as by soldering. As sleeve  452  moves forwardly within ball retaining housing  460  recess  452   a  formed in sleeve  452  will move into index with spherical members  456  causing them to move out of recess  426  and into recess  452   a . As spherical members  456  clear recess  426 , the fluid delivery device will, in the manner shown in FIG. 81 separate from the dispensing apparatus due to the urging of the forward extremity or sleeve  452  and pusher block  464  thereby freeing the delivery device so that it can be swallowed by the ruminant. 
     As best seen in FIG. 79, pusher block  464  moves within a flexible helix  466  which is carried within a flexible metal braid tube  468  that is, in turn, disposed with an elongated high polymer tube  470 . With this construction, helix  466 , metal braid tube  468  and high polymer tube  470  cooperate with an outer polymer tube  472  to make up flexible barrel  446 . The flexibility of barrel  446  assists in administering the fluid delivery device to the ruminant and helps to prevent injury to the animal during the dispensing step. 
     The gripping mechanism of the embodiment of the invention shown in FIGS. 76 through 81 is somewhat similar to that previously described and comprises a hand-held grip  448  which houses a slightly differently configured trigger mechanism  469 . Trigger mechanism  469  is pivotally connected to hand grip  448  for a pivotal movement about a pivot pin  473  from a first position shown in FIG. 76 to a second position shown in FIG.  81 . Drive spring  450 , which comprises the operating means of this latest embodiment of the invention, operably interconnects trigger mechanism  469  with pusher block  464  and with pusher member  454  to enable movement of these components from the first device engagement position shown in FIG. 76 to the second advanced or release position shown in FIG.  81 . 
     As indicated in FIGS. 76 and 80, hand grip  448  is interconnected with barrel  446  by means of a coupler component  475 , the forward portion of which is received within metal braid tube  468 . As before, biasing means, shown here as a coil spring  477 , urges the trigger mechanism toward the starting position shown in FIG.  76 . Spring  477  is housed with grip  448  with one end thereof in engagement with a guide wall  480  and the other end in engagement with a washer  482  which is affixed to drive spring  450  (see also FIG.  80 ). Guide wall  480  has a central bore  480   a  that assists in guiding the reciprocal movement of drive spring  450  within barrel  446 . Body portion  484  of trigger  469  is provided with a bore  484   a  that closely received pivot pin  473  in the manner shown in FIG.  71 . 
     As indicated in FIG. 80, the hand grip portion of the dispensing apparatus is constructed in two halves which can be joined together to form the grip assembly shown in FIGS. 76 and 77. When the grip assembly is interconnected with coupler component  475  in the manner shown in FIG. 76, end  450   a  of the operating spring will be anchored interiorally of the hand grip and the operating spring will be entrained through the hand grip, through opening  480   a  in wall  480  and then longitudinally of barrel portion  446 . 
     In using the sensing apparatus of this latest form of the invention, with the hand grip portion  448  gripped by the hand of the user, an inward force exerted by the fingers will cause inward pivotal movement of trigger mechanism  469  which, in turn, will cause forward movement of the operating spring into the position shown in FIG.  81 . As the trigger mechanism is squeezed against the urging of the biasing means or spring  477 , a drive spring swing arm  486 , which is affixed to drive spring  450 , will pivot about a pivot pin  487  and into engagement with a stop pin  488  (FIG. 81) thereby stopping forward movement of the drive spring. With the trigger in the position shown in FIG. 81, the operating spring has advanced sleeve  452  to a location wherein spherical members  456  will drop into recess  452   a . At the same time, pusher member  454  will advance into pushing engagement with the fluid delivery device causing it to separate from the dispensing apparatus. A relaxation of the finger pressure exerted on trigger  469  will permit springs  462  and  477  to urge the operating components into their original starting position. To connect the dispensing apparatus with another delivery device, the trigger needs to be depressed so as to permit the outboard end ball retainer  460  to be inserted into the cavity  424  formed in the fluid dispensing device. Release of finger pressure will then cause spherical members  456  to move into locking engagement within recess  426  in the manner shown in FIGS. 76 and 79. 
     Having now described the invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difficulty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth in the following claims.