bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rectal Absorption in the Desert Locust, Schistocerca Gregaria Forskål
Authors: Phillips J. E. 
Published: April 2021

ABSTRACT
The absorption of Na, K and Cl from the rectum has been studied in locusts previously supplied either with tap water or with hypertonic saline, the latter treatment resulting in a 40 –70 % increase in the ionic concentrations in the haemolymph. Both water-fed and saline-fed locusts can absorb Na, K and Cl from the lumen of the rectum against concentration differences of up to 100-fold. The lumen is 15-30 mV. positive to the haemolymph. Absorption of Cl is certainly an active process; absorption of Na and K probably involves active processes. In water-fed locusts absorption of K is four to twelve times more rapid than that of Na, and absorption of Cl is three times faster from KC1 than from NaCl. In saline-fed locusts the relative rates of absorption of Na, K and Cl are the same as in water-fed locusts, except when the concentrations in the rectal fluid exceed those in the haemolymph. The experimental results are consistent with the hypothesis that regulation of absorption of water and of ions from the rectum is brought about by changes in the passive permeability of the epithelium rather than by changes in mechanisms of active transport.
Biology and Physics of Locust Flight
Authors: Weis-Fogh Torkel 
Published: April 2021

ABSTRACT
A calorimetric method was designed which makes it possible to estimate the metabolic rate of a flying insect with an accuracy of ±10%. For the first time, the metabolic rate of a flying animal has been related to the main aerodynamic component of force, the lift. The metabolic rate of locusts increases almost linearly from 41 kcal, kg.-1 hr.-1 at 50% relative lift to no kcal, kg.-1 hr.-1 at 170%. The results are in accordance with theoretical deductions and they show that the work necessary to accelerate the oscillating wings (inertia terms) is small compared with the aerodynamic work—probably three to five times smaller. In flapping insects and small birds the metabolic rate per unit weight seems to be independent of size. The control of power is discussed.
Gill Ventilation Volumes, Oxygen Consumption and Respiratory Rhythms in Carcinus Maenas (L.)
Authors: Arudpragasam K. D. , Naylor E. 
Published: April 2021

ABSTRACT
An apparatus is described for continuously measuring gill ventilation volumes in crabs. Large Carcinus pump about 1 c.c./g./min. and consume oxygen at the rate of about 0·03 c.c./g./hr. whilst smaller specimens pump up to 1·5 c.c./g./min. and consume up to 0·1 c.c./g./hr. Freshly collected crabs show persistent tidal and 24 hr. rhythms of pumping activity and oxygen consumption. In response to oxygen depletion Carcinus shows increased rates of gill ventilation and increased percentage utilization. Prolonged exposure to increased carbon dioxide results in a short-lived inhibition followed by over-compensation and then progressive inhibition of respiratory activity. The results are discussed in relation to previous work on respiration in other decapod Crustacea.
The Waterproofing Mechanism of Arthropods
Authors: Beament J. W. L. , Noble-Nesbitt J. , Watson J. A. L. 
Published: April 2021

ABSTRACT
The firebrat, Thermobia, is very impermeable to the outward flow of water, losing only 0·013 mg. of water/mm. Hg saturation deficit/hr./standard animal of 30 mg. between 19 and 26° C. The permeability increases to a higher level at a critical temperature just below 30° C. and well below the optimal temperature for the insect as a whole. The waterproofing is mobile, for it regains its lower permeability on cooling below the transition temperature and is also restored a short time after abrasion. Extractions support the hypothesis that the impermeable layer is a stiff, epicuticular grease but further suggest that an imperforate lamella, perhaps a cement, lies over the grease. The live firebrat can absorb water from moist air, reaching an equilibrium between absorption and transpiration at a saturation deficit of approximately 10 mm. Hg at a temperature of 21° C. Although abrasion of the integument decreases the net rate of water uptake and lowers the saturation deficit at which equilibrium is possible, it may act only by increasing temporarily the rate of transpiration.
Visco-Elastic Properties of the Mesogloea of Jellyfish
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
The mesogloea of Scyphozoa (Cyanea and Chrysaora) differs from that of Anthozoa in having higher elastic compliance, in having a broad distribution of retardation times, and in that creep recovery is very slow. In the second of these properties the scyphozoan mesogloea resembles simple polymeric gels.
Activation of the Sodium Uptake System at High Blood Concentrations in the Amphipod Gammarus Duebeni
Authors: Lockwood A. P. M. 
Published: April 2021

ABSTRACT
Some factors responsible for eliciting an increase in the rate of active uptake of sodium by Gammarus duebeni have been studied. Animals previously acclimatized to high salinities (100-161% sea water) had their blood concentration suddenly lowered by treatment with deionized water to a level similar to, but a little above, that of animals kept in 50-66% sea water. Both groups were placed in the same tracer medium, i.e. 5% sea water labelled with 22Na and with sucrose added. The animals treated with deionized water showed an influx, on average, of 4 times that of the controls from 50 to 66% sea water. No increase in influx followed treatment of animals from 161% sea water with 50% sea water or with sucrose solution isosmotic with 50% sea water, despite the fact that the osmotic gradient between 161 and 50% sea water is greater than the gradient between 100% sea water and deionized water. It is concluded that in these experiments the rate of uptake is not influenced primarily by the absolute concentration of the blood, the rate of change of blood concentration, the rate of swelling of the tissues or the extent of the blood volume. The possibility is considered that both the concentration of the urine and the rate of uptake of sodium may, in some circumstances, be controlled by an exteroreceptor which monitors the concentration of the medium and mediates its effect via a humoral system.
Excretion in the Blood-Sucking Bug, Rhodnius Prolixus Stål
Authors: Maddrell S. H. P. 
Published: April 2021

ABSTRACT
The diuresis of freshly fed larvae of Rhodnius is controlled by afferent nervous information from the abdomen. This information is supplied by abdominal stretch receptors sensitive to vertical distension of the abdomen. It is most probable that the receptors are in the vertical tergosternal muscles, a trio of which occurs towards each lateral edge in abdominal segments 2−7 inclusive. It is suggested that diuresis in Rhodnius is a reflex response to the distension of the abdomen brought about by the swelling of the anterior part of the mid-gut during feeding.
Experiments On Substrate Selection by Corophium Species: Films and Bacteria On Sand Particles
Authors: Meadows P. S. 
Published: April 2021

ABSTRACT
A simple method is described for determining the substrate preferences of Corophium volutator (Pallas) and Corophium arenarium Crawford. If offered a choice of its own substrate with that of the other species each prefers its own. Level of illumination and colour of substrate have little effect on choice. An animal’s size and hence its age has little effect on its substrate preferences. C. volutator prefers a substrate previously maintained under anaerobic conditions, C. arenarium vice versa. Treatments which kill, inactivate, or remove micro-organisms render sands unattractive to Corophium. These include boiling, acid-cleaning, drying, and soaking in fixatives or distilled water. Attempts to make these sands attractive again failed. Distilled water, and solutions of the non-electrolytes sucrose and glycerol at the same osmotic pressure as sea water, induce many bacteria to desorb from sand particles ; smaller numbers are desorbed in the presence of solutions of electrolytes at the same ionic strength as sea water (NaCl, Na2SO4, KC1, MgSO4, MgCl2, CaCl2). Of all these, only distilled water and solutions of MgCl2 and CaCl2 reduce the attractive properties of sands. Hence the loss of bacteria from the surface of sand grains, though related to the ionic strength and composition of the medium, is not necessarily associated with a substrate becoming unattractive.
Studies On Crop Function in the Cockroach (Periplaneta Americana L.)
Authors: Davey K. G. , Treherne J. E. 
Published: April 2021

ABSTRACT
The initial hydrostatic pressure developed in the crop on feeding was independent of the osmotic concentration of the ingested glucose solution. It is calculated that the pressure increase was not the result of a simple compression of the air contained in the crop, but that the feeding process must have involved a significant release of air from this structure. The pressure pulses which developed after feeding appeared to be dependent on the same nervous pathway as that determining the frequency of opening of the proventricular valve. They also decayed at the same rate as the frequency of opening of the valve. Such a linkage between the pressure pulses and the opening of the valve might ensure a maximum pressure gradient between the lumen of the crop and the midgut. An appreciable negative hydrostatic pressure was demonstrated in the haemolymph, which, if transmitted to the lumen of the midgut, would facilitate the maintenance of the hydrostatic pressure gradient across the proventricular valve. Both the general and transient pressures within the crop decayed exponentially, there being no significant difference when solutions of different osmotic pressure were used. With a viscous solution (containing 4% methyl cellulose) the pressure changes were of the same order as with normal solutions, except that the transient pressure pulses tended to remain constant after an initial relatively rapid fall. A quantitative analysis, based on a modified Poiseuille relation, showed that the effective dimensions of the proventricular valve increased with time, the initial value of the ‘valve parameter ‘being smaller and the rate of increase more rapid with the more concentrated solution. It is concluded that variations in the effective dimensions of the valve contribute to the demonstrated control of crop-emptying at different osmotic concentrations. The possible nervous mechanism capable of controlling the release of fluid from the crop is considered.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D. 
Published: April 2021

ABSTRACT
Electrical threshold curves have been obtained for the stimulation by square and saw-tooth pulses of peripheral melanophore-aggregating nerve fibres in the minnow, Phoxinus. The responses show complete independence of pulse repetition rate over a wide range. The results of von Gelei on the electrical stimulation of the spinal cord in ergotamine-treated minnows have been confirmed but it is found that the melanophore-dispersing activity may pass forwards or backwards from a stimulating electrode at any level of the spinal cord. Identical results have been obtained for melanophore-aggregating activity in non-ergotized fish. All the spinal responses are slow and incomplete at repetition rates below 10/sec. Von Gelei’s arguments for mapping the pathways of melanophore-dispersing nerve fibres are shown to be insupportable.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D. 
Published: April 2021

ABSTRACT
Responses of melanophores to injections of adrenalin or L-noradrenalin have been examined with and without prior injection of ergotamine. Responses of the melanophores of isolated skin preparations in solutions containing adrenalin or L-noradrenalin have been examined with and without prior injections of, or direct exposure to, solutions of ergotamine. No reversal of response could be found in any of the above cases. Responses of melanophores following injections of Rogetine (an alternative adrenergic blocking agent) are quite unlike those after ergot but closely resemble those after atropine. It is concluded that it is unjustified to assume that drugs produce similar effects in fishes and in mammals. The case for double innervation of melanophores is therefore still unproven.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D. 
Published: April 2021

ABSTRACT
The rate of chromatic adaptation to background colour has been examined briefly in thirty-three species of teleost fishes (from nineteen families, eight orders) to test the presence of nervous control of chromatophores. The same fishes have then been tested for chromatic responses to local heating or cooling of the skin. Thermal responses resembling those of Phoxinus have been found in fourteen species which show quick adaptation, but not in thirteen other such species. No thermal responses have been found in any of the six species which do not show quick adaptation. There appears to be no significance in the taxonomic distribution of these results and no new responses to temperature have been found.
Electrophysiological Investigations of the Heart of Squilla Mantis
Authors: Brown Hilary F. 
Published: April 2021

ABSTRACT
With an external hook electrode placed upon the ganglionic nerve trunk of the isolated heart of Squilla mantis a burst of a small number (3-12) of nerve impulses was recorded at each heart beat. The number of impulses per burst showed a direct correlation with interval between bursts. The only consistent feature of impulse pattern within the bursts was a lengthening of the intervals between impulses towards the ends of the bursts. Electrodes at two points on the ganglionic nerve trunk each recorded the same number of impulses at a burst. The delay between the two recording points was the same for all impulses, and usually all the impulses were, in a given heart, recorded travelling in the same direction, though this could be either forwards or backwards along the chain. It is suggested that each cell in the chain of 16 fires in succession the same number of times during a burst and that the impulses travel along the same ‘firing channel’ within the ganglionic nerve trunk. Cells near the two ends of the chain showed the greatest spontaneity when isolated by transverse cuts or ligatures. Coupled with the records obtained from two points, this suggests that the bursts are initiated in the front or back regions of the chain, but not invariably by the same one of the 16 cells.
Electrophysiological Investigations of the Heart of Squilla Mantis
Authors: Brown Hilary F. 
Published: April 2021

ABSTRACT
The histology of the heart muscle of Squilla mantis is briefly described. Vital staining with methylene blue revealed only a sparse distribution of nerve endings on the muscle network. Intracellular electrodes recorded from the muscle a multi-peaked junction potential at each heart beat. Each peak followed an impulse in the ganglionic nerve trunk burst. All the peaks were approximately the same height and none more than about three-fifths the height of the resting potential (average values for 10 hearts: resting potential, 51·5 mV; junction potential, 27·6 mV). Inverted (negative-going) signals were never recorded just outside the muscle membrane suggesting that at all the points which were searched the membrane was acting passively. Driving Squilla heart muscle via its nerve supply at too stimuli per second did not depolarize it by more than about 35 mV, nor would depolarizing pulses given directly to a fibre through an intracellular electrode set up any sort of current-generating activity in the membrane. The magnitude of muscle contraction, measured locally using a microelectrode transducer, depended on the absolute level of the potential across the membrane, rather than on change of potential. A directly applied electrotonus, similar in magnitude and duration to the nerve-induced junction potential, caused a local contraction of similar magnitude. The recorded junction potential is therefore interpreted as the composite record of the electrotonus spreading within the muscle network from current initiated at relatively infrequent active points on the muscle membrane (the nerve endings) which passively depolarizes the rest of the membrane. The junction potentials showed facilitation when the intervals between them were below 4 sec. At intervals less than 630 msec, they summed.
The Swimming Response of the Sea Anemone Stomphia Coccinea to Electrical Stimulation
Authors: Ross D. M. , Sutton L. 
Published: April 2021

ABSTRACT
The swimming response of Stomphia coccinea evoked by electrical stimuli has been re-examined. Contrary to earlier accounts, definite relationships have been discovered between the occurrence of swimming and the number, frequency and intensity of electrical stimuli applied. At higher frequencies (1 stimulus/0·4 sec.), 4·6 stimuli cause swimming; at lower frequencies (1 stimulus/3·0 sec.), 24−40 stimuli are needed to produce the same effect. Stronger stimuli are required to evoke the swimming response than to cause the retraction response. At constant durations, the threshold for swimming is at least 50% above the voltage required for retraction; at constant voltage, the threshold duration of pulses that give swimming is at least three times the duration of pulses that cause retraction. It is concluded that retraction and swimming are controlled by different excitation systems. The system controlling swimming has a higher threshold and it is not an all-or-nothing process. The results are discussed in relation to facilitation of the swimming response and some behaviour patterns in another sea anemone, Calliactis parasitica.
Inhibition of the Swimming Response by Food and of Nematocyst Discharge During Swimming in the Sea Anemone Stomphia Coccinea
Authors: Ross D. M. , Sutton L. 
Published: April 2021

ABSTRACT
The discharge of tentacular nematocysts in response to food was studied in Stomphia coccinea before and during swimming, and during the period of resettling. The tendency of Stomphia’?, nematocysts to discharge on contact with food virtually disappeared during the swimming response. The disappearance of the nematocyst response coincided with the release of the pedal disk; its reappearance coincided with the re-attachment of the pedal disk. Objects rubbed on the aboral surface of Dermasterias can cause swimming if brought into contact with a single tentacle of Stomphia. A general inhibition of the swimming response to objects rubbed on Dermasterias was set up by flooding the tentacular crown with a food extract. A local inhibition was set up when food was applied to a single tentacle just before the same tentacle was touched with material from Dermasterias. The results are discussed in relation to the view that nematocysts function as independent effectors.
Blood Volumes, Blood Distribution and Sea-Water Spaces in Relation to Expansion and Retraction of the Foot inBullia(Gastropoda)
Authors: Brown A. C. 
Published: April 2021

ABSTRACTThe expansion and retraction of the foot has been studied in the prosobranchiate sandy-beach gastropod, Bullia. In Bullia the foot is capable of an unusually great expansion, but this is not dependent upon an unusually large volume of blood. Radiographical investigations have shown that on retraction blood flows direct from the pedal sinus to the visceral sinus system without passing through the heart, kidney or gill. Investigation of the jets of water produced on retraction has shown that in the expanded animal the visceral region within the shell is surrounded by sea water. The roles of blood movement and of contraction of the columella muscle, and also various other aspects of the circulation, are discussed.
Black and White Preferences in the Frog, Rana Temporaria, and Other Anura
Authors: Boycott B. B. , Mrosovsky N. , Muntz W. R. A. 
Published: April 2021

ABSTRACT
Conditions are described in which the frog, Rana temporaria, selects the darker of two stimuli. Some similar observations are reported for other amphibians. Further experiments suggested that a dark starting area is a factor tending to decrease negative phototaxis. Forcing the frogs from the dark starting area decreased the scores for the darker of two stimuli. No strong positive phototaxis was found in the present experiments. In conditions giving negative phototaxis there is a slight preference for blue over green. These results are compared to previous work and discussed in relation to the possible underlying mechanism and their biological value.
Some Preliminary Observations on the Effects of Cations on Conduction Processes in the Abdominal Nerve Cord of The Stick Insect, Carausius Morosus
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
In the haemolymph of the stick insect Carausius morosus the concentration of potassium exceeds that of sodium and the concentration of magnesium exceeds that of calcium. The implications of this situation for nerve conduction have been studied. Conduction is maintained in intact and desheathed preparations of the fourth adbominal ganglion under irrigation with a solution resembling haemolymph in ionic composition. Action potentials recorded in response to electrical stimulation of the nerve cord decline in sodium-free solutions, both in intact and in desheathed preparations. Conduction declines slowly under irrigation with magnesium-free solutions both in intact and in desheathed preparations.
The Motion of Strigomonas Oncopelti
Authors: Holwill M. E. J. 
Published: April 2021

ABSTRACT
The movement of the flagellum of Strigomonas oncopelti has been studied using high-speed cinephotography. Waves usually pass along the flagellum from tip to base but under certain conditions waves are propagated from base to tip, reversing the direction of movement of the organism. Increasing the viscosity of the medium reduces the frequency of beat while the shape of the wave remains unaltered. The variations in the wave parameters with increasing viscosity are consistent with a mechanically propagated wave. Calculated values for Young’s modulus indicate that the membrane, the matrix, the nine peripheral fibrils or the central pair could act as the compressive elements needed to resist bending. The mechanism controlling the direction of wave propagation appears to lie in the membrane.
Three Parallel Conducting Systems in the Stalk of A Hydroid
Authors: Josephson Robert K. 
Published: April 2021

ABSTRACT
There are three, non-polarized conducting systems in the stalk of Tubularia. These are termed the distal opener system (DOS), the triggering system (TS), and the slow system (SS). The DOS controls opening of the distal tentacles of the hydranth. Activation of the DOS produces a small electric pulse in the stalk which is conducted at about 15 cm./sec. At the base of the distal tentacles this pulse is followed by a slow potential. The slow potential but not the pulse shows antifacilitation and is quickly blocked by excess Mg2+, as are distal tentacle movements. This is taken to indicate that the pulse and slow potential are a result of nerve and muscle activity respectively. The TS can trigger the potentials which normally appear spontaneously in the neck region of the hydranth. The TS conducts at about 17 cm./sec and has a lower threshold than the DOS. No electrical correlate of TS activity has been found. Activation of the SS produces large (up to 1 mV.), slowly propagated (about 6 cm./sec.) potentials in the stalk. The SS is very labile. In a fresh animal the SS threshold is two to three times that of the DOS and the SS often fires repetitively to stimuli above its threshold. SS activity has apparently no effect on polyp behaviour or on spontaneous electrical activity in the hydranth.