bluuebunny/crossref_metadata_2025 huggingface dataset:
The Onset of the Fast Phase in the Optokinetic Response of the Crab, Carcinus
Authors: Horridge G. A. , Burrows M.
Published: April 2021

The onset of the fast phase in the optokinetic response is a part of a centrally determined programme. An eyecup moving in a slow phase toward the mid line governs the onset of the fast phase for both eyes and leads by 40−60 msec. Repeated reflex withdrawal of a governing eyecup suppresses the onset of the fast phase; similar stimulation of a governed eyecup has no effect on fast phases. After shocks applied near the governing eye the onset of the fast phase occurs earlier in the slow phase. Mechanical stimulation has the same effect. If the eyecup receives a shock whenever it moves too near the mid line in a slow forward phase, it soon changes the position of onset of the fast phase so that the shocks are avoided. The tonic motor frequency to muscle 21 at which the fast phase normally occurs is reduced. The effect is lasting. This plastic change is adaptive but is not learning; the earlier onset occurs irrespective of how or when the shocks are applied. The reinforcement need not supply any possibility of association. In a behaviour pattern which depends on a centrally determined programme of motor impulses for each stimulus situation the element of plasticity is one further component of the central pattern, so arranged that it is adaptive.
Development of A Computer Model Simulating Some Aspects of the Cardiovascular-Respiratory Dynamics of the Salmonid Fish
Authors: Taylor W. , Houston A. H. , Horgan J. D.
Published: April 2021

A digital computer simulation depicting some features of cardiovascular-respiratory interaction in the salmonid fish has been developed. This embodies six controlled system relationships; three of which are mass balance equation describing oxygen transport and storage in the extra-branchial, branchial and general body phases. A Fick equation, and two relationships approximating the transport characteristics of venous and arterial blood are also included in the system equations. Three feedback equations provide for adjustments in cardiac output, ventilation and exchange surface area. The model predicts, with reasonable accuracy, values for ventilation, cardiac output and blood gas tensions under conditions of routine and moderate activity in an oxygen-sufficient environment. Qualitative agreement between predicted and experimental values has been obtained in simulations of responses to progressive environmental hypoxia. The study emphasizes the probable role of venous oxygen tension in the regulation of ventilatory and cardiac activity. A central role for branchiovascular responses in adaptation to elevated oxygen demand is also indicated. The existence of a depressor function, operating under conditions of acute hypoxia to dampen positive ventilatory feedback effects is suggested by simulation of responses to reduced environmental oxygen tensions.
Motor Performances of Some Cephalopods
Authors: Trueman E. R. , Packard A.
Published: April 2021

It has long been recognized that contraction of the mantle muscles of a pelagic cephalopod produces high hydrostatic pressure in the mantle cavity, a jet of water from the funnel and movement of the animal in the opposite direction (Fig. 1). As a result of their investigation of the responses of squid muscle to repetitive stimulation of giant nerve fibres, Prosser & Young (1937) considered that the expulsion of each jet of water, occurring in locomotion, is a single unitary act which is performed in an all-or-nothing manner. Absence of any increased response in fresh muscle preparations at higher frequencies showed that a single nerve impulse carried by a giant axon is capable of activating every muscle fibre that it reaches. In parallel with the decapod fast system there is a slow system made up of many small-diameter nerve fibres, which when stimulated provoke smaller graded muscular contractions in a mantle preparation (Young, 1938). This author assumed that these graded contractions produced the mantle movements involved in respiration. The graded contractions were further studied by Wilson (1960) who demonstrated that Octopus (O. bimaculatus and 0. bimaculoides) also have a fast and a slow system. The fast system of Octopus, unlike that of the decapods, shows marked facilitation of the mechanical response and a single: twitch takes 160 m.sec. to reach maximum tension. Summation of Octopus fast and slow systems and of the squid slow response take place in a two-phase manner, a rapid increase in tension being followed by a slower rise.
On Respiration in the Dragonet Callionymus Lyra L
Authors: Hughes G. M. , Umezawa Shun-Ichi
Published: April 2021

The usefulness of a bottom-living fish, the dragonet (Callionymus lyra), in experiments on fish respiration is described. The position and nature of its opercular opening made it possible to determine directly the volume of water pumped over the gills and the of the mixed expired water. The normal ventilation volume for a 100 g. fish was about 30 c.c./min. The relationship between cardiac and respiratory rhythms was investigated and showed a variety of ratios. The heart usually beats more than once during each respiratory cycle. Individual variations in the coupling between these rhythms was common and close couplings were observed in the absence of anaesthetic and at normal . Changes in minute volume produced by altering the hydrostatic pressure across the respiratory system did not affect the heart rate. Percentage utilization fell at higher flow rates. Changes in flow per cm. of water pressure gradient was less with negative gradients than when the static pressure on the mouth side exceeded that in the opercular collecting chamber. Oxygen consumption of the fish is directly related to the ambient over a wide range (30-120 mm. Hg). Sudden lowering of the in the inspired water leads to compensatory responses in which the minute volume is maintained or increased as a result of a rise in stroke volume and lowered respiratory frequency: there is also a marked bradycardia. During recovery the increased oxygen consumption of the fish resulted from a rise in utilization rather than a change in the respiratory rate or ventilation volume. Analysis of the time course of the changes in heart rate and ventilation volume in experiments in which was changed supports the view that the receptors mediating bradycardia occur on the gills and respond directly to the change in rather than to the secondary increase in flow produced by the hypoxia.
The Kinematics and Dynamics of Ciliary Fluid Systems
Authors: Miller C. E.
Published: April 2021

The difficulties of directly applying the methods of Newtonian mechanics to solve the problem of mucus flow in the mammalian trachea are discussed. In order to circumvent these difficulties, a sophisticated model of the mucociliary system, called the circular rheociliometer, was constructed. A brief account is given of the model and the homomorphic relation it has to the mucociliary system of mammal. Kinematic experiments are described in which observations on the model are compared with observations on the mucociliary system of the cat’s trachea. A coefficient of energy, which is the ratio of energy loss in the fluid to the kinetic energy supplied by the cilia, is developed. The coefficient of energy is plotted against the Reynolds number for the model and for the cat’s trachea. It is shown that both sets of data fall within the same range of Reynolds numbers. Based on other kinematic and dynamic similarities, which are shown to exist between the two systems, a hypothetical mechanical exemplar of the mucociliary system is derived.
A Comparative Study of Central Blood Pressures in Five Amphibians
Authors: Shelton G. , Jones D. R.
Published: April 2021

The temporal relationships of blood pressures recorded from the ventricle, conus and arterial arches are identical in Rana, Bufo and Xenopus. Pressure levels in the arterial arches are very similar in all the species. The pulse in the ventricle is large and the pressure falls to zero during diastole. Continued conus contraction after ventricular relaxation causes a divergence of pres-sure in the two chambers. Divergence between conus and arterial pressures follows as the conus relaxes. Pressure gradients between the various recording sites during forward movement of the blood is small. Theoretical considerations show that pressure-flow relationships approximate to the formula of Poiseuille. They also pro-duce no evidence for substantial pressure gradients during blood ejection. Blood pressures recorded in Salamandra are significantly lower than in the anurans. The systemic and pulmocutaneous pulses are identical, unlike the condition in anura where the pulmocutaneous pulse is almost invariably the larger. In all other respects the pressure relationships in Salamandra are identical to those in anurans.
The Sensitivity of Housefly Photoreceptors in the Mid-Ultraviolet and the Limits of the Visible Spectrum
Authors: Goldsmith Timothy H. , Fernandez Hector R.
Published: April 2021

In experiments published in his book of 1882, Sir John Lubbock demonstrated that removal of the ultraviolet (u.v.) wavelengths decreased the effectiveness of natural sunlight in stimulating ants to carry their pupae into the dark. An apparently high sensitivity to near-ultraviolet light was subsequently shown in studies of phototaxis in bees (Bertholf, 1931a, b; Heintz, 1959) and flies (Bertholf, 1932; Cameron, 1938). More recently electrophysiological techniques have been employed to study selective adaptation of the retinal action potential (Walther & Dodt, 1959; Goldsmith, 1960) and the spectral responses of single retinular cells (Autrum & Burkhardt, 1960; Autrum & von Zwehl, 1962, 1964; Burkhardt, 1962; Autrum, 1965). This work demonstrates that honeybees (Apis) have u.v. receptors with peak sensitivity at 340 nm. and the cockroach (Periplaneta) at ∼ 350 nm. The photoreceptors of flies (Calliphora) show two maxima, one of which lies at about 350 nm. The peaks are less well defined, but u.v. receptors maximal at about 350 nm. also seem to be present in Coleoptera, Lepidoptera (Hasselmann, 1962) and probably Odonata (Ruck, 1965). These peaks are not due to secondary excitation of the visual pigments through fluorescence of accessory pigment for (1) both bees and flies are phototactically several times more sensitive to the 365 nm. mercury line than to any longer wavelengths (Bertholf, 1931a, b, 1932; Cameron, 1938); (2) in flies the u.v. maxima seen in the retinal action potential are higher than the peaks in the visible region of the spectrum (Walther & Dodt, 1959; Burkhardt, 1962); and (3) bees can be trained to discriminate u.v. from all other wavelengths or mixtures of wavelengths (e.g. Daumer, 1956).
Effect of Season and Sex on the Photopic Spectral Sensitivity of the Three-Spined Stickleback
Authors: Cronly-Dillon John , Sharma Sansar C.
Published: April 2021

It is now almost two decades since Tinbergen and his associates (Tinbergen, 1951 ; Tinbergen & van Iersel, 1947; van Iersel, 1953) identified the relevant features of visual displays which trigger sexual and parental behaviour in the three-spined stickleback. Specifically, they showed that during the breeding season, when the female’s abdomen is swollen with eggs, the latter serves as a visual sign stimulus which triggers appropriate sexual behaviour in the sensitized male. In addition, the red colouring which the belly of the male acquires during this period was found to elicit, in other sensitized males, the complex behaviour patterns which characterize the defence of territory in this species.
The Effects of Pituitrin and of Narcosis on Water-Regulation in Larval and Meta-Morphosed Amblystoma
Authors: Bělehradek J. , Huxley J. S.
Published: April 2021

Injection of post-pituitary extract to larval and adult Amblystoma individuals leads to an increased water-intake, followed by a decrease in water-content of the body, the decrease being greater than the preliminary increase. Repeated injections cause decreases of body-weight of over 35 per cent. This effect runs parallel with the chromatophore effect. No change in oxygen consumption could be detected, even with long continued injection. Both larval and metamorphosed Amblystoma lose weight (by loss of water) when narcotised in a solution of amytal 1 : 3000 ; the loss is greater in larval specimens; the decrease is followed, in metamorphosed animals, by a slight net increase. Both the pituitary effect and the amytal effect develop considerably more quickly in larval than in metamorphosed Amblystoma. The mechanism regulating the water-equilibrium of the body in Amblystoma passes, during metamorphosis, from a relatively imperfect state in the larval stage to a more efficient condition in adult individuals.
A Study of Arginase Content in the Fowl With Special Reference to Sex
Authors: Chaudhuri A. C.
Published: April 2021

The enzyme arginase which occurs in various organs of different animals was first discovered by Kossel and Dakin (1904) in the mammalian liver. Clementi (1916, 1918, 1922) found arginase in the liver of mammals, amphibians and fishes and the turtle, but he did not find any in the liver of birds and of the majority of reptiles. He found the enzyme to be present in the kidney of birds. Hunter and Dauphinee (1924) found a considerable amount of arginase in the liver of mammals and fishes. They also established the presence of arginase in the kidney of mammals and fishes, but usually in an amount smaller than that present in the liver. In the organs of fishes other than the liver, heart and kidney, the distribution of arginase appeared to be variable. In mammals these workers did not find arginase in any organs except the liver and the kidney, while in birds they could find it only in the kidney.
The Effect of the Injection of Alcohol Into the Male Mouse Upon the Secondary Sex Ratio Among the Offspring
Authors: Chaudhuri A. C.
Published: April 2021

Bluhm (1921) found that in the mouse the injection of alcohol into the male parent was followed by a remarkable rise in the sex ratio among the offspring. The results of Danforth (1926), who administered alcohol in the form of vapour, confirmed this finding, as did those of Parkes and Bellerby (1926). MacDowell and Lord (1926) and Crew (1926) found that severe exposure of the male to alcohol fumes was not followed by any disturbance of the secondary sex ratio. In view of this disparity, it was suggested to me by Dr Crew that the difference in results might possibly be but a reflection of the difference in the method of exhibiting the alcohol and that it would be a profitable study actually to repeat Bluhm’s work, using her technique.
Studies on Calcium Metabolism
Authors: McIsaac P.
Published: April 2021

It was thought to be of interest to determine the relation that exists between the serum-calcium content of mother and offspring in the rabbit. Comparatively little work has been done on the calcium content of maternal and foetal blood and that which has been done is more or less recent and is concerned with cattle and man. Robinson and Huffman (1926) found that the blood of the cow at calving had a lower calcium content than that of the calf, and that the tendency in the case of the calf was for the calcium to decrease during the first week of the calf’s life. In the case of the mother there is a drop in calcium at the end of pregnancy, but after calving there is an immediate rise, which continues for several days. Hellmuth (1925), working on man, found that the calcium content was always 20–30 per cent, higher in the foetal than in the maternal blood. H. A. and H. I. Mattil (1922), also working on human blood, found on the other hand that at birth the infant’s and mother’s blood were identical in calcium content, and during several months after birth the calcium in the infant’s blood increased, reaching a variable maximum, often double that at birth. Thereafter there was a gradual decrease. Harding (1925) in his review of metabolism in pregnancy states that Ca, P, Na and K appear to be higher in foetal than in maternal blood.
On The Occurrence of Haemoglobin and of Erythrocytes in the Perivisceral Fluid of A Holothurian
Authors: Hogben Lancelot , Van Der Lingen J.
Published: April 2021

On examining specimens of Cucumaria frauenfeldi, it was found by one of us that a red fluid exuded from the body cavity when punctured. C. frauenfeldi (Ludwig), kindly identified for us by Dr Barnard of the South African Museum, is a common representative of the Holothuroidea in the littoral fauna of the Cape Peninsula, especially abundant in rock pools at Sea Point, near Cape Town. It is dark brown in colour and about 112 to 3 inches in length. On cutting through the integument, a densely coloured fluid of a port wine red or scarlet tint exudes. A few seconds after shedding the pigment is seen to be concentrated in flocculent masses which rapidly sediment leaving the supernatant liquor colourless. It can be dispersed again by vigorous shaking, and if then transferred to a test-tube connected with a pump capable of giving a high vacuum, it changes colour from scarlet to a reddish purple on removal of air. On readmitting the latter, and shaking once more, the scarlet colour reappears, thus indicating that the colouring matter itself is a reversibly oxidisable pigment, in all probability one of the family of haemoglobins, a conclusion confirmed, as will be seen later, by spectroscopic examination.
The Effect of Electrolytes on the Muscle of the Fore-Gut of Dytiscus Marginalis, with Special Reference to the Action of Potassium
Authors: Hobson A. D.
Published: April 2021

The muscle of the isolated fore-gut of Dytiscus marginalis will maintain rhythmic contractions for long periods when suspended in a medium of the composition NaCl 0·161 M : KC1 0·003 M : CaCl2 0·002 M at a pH of about 7·2. In the presence of normal concentrations of sodium, alterations in the potassium and calcium concentrations cause changes in the muscle essentially similar to those already described by Hogben and by Wells in the crustacean heart. Rhythmic contractions can be maintained for extended periods in mixtures of potassium and calcium chlorides alone. In potassium-calcium mixtures the tone is always high, but the contractions are normal in form and the muscle reacts in the normal manner to changes in the K/Ca ratio. The optimum K/Ca ratio is extraordinarily low, having a value of about 0·4. The tone of the muscle is dependent, not only on the absolute concentration of potassium and calcium but also on the K/Ca ratio.
Active Transport of Potassium by the Cecropia Midgut
Authors: Wood J. L. , Farrand P. S. , Harvey W. R.
Published: April 2021

The potential profile recorded as a microelectrode is advanced from the blood side through the isolated midgut of Hyalophora cecropia consists of negative plateaus followed by a large positive step to the full midgut potential. Oxygen deprivation diminishes both the positive step and the midgut potential ; the negative plateaus are not affected. Changes in the potassium concentration in the blood-side solution affect both the negative plateaus and the midgut potential; the large positive step remains about the same. From these results it is concluded that the positive step is probably produced by the electrogenic potassium pump and that the negative steps are due to a potassium equilibrium potential. The discrete and independent nature of the negative and positive potentials argues that there are two barriers separating a ‘midgut’ compartment from the two bathing solutions. It is inferred that the epithelial cells are the site of the profile negativity and therefore that they constitute the ‘midgut’ compartment. This interpretation implies that the potassium equilibrium potential appears across the basal cell membranes and that electrogenic pump potential appears across the apical plasma membranes of the epithelial cells. The most conservative interpretation of these results is that the electrogenic potassium pump is located somewhere in or on the apical plasma membrane of the epithelial cells.
Kinetic Studies of the Flagellar Movement of Sea-Urchin Spermatozoa
Authors: J. Holwill M. E.
Published: April 2021

The movements of intact and glycerinated spermatozoa from two species of sea-urchin were examined in the range of temperature between.5 and 30° C. The variations of the frequency of the glycerinated spermatozoa with changing pH, dielectric constant and ionic strength were examined. From the temperature studies values for activation entropies and enthalpies were obtained that pertain to the chemical reaction which limits the frequency. Within the limits of experimental error the activation parameters are identical for the intact spermatozoa and for the glycerinated model of the same species. The results are consistent with the hypothesis that the rate-limiting reaction is the breakdown of an enzyme-substrate complex. The pH studies suggest that neither the acidic nor the basic part of the enzyme is involved in complex formation but that both participate in the breakdown of the complex. The results obtained from the studies of dielectric constant are interpreted in terms of a model for the breakdown of the enzyme-substrate complex involving the separation of several spherical charges. The studies of pH and ionic strength suggest that both 14S and 30S dynein participate in the mechano-chemical process responsible for bending the flagellum.
Water Balance in the Eggs of the Atlantic Salmon Salmo Salar
Authors: Potts W. T. W. , Rudy P. P.
Published: April 2021

The rate of exchange of tritiated water across the vitelline membrane of the eggs of the Atlantic salmon has been examined under various conditions. In eggs shed into isosmotic saline the rate constant of exchange is about 0·3−0·4/hr. When eggs are shed into distilled water or isosmotic glucose rate constants as high as 0·8−1·0/hr. occur for short periods but the rate of exchange declines rapidly. Low concentrations of sodium and more especially of calcium ions delay both the phase of rapid exchange and the phase of declining permeability. The rate of formation of perivitelline fluid is greatest during the period of high permeability.
Locomotion and Coelomic Pressure in Lumbricus Terrestris L
Authors: Seymour M. K.
Published: April 2021

Crawling movement and burrowing of Lumbricus terrestris (L.) have been studied by continuous recording of internal pressure, direct observation and analysis of cine film. Frequency of locomotory waves is from 5 to 20 per min. Timing of protrusion of setae and of backward slip of points d’appui in locomotion have been observed and recorded. In normal locomotion elongation of segments by contraction of the circular muscles gives rise to a discrete pressure pulse; shortening, by contraction of the longitudinal muscles, may or may not do so, depending on the position of the segment in the worm and the relative extent of contraction of the longitudinal and circular muscles. Consideration of crawling and burrowing pressure records emphasizes the importance of (a) the circular muscles in extension of the head end in crawling and in initial penetration of the soil, and (b) the longitudinal muscles during burrowing, in dilating the burrow and drawing in more posterior segments Mean pressures at circular and longitudinal muscle contraction are 12 and 7 cm. H2O respectively. The highest pressure recorded was 75 cm. H2O and accompanied violent squirming with evident contraction of all the body wall muscles. Resting pressures, shown in the absence of organized movement, are low (mean 0-26 cm. H2O). In both resting and crawling negative pressures sometimes occur and these are considered in relation to the inherent stiffness of the body wall and to the septate condition. Tension in the longitudinal and circular muscle layers of a worm developing 75 cm. H2O internal pressure are calculated to be 265 and 1323 g./cm.2 respectively, demonstrating in this example that, relative to the circulars, the longitudinal muscles are understressed by a factor of 5. Mean locomotory L.M. and C.M. peak values yield tension values of only 25 and 212 g./cm.2 respectively, and these are clearly well within the worm’s capacity.
The Oxygen Consumption of Octopus Cyanea
Authors: Maginniss L. A. , Wells M. J.
Published: April 2021

There is now a considerable literature on the brain and behaviour of Octopus (for reviews see Wells, 1966; Young, 1964). Most of the accounts relate to the mediterranean Octopus vulgaris and most are concerned with this animal’s behaviour in training experiments and with the effect of brain lesions on learning. These experiments have been made with octopuses of a variety of sizes, ranging from 500 g. (early experiments by Boycott & Young, 1950−55; see reviews cited above) through a ‘normal’ experimental range of 200−400 g. down to the 15−40 g. animals used in experiments dealing with statocyst removal and recognition of the orientation of objects in the visual field (Rowell & Wells, 1961 ; Wells, 1960).
Observations on the Function and Physiological Properties of a Fast Paramyosin Muscle—The Notochord Of Amphioxus (Branchiostoma Lanceolatum)
Authors: Guthrie D. M. , Banks J. R.
Published: April 2021

Measurements of tension and pressure from the isolated notochord during electrical stimulation indicate that the notochord of Amphioxus is a muscular organ. Muscular contraction increases the stiffness of the notochord and the pressure increase suggests that it behaves as a hydrostatic skeleton. The mechanical responses of the muscles accord fairly well with the known characteristics of other paramyosin muscles, although they are rather faster than the paramyosin muscles of most molluscs. The muscular response appears to make its greatest contribution to notochordal stiffness at the small angles of bending associated with fast swimming. Notochordal activation is preceded by a giant fibre potential. The collagen of the notochordal sheath appears to be rather more extensible than vertebrate collagen, but there is a material, probably in the elastica interna, with similar properties to elastin. The characteristics of the lancelet notochord emphasize rather than detract from the importance of its phylogenetic position.
Discharge Patterns of Coxal Levator and Depressor Motoneurones of the Cockroach, Periplaneta Americana
Authors: Pearson K. G. , Iles J. F.
Published: April 2021

Observation of movements of the metathoracic legs of the cockroach before and after section of peripheral nerves allowed identification of muscles involved in flexion and extension of the femur. Extracellular recordings from the nerves to these coxal muscles show that during rhythmic leg movements bursts of activity in a number of levator motor axons were strongly reciprocal and generally non-overlapping with those of a slow depressor motor axon. These reciprocal patterns persisted after removal of all sensory input from the legs. The durations of levator bursts were relatively constant compared to those of the depressor, corresponding to the behavioural observations on leg protraction time. The pattern was asymmetric: levator bursts could be generated without depressor activity, but never the reverse. No evidence was found for inhibitory collateral pathways between antagonisti motoneurones. It is proposed that levator motoneurones are driven by a group of bursting interneurones which simultaneously inhibit the ongoing depressor activity.
A Study of the Effect of Temperature Changes On the Respiratory Pumps of the Rainbow Trout
Authors: Hughes G. M. , Roberts J. L.
Published: April 2021

The pumping mechanism maintaining water flow across the gills has been investigated in the trout using pressure transducers and ciné analysis (Hughes & Shelton, 1957, 1958). It was shown that the mechanism could be considered as being made up of a buccal pressure pump and opercular suction pumps, the two being separated functionally by the gill resistance. In this species, Salmo gairdneri, the relative contribution of the two pumps appeared more or less equal, as judged by the areas of the corresponding phases of the differential pressure across the gills. Further studies of the respiratory pumps with special reference to their muscular basis were made using electromyography (Ballintijn & Hughes, 1965) and emphasized the many couplings between the two pumps. Although several studies have been made on the influence of environmental changes on gas exchange (Randall, Holeton & Stevens, 1967), no detailed account has been published on the modifications that occur in gill ventilation mechanisms and interactions with cardiac cycles when trout are subjected to stress. The present series of experiments forms part of such a study in which electrocardiograms were obtained simultaneously with electrical recordings from parts of the respiratory neurones in the medulla, from some respiratory muscles, and with pressure recordings from the buccal and opercular cavities. All were carried out during subjection of rainbow trout to warming thermal stress. A preliminary report of this work has already been given (Roberts & Hughes, 1967).
Water Balance in the Firebrat, Thermobia Domestica (Packard)
Authors: Noble-Nesbitt J.
Published: April 2021

Occlusion of the anus prevents the uptake of water from subsaturated atmospheres. It is suggested that the site of uptake is the rectum. The implications of this finding are discussed in relation to other reported cases of uptake.
Respiratory Function of the Swim-Bladders of the Primitive Fish Polypterus Senegalus
Authors: Magid A. M. Abdel , Vokac Z. , El Din Ahmed Nasr
Published: April 2021

The respiratory function of the swim-bladders of Polypterus senegalus was investigated. Experiments were carried out in tap water with an oxygen tension of about 140 mm. Hg. Both swim-bladders were cannulated through the body-walls of the unrestricted fish. Gas samples were analysed for their oxygen and carbon dioxide content before and after the fish visited the surface. A sharp increase in oxygen and a decrease in carbon dioxide tension was always observed after inhalation. This proves that atmospheric air is actually inspired into the bladders. After inspiration, the amount of oxygen in the bladders decreased rapidly. This shows that oxygen is taken up by the blood, even when the oxygen content of the water is normal. Inspiration of air is preceded by expiration which, on the average, reduces the volume of the bladders to about 40%. The uneven distribution of inhaled air in the right bladder is shown to be due to anatomical configuration.
Respiration in An Air-Breathing Fish, The Climbing Perch Anabas Testudineus Bloch
Authors: Hughes G. M. , Singh B. N.
Published: April 2021

Respiration of the climbing perch Anabas has been studied under five different experimental conditions, (a) The mean O2 consumption of a fish allowed free access to air, is about 113 c.c./kg/h at 25 °C. The fish obtain nearly equal amounts of oxygen through the gills and through the accessory organs. (b) The overall O2 consumption from water of a fish allowed free access to nitrogen is nearly the same as during normal respiration from water with access to air. (c) The O2 consumption is reduced when the fish is out of water and obtains all its oxygen from air. (d) The O2 consumption from air increases considerably when the fish is maintained in de-oxygenated water and depends upon surfacing for its oxygen supply, (e) The O2 consumption of a fish kept in aerated water and prevented from surfacing remains at a minimum level relative to the other four conditions. Much more carbon dioxide is released through the gills than through the accessory organs (10:1) when the fish respires from aerated water with access to air. The accessory organs are much more important for O2 uptake. The respiratory quotient is approximately 1 when the fish is in aerated water, with or without access to air, but is only 0·7 when the fish is out of water. Anabas can live out of water for 6–10 h if protected from dehydration. It continues to breathe quietly in air-saturated water using its gills alone for shorter periods (6–8 h) when denied free access to air.
Properties of Action Potentials from Insect Motor Nerve Fibres
Authors: Pearson K. G. , Stein R. B. , Malhotra S. K.
Published: April 2021

The properties of nerve action potentials in small insect motor nerves were studied using extracellular recording electrodes. A length of nerve was lifted out of solution and recordings were made with respect to the solution either from an intact nerve (triphasic recording) or from near a cut end of the nerve (monophasic recording). In a cockroach nerve, the number of spontaneously active fibres was small enough that corresponding nerve fibres could be identified in each preparation by their action potential amplitude and their pattern of activity. Under controlled conditions, the absolute amplitudes of either monophasic or triphasic records were reproducible and could be used to calculate fibre diameter. The calculations were confirmed from histological sections of the nerve. Conduction velocity varied approximately as the 0·78 power of fibre diameter in a cockroach nerve and as 0·7 power of fibre diameter in a locust nerve. These values are considerably larger than the square root relation predicted if membrane properties are independent of fibre diameter. Membrane properties probably vary with fibre diameter since the action potential duration increases dramatically for fibres below 5 μ in diameter. For the cockroach nerve systematic structural differences between fibres of different sizes are also seen with the electron microscope and the relation of these to the functional differences is considered.
Regulation of Cellular Osmolarity and Volume in Tetrahymena
Authors: Stoner Larry C. , Dunham Philip B.
Published: April 2021

Tetrahymena pyrifor mis are hyperosmotic to external media of osmolarities from 2 to 171 m-osmole/1. The intracellular osmolarity, determined by freezing-point depression, is 111 m-osmole/kg cells in dilute media, and increases linearly with increasing external osmolarities. Over 80% of the intracellular osmolarity can be attributed to the concentration of sodium, potassium, chloride and the free amino acids. In response to an increase in the external osmolarity, Tetrahymena regulates its intracellular osmolarity by increasing the concentrations of free amino acids. The regulation of cellular volume under conditions of osmotic stress is achieved by an increase in the amount of osmotically active solutes and the regulation of the rate of elimination of fluid by the contractile vacuole.
The Effects of Laser Microbeam Irradiation On the Flagellum of Crithidia (Strigomonas) Oncopelti
Authors: Goldstein S. F. , Holwill M. E. J. , Silvester N. R.
Published: April 2021

Flagella and cell bodies of Crithidia (Strigomonas) oncopelti were irradiated at preselected points with a pulsed ruby laser microbeam. Results were recorded by high-speed cinephotomicrography. A flagellum could be completely amputated at the irradiated point. The portion of the flagellum between the cell body and the irradiated point beat from the base after irradiation. The amputated portion of the flagellum could beat from either the tip or the irradiated point, and could beat first from the tip and then from the irradiated point or vice versa. Beating could continue for up to ten cycles. For flagellar activity in this organism neither a unique region of the flagellum nor the cell body is necessary. Wave propagation appears to involve the transmission of a signal at a greater velocity than that of the wave. The results favour a model of bend propagation which allows for a distribution of autonomous initiators along the flagellar length.
Symmetry and Non-Linearity of Osmotic Flow Across Rectal Cuticle of the Desert Locust*
Authors: Phillips J. E. , Beaumont C.
Published: April 2021

A method for measuring osmotic flow of water across rectal cuticle of the desert locust in vitro is described. The osmotic permeability coefficient decreases as the average osmolality of the two bathing solutions increases, probably due to dehydration of the cuticle. This is supported by a corresponding decrease in the diffusion permeability coefficient, as measured by flux of tritiated water in the absence of osmotic flow. Osmotic permeability is at least fifty times greater than diffusion permeability. This supports the hypothesis that osmotic flow occurs by bulk flow or single-file diffusion through pores. Isotopic flux measurements during net flow support this view. The osmotic permeability of the cuticle differs by less than 25% if at all, in the two directions of flow; that is, rectification or ‘valve-like’ behaviour is not significant. The cuticle represents only 2·6 to 13% of the total resistance to osmotic flow across the whole rectal wall and is not responsible for the asymmetry of the latter. Application of Beament’s model for water transport to the rectal wall of insects can be excluded in the case of the desert locust.
Factors Regulating the Discharge Frequency in Optomotor Fibres of Carcinus Maenas
Authors: Wiersma C. A. G. , Fiore L.
Published: April 2021

The influence of the excited state of the animal on various motor neurone discharges and accompanying muscle action potentials was studied in the eyestalk of the crab, Carcinus maenas. In most cases large increases in firing frequency could be obtained during such states. An exception is the tonic eye-withdrawal system in which an inhibitory effect is caused. A pronounced difference in habituation to constant stimuli between spring and summer was found for the position fibres; in spring it was slow and in summer much quicker.
The Effect of Thermal Acclimation On the Heat Tolerance of the Intertidal Prosobranchs Littorina Littorea (L.) and Monodonta Lineata (Da Costa)
Authors: Newell R. C. , Pye V. I. , Ahsanullah M.
Published: April 2021

The effect of exposure time and acclimation temperature on the survival of the winkle Littorina littorea and the topshell Monodonta lineata is described. It was found that acclimation to temperatures between 5 and 16°C enhanced survival whereas acclimation to temperatures above 21°C resulted in little further elevation of the heat-lethal temperature. The process of thermal acclimation is accomplished by raising the heat tolerance of the less-resistant individuals more than that of other members of the population. The increase in sea temperatures which occurs with the onset of summer is sufficient to extend the thermal tolerance so that unusually high temperatures can be tolerated when the animals are uncovered by the tide.
Coxal Depressor Muscles of the Cockroach and the Role of Peripheral Inhibition
Authors: Iles J. F. , Pearson K. G.
Published: April 2021

Mechanical properties of the coxal depressor muscles of cockroaches have been studied and found to be compatible with the pattern of innervation determined by microelectrode recording. During walking activity excitatory and inhibitory axons to the slow depressor muscles are alternately active in bursts. Firings of the three inhibitory axons are positively correlated. The rate of relaxation of the slow muscles is increased by activation of the inhibitory axons innervating them. It is proposed that one functional significance of peripheral inhibition in insects is to increase the rate of relaxation of slow muscles used in rapid movements.
Electrical Correlates of Ciliary Reversal in Oikopleura
Authors: Galt C. P. , Mackie G. O.
Published: April 2021

Reversal of the water current through the pharynx of Oikopleura is brought about by a change in the action of the cilia of the two stigmatal ciliated rings. These ‘ciliary reversals’ occur synchronously in the two ciliated rings and can be evoked by the addition of particulate material to the incoming water or by tactile or electrical stimulation of the lips. Nerves run from the lips via the brain to individual ciliated cells, and it is therefore likely that the ciliated cells are under nervous control. At each ciliary reversal an electrical potential can be picked up on the body surface. The same events are recorded by microelectrodes inserted into the ciliated rings. The microelectrode recordings resemble intracellular recordings, and the reversal potentials are considered to represent depolarizations of the membranes of the ciliated cells. Ciliary reversals continue after removal of the brain, suggesting the existence of a peripheral pacemaker.
Preliminary Observations on the Ionic Regulation of the Arctic Char Salvelinus Alpinus
Authors: Roberts R. A.
Published: April 2021

The degree of euryhalinity in a fresh-water resident population of the arctic char, Salvelinus alpinus, has been determined. Although isolated in fresh water for c. 10000 –12000 years these fish still show a high degree of salinity tolerance characteristic of their ancestral stock, but this is variably developed in individuals. In fresh water, blood sodium concentration is regulated at 150 mM/1 and chloride at 130 mM/1. These increase to 233 and 218 mM/1 respectively in sea water. Fish in sea water show a large increase in muscle sodium, although the potassium concentration is only slightly higher than that maintained in fresh water. The total sodium content of the fish reflects the increase observed in the intracellular and extracellular compartments. The rate of sodium turnover in sea-water-adapted fish is some ten times higher than in fresh-water-adapted fish, although it is significantly lower than that observed in most sea-water-adapted teleosts.
The Effect of Environmental Calcium and Ovine Prolactin on Sodium Balance in Fundulus Kansae
Authors: Potts W. T .W. , Fleming W. R.
Published: April 2021

The sodium contents and rates of turnover of sodium have been determined in both intact and hypophysectomized Fundulus kansae in a variety of media. A reduction of the calcium content of fresh water from 1·0 to 0·1 mM/1 increased the rate of sodium efflux by half while transter to calcium-free water increased the rate several fold. The rate of sodium efflux increased fourfold in sea water containing no magnesium and only 1 mM/l calcium. Hypophysectomy increased the rate of efflux in fresh water but reduced it in sea water. Intact fish adapted to sea water and treated with prolactin showed a net gain of sodium probably due to a reduction in the activity of the sodium efflux pump. Both intact and hypophysectomized fish on transfer from sea water to fresh water reduced the rate of efflux of sodium in a series of stages. Studies of the rate of efflux of sodium before and after transfer between various media showed no evidence of exchange diffusion or of a linked sodium-potassium efflux pump, but did show evidence or interaction between sodium and chloride fluxes probably as a consequence of potential changes. The rate of efflux of sodium from F. kansae doubled following hypophysectomy. The ability of hypophysectomized F. kansae to survive in fresh water after hypophysectomy, unlike F. heteroclitus, is due to a more effective uptake system.
The Organization of Escape Behaviour in the Crayfish
Authors: Wine Jeffrey J. , Krasne Franklin B.
Published: April 2021

Invertebrate escape reflexes have long been favoured preparations for investigating neuronal substrates of behaviour. The large size of many of their component neurones make them accessible to current micro-electrode techniques, and selection pressures for rapidity of response have probably caused them to evolve in the direction of the maximal neurological simplicity consistent with their function. Indeed, given our current technical and conceptual limitations, they are probably among the very few behaviour patterns that we may presently hope to analyse with any degree of completeness.
Adaptation in the Compound Eye and Interaction with Screening Pigment
Authors: Yinon U.
Published: April 2021

The electroretinogram pattern in the compound eye of T. molitor and the appearance of irregular small potentials and spikes superimposed on the ERG are influenced during dark and light adaptation procedures.

The amplitude of the principal negative potential reflects bleaching and recovery of the photochemical process. This is not true for the latency values. The delay of the electrical response increases in the dark and decreases in the light adapted eye. These changes were influenced by the intensity of the adapting light.

Mutant eyes only lack screening pigment and have normal visual neural pathways. The absence of this pigment lowered the threshold sensitivity of the unscreened eye in dark adaptation. The difference between the adaptation processes in mutants and normal animals has been suggested as a criterion for measuring the net effect of the screening pigment in the compound eye.
A Study of the Function of the Neural Fat-Body Sheath in the Stick Insect, Carausius Morosus
Authors: Treherne J. E.
Published: April 2021

The effects of variation in the sodium concentration of the bathing media on axonal function has been measured in de-sheathed connectives in the presence of the overlying neural fat-body sheath. The response to solutions of the same sodium concentration as the haemolymph (15 mM/1) was found to be essentially similar to that recorded in de-sheathed connectives in the absence of the fat-body sheath, there being a rapid decline in amplitude of the recorded action potentials in both preparations. On the basis of these observations it is concluded that the neural fat-body sheath is unlikely to be involved in the regulation of the extra-neuronal sodium level.
The Corpus Allatum and Oogenesis in Rhodnius Prolixus (Stål.)
Authors: Pratt G. E. , Davey K. G.
Published: April 2021

In females which have been re-fed after various periods of fasting there is a delay in the resumption of ovarian growth which becomes greater with longer periods of starvation. In females kept without food for 28 days before re-feeding, vitellogenesis is not resumed until 4 or 5 days after the meal, whereas the concentration of yolk antigen in the haemolymph returns to its normal level by the third day after the meal. A period of starvation induces an accumulation of oocytes in the size range below that of activation until the fourth or fifth day after re-feeding, when the terminal oocytes pass rapidly through the critical size range and enter vitellogenesis. The tropharia of starved females exhibit a remarkably reduced affinity for the protein stain Ponceau S, and enlarged trophocytes with their characteristic inclusions are absent during the first 6 days after re-feeding.