bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Visual System of Nautilus Pompilius
Authors: Muntz W. R. A. , Raj U.
Published: April 2021

The anatomy of the eye of Nautilus pompilius Linnaeus was studied, using light and electron microscopy. The outer and inner surfaces of the iris were found to be lined with columnar epithelium bearing microvilli, except for the groove running ventrally from the pupil over the outer surface of the iris, where the epithelial cells bear cilia. Many mucus cells are also present.

The epithelium of the inner surface of the iris merges smoothly with the retina. There is no significant variation in receptor packing or rhabdome length between different parts of the retina. Screening pigment is present, but shows no photomechanical movements in response to light. Immediately beneath the retina the nerves are collected into well-organized bundles, which run in a direction suggesting that they may form an optic chiasma analogous to that found in other cephalopods.

Visual acuity was also determined, using the optomotor response. The minimum separable angle was found to lie between 11·25 and 5·5°. This agrees well with the value expected on the basis of the gross dimensions of the eye and pupil, and also with expectation based on photographing a visual test chart with a scale model of the eye. It is, however, considerably worse than would be expected from the dimensions of the receptor mosaic.
Potentials Associated With the Blood-Brain Barrier of an Insect: Recordings from Identified Neuroglia
Authors: Schofield P. K. , Swales L. S. , Treherne J. E.
Published: April 2021

The blood-brain barrier of the insect nervous system is thought to be formed by the neuroglia. It is associated with a positive interstitial potential relative to the bathing medium (‘sheath’ potential), and with positive changes in potential that can be induced by raising the potassium level in the bathing medium. In central nervous connectives of the cockroach, Periplaneta americana, these potential differences (p.d.s) were measured just below the perineurium at the same magnitude as comparable p.d.s recorded deeper, indicating that they are produced by the perineurium. The interstitial p.d. apparently results from the presence of a paracellular resistance, and from the generation of less electromotive force (e.m.f.) by the basolateral membrane than by the apical (adglial). Recordings from cells identified by injection of peroxidase showed that the initial change in interstitial p.d. induced by high K was accompanied by: a depolarization of greater magnitude across the basolateral membrane, a small depolarization of the apical membrane, and no depolarization of sub-perineurial glial cells or axons. It therefore appears that the depolarization of the basolateral membrane by high K gives rise, by electrical coupling, to the shift in interstitial p.d. and the depolarization of the apical membrane. There was then a gradual depolarization of all membranes, consistent with a leak of K into the sub-perineurial interstitial system, and where the depolarization of the basolateral membrane would be produced by coupling to the apical. If the perineurium contains an intercellular resistance, then it must restrict diffusion of water-soluble substances.
Localization of the Blood-Brain Barrier of an Insect: Electrical Model and Analysis
Authors: Schofield P. K. , Treherne J. E.
Published: April 2021

The perineurium was found to form the principal barrier to diffusion across the blood-brain barrier system of the cockroach, Periplaneta americana, since the resistance across this layer was much greater than that across the underlying neuroglia. An equivalent electrical circuit of the perineurium was then used to analyse recordings made in apparent perineurial cells and the interstitial system. Trans-perineurial resistance was at least 900 Ω cm2, while the ratio between basolateral and apical membrane resistances was 11:1, indicating that the apical membrane had an area much greater than that of the basolateral membrane. Raising the potassium concentration in the saline produced changes in potential difference (p.d.) and resistance that were interpreted as due to the effect of potassium upon the basolateral membrane. Analysis indicated that the resting electromotive force (e.m.f.) generated by the basolateral membrane was less than that generated by the apical, although the K level in the saline was near that considered to be in the interstitial system. The analysis also yielded a value of 9 for the ratio of shunt resistance to apical resistance. Most changes in recorded values following the K elevation could be simulated by use of the estimated parameters, and an estimation of a change in interstitial K level. From these results, the shunt can be calculated to be an important contributor to the resistance across the perineurium, having a resistance about 0·9 times that of the transcellular resistance.
Quantitative Analysis Of Cellular and Paracellular Effects Involved in Disruption of the Blood-Brain Barrier of an Insect by Hypertonic Urea
Authors: Schofield P. K. , Swales L. S. , Treherne J. E.
Published: April 2021

Brief exposure of central nervous connectives of the cockroach, Periplaneta americana, to 3 M-urea, a treatment known to increase the leak of cations across the blood-brain barrier system, caused a reduction in the resistance and potential difference (p.d.) across the perineurium, which forms the principal component of the barrier. There was also a reduction in the p.d. across the apical membrane of perineurial cells which might indicate a higher interstitial potassium level. There was no effect upon the p.d. recorded across the basolateral membrane of the cells, but there was some reduction in the ratio between the resistances of the basolateral and apical membranes. When the potassium level in the saline was raised, the depolarization of the basolateral membrane was less reduced by urea than the change in p.d. across the perineurium. During high K, the gradual depolarization of the perineurial membranes was speeded by urea treatment, as was the change in axon resting potential, as to be expected with more rapid entry of K into the interstitial system. Analysis of the initial effects of high K upon the electrical characteristics of the perineurium indicated that urea had reduced the resistance of the paracellular pathway by 73 % and the resistance of the basolateral membrane by 44%. Most of the electrical events in urea-treated preparations could be simulated from the estimated parameters and an estimation of the rise in interstitial K level during the high K exposure. The study indicates that the increased leak across the perineurium caused by urea treatment results chiefly from a decrease in intercellular restriction.
Oxygen consumption and luminescence of Porichthys photophores stimulated by potassium cyanide
Authors: Mallefet J. , Baguet F.
Published: April 2021

Isolated photophores of Porichthys notatus, maintained in saline at 20 °C, do not luminesce and show an oxygen consumption rate of 0·07 ± 0·01 nmol min−1 photophore−1. In the presence of 10−6 M-KCN, the photophores do not luminesce but the resting respiration decreases by about 50%. In the presence of 10−5 M-KCN, some photophores do not luminesce and their respiration rate decreases by about 75 %. Others show a response and resting oxygen consumption slowly increases. At high concentration (10−4 and 10−3 M), KCN induces a large light emission and increase in oxygen consumption. The stimulatory effect of KCN on the photophore oxygen consumption is tentatively explained by an activation of the luciferin-luciferase system by calcium ions.
A possible role of the kidney and urinary bladder in urea conservation of Bufo viridis under high salt acclimation
Authors: Katz U. , Ben-Sasson Y.
Published: April 2021

The toad Bufo viridis can be acclimated to high salt solutions up to 800 mosmol kg−1 of NaCl (Tercafs & Schoffeniels, 1962; Katz, 1973). Despite extensive studies on various aspects of adaptation to high salt in this species (Gordon, 1962; Katz, 1979; Katz, Garcia-Romeu, Masoni & Isaia, 1981) only little attention has been paid to the osmoregulatory roles of the kidneys and urinary bladder during high salt acclimation. In/tana cancrivora, a species which can be acclimated to salinities even higher than B. viridis (and which shares the property of urea accumulation) Schmidt-Nielsen & Lee (1962), found a lower urine flow under high salt and consequently reduced urea secretion, while Gordon & Tucker (1968) observed urea retention at first, but increasing loss at salinities higher than 400 mosmol kg−1. Ferreira & Jesus (1973), presented evidence in salt adapted B. bufo suggesting increased osmolarity (mainly sodium) in the urinary bladder. We therefore attempted to assess the turnover of water and urea in B. viridis with special emphasis on the contribution of the renal and the urinary bladder.
The Control of Respiratory Movements in Crustacea by Oxygen and Carbon Dioxide
Authors: Fox H. Munro , Johnson M. L.
Published: April 2021

The respiratory movements of the barnacle Balanus and of the phyllopod Cheirocephalus are not accelerated either by decreased oxygen or by increased carbon dioxide tension in the water. The rate of movement of the scaphognathite of the crayfish Astacus is accelerated by a fall in oxygen but not by a rise in carbon dioxide tension of the environment. The rate of movement of the pleopods of the fresh-water isopod Asellus is accelerated by a fall in oxygen but not by a rise of carbon dioxide tension. In the sea-shore isopod Ligia, submerged in sea water, the rate of pleopod movement is not accelerated by a decrease in oxygen tension below that in equilibrium with air, but a rise in oxygen tension above the latter value slows respiratory movements. Carbon dioxide has no accelerating effect. Both a decrease in oxygen and an increase in carbon dioxide tension accelerate the respiratory pleopod movements of the amphipods Gammaruspulex and G. locusta. Whereas in the fresh-water G. pulex the quickened respiratory rhythm is permanent at each decreased oxygen and increased carbon dioxide tension, in the marine G. locusta these changes in rate of beat are transitory. This is correlated with the greater oxygen consumption of the marine species.
Some Observations on Potential Differences Across the Ectoplasm Membrane of Paramecium
Authors: Kamada Takeo
Published: April 2021

As might be expected, a measurable potential difference is found between a pair of micro-electrodes, one of which is inside a Paramecium and the other in the external medium. The magnitude of this potential depends on the nature of the external solution. A brief account of the influence of the environment on the nature of the potential observed is given in the following pages.
The Absorption and Accumulation of Solutes By Living Plant Cells
Authors: Steward F. C. , Berry W. E.
Published: April 2021

Discs cut from plant storage organs have long been favourite material for experiments upon salt absorption. A recent series of papers (Steward, 1932 a–c, 1933 ; Steward, Wright and Berry, 1932) which refers especially to potato tissue indicates that in the past the attention directed to the respiration of these tissues was far too scanty. With the development of an adequate technique (Steward, 1932 b) the general principles operating in the case of potato tissue became increasingly apparent, and the occasion thus arose to extend the investigations to other storage organs. A survey of several storage organs (Berry and Steward, 1934) revealed that discs cut from artichoke tubers combined a conspicuous ability to absorb the salt studied (KBr) with a characteristic respiratory behaviour which presented features somewhat different from those of potato. The present paper records an attempt to ascertain whether the observed behaviour in respiration is reflected in salt absorption in the manner anticipated and to determine further details of the absorption process, with particular reference to potassium bromide and artichoke tissue. A matter which received some special attention was to ascertain whether the absorbed salt replaces ions already within the cell, or accumulates, against a concentration gradient, in the vacuole where it exists in true solution without displacing other ions. Since they were obtained, the results here presented have gained added interest in the light of the results published by Briggs and Petrie (1931) and, more particularly, in view of a theoretical interpretation of absorption by cells (Briggs, 1932) based upon ionic exchange.
The Function of the Antennae inRhodnius Prolixus(Hemiptera) and the Mechanism of Orientation to the Host
Authors: Wigglesworth V. B. , Gillett J. D.
Published: April 2021

Anyone who has handled the blood-sucking bugs, Triatoma or Rhodnius, must have observed that they are often attracted to the sides of their jars at places where these have been warmed by recent handling, and that they will probe such spots vigorously with the proboscis. This behaviour suggests that they are attracted to their host mainly by warmth1—a belief which is supported by the recent observations of Rivnay (1932) on the bed bug (Cimex) and of Hase (1932) on various Triatomidae. Further, the movements of the antennae, which precede the location of the host, suggest that these carry the sense organs concerned ; and we were led to undertake the present work because it seemed possible that Rhodnius might prove a favourable subject in which to study both the function of the antennae, and the mechanism by which they secure the orientation of the insect in relation to its host. More particularly we hoped to define this mechanism in terms of the current theories of orientation (Loeb, 1918; Kühn, 1919; Fraenkel, 1931).
Observations on the Fatty Constituents of Marine Plankton
Authors: Drummond J. C. , Gunther E. R.
Published: April 2021

In view of the relations which are believed to exist between the vitamin content of the diet and that of the fats stored in an animal’s body it is of considerable interest to examine the oils separated from phytoplankton and zooplankton respectively. The isolation of the oils and the results of their general chemical examination are described in a preceding paper (Collin, 1934).
Experiments on Embryonic Induction
Authors: Waddington C. H.
Published: April 2021

It is shown that the ectoderm of the area opaca of chick embryos of the primitive streak stage can react to primitive streak grafts by the formation of an induced neural plate. The conclusion is drawn that the competence to form neural plate is not conferred on ectoderm by the gut endoderm, which determines the formation of the primitive streak.
Experiments On Embryonic Induction
Authors: Waddington C. H.
Published: April 2021

The work of Waddington and Waterman (1933) has shown that it is possible to cultivate young rabbit embryos in vitro, using the normal watch-glass technique and a medium composed of chicken embryo extract and either chick or rabbit plasma. Micro-surgical operations can be performed on such embryos before they are explanted into culture, and the mutual interactions of the various embryonic rudiments can be investigated in this way. It may eventually be possible to obtain as complete an account of the developmental mechanics of the mammalian embryo as Spemann and his school have provided in the Amphibia, but it is probable that operations on the mammalian embryo will always be attended with considerable difficulty. Apart from the laboriousness of the tissue culture technique with its concomitant necessity for absolute sterility, the rabbit embryo, if not every mammalian embryo, is very difficult to handle owing to its transparency, toughness and stickiness. The transparency of the blastocyst and embryonic shield in the primitive streak stage makes it difficult to distinguish exactly the various embryonic organs ; the toughness of the tissue hinders neat cutting and operating ; while the stickiness of the cells is probably the most annoying characteristic of all, since it results in any fragment of tissue, which may for example be intended for a graft, adhering to the operating knives with such tenacity that it frequently becomes entirely macerated during the attempts made to free it.
On the Digestion of Wood by Insects
Authors: Mansour K. , Mansour-Bek J. J.
Published: April 2021

The true wood-feeding insects do not depend on micro-organisms for the digestion of wood. Such insects are of two types: Without cellulose-breaking enzymes. Insects of this type derive the necessary carbohydrates from the soluble sugars and starch in the wood they live on, and consequently such insects can only live in kinds of wood comparatively rich in these substances. With cellulose-breaking enzymes. Insects of this type can utilise the cellulose of the wood through the activity of their own secretions. They therefore can live on woods very poor in the simpler carbohydrates. Wood-eating insects with free-living intestinal micro-organisms (such as the termites and the Lamellicorn larvae) use the micro-organisms as direct food and derive no digestive help from them. Insects of this type are better referred to as micro-organism feeding.
On The Relation of the Thyroid Gland to Metamorphosis in the Lamprey
Authors: Horton Frances M.
Published: April 2021

Ammocoetes were treated with iodine, potassium iodide, iodoform and thyroid extract solutions. No metamorphosis was induced. Injections into ammocoetes of iodoform and of thyroid extract were made, without any metamorphic changes appearing. Lamprey, ammocoete, and ox thyroids were grafted into tadpoles. Lamprey and ox thyroid were equally active in accelerating metamorphosis, but the ammocoete gland has no such effect. The glands of sixty ammocoetes were analysed for iodine. They contained none. The effect of iodine and thyroid on ammocoete respiration was tested. In no case was the oxygen consumption increased. It is concluded that the thyroid gland has no significance in the metamorphosis of the lamprey.
The Effect of Suckling on the Duration of Pregnancy in the Rat (Wistar Albino)
Authors: Hain A. M.
Published: April 2021

It is an established fact that in the mouse and rat ovulation normally takes place between 12 and 32 hours after parturition (Long and Evans, 1922). Only rarely, however, does a pregnancy result from a mating at this time if the mother is suckling a litter (Kirkham, 1916), and in those instances where a second pregnancy does ensue it is of longer duration than is the case in the normal non-suckling animal. Daniel (1910) was of the opinion that an exact relationship existed between the number of young suckled and the extent by which gestation was prolonged. The absence of any such correlation was demonstrated by Kirkham (1916), who also investigated the cause of the prolongation of pregnancy in such cases. This was found to be due to a delay in implantation of the ova released at the post-partum ovulation, a delay which he ascribed to the inhibitory action of the mammary glands upon the uterus; he recognised that this activity was modified by the metabolic idiosyncrasies of the individual.
Notes on Ovulation and Fertilisation in the Ferret
Authors: Hammond J. , Walton A.
Published: April 2021

The ferret ovulates normally about 30 hours after coitus. The average duration of coitus is about 2 hours but varies from 14 hour to 3 hours. There was no evidence that short copulations were less fertile than long ones. For 36 hours after coitus the vulva remains turgid, but becomes flaccid by about 60 hours after coitus, presumably from absence of oestrin. Spermatozoa reach the upper part of the uterus within about 3 hours after coitus, but during this time do not reach the ovarian capsule. Spermatozoa were found in the ovarian capsule 6 hours after coitus. No spermatozoa were found in the ovarian capsule or uterus 10 days after coitus. An attempt to determine the possible duration of fertilising capacity of the spermatozoa in the female tract was made, but no conclusive results were obtained owing to the difficulty of performing artificial insemination in the ferret. In the ferret the ovum remains capable of fertilisation for not more than 30 hours after ovulation. From 18 to 30 hours after ovulation only a small proportion of the ova remain capable of fertilisation, and small litters are produced from matings made at this time.
The Water Relations of Snails and Slugs
Authors: Howes N. H. , Wells G. P.
Published: April 2021

In the first paper of this series (Howes and Wells, 1934), we showed that active specimens of the edible snail (Helix pomatia) continually undergo considerable fluctuations in weight, due to changes in their water content, even in environments which do not greatly vary in physical properties. The following experiments were performed in order to find out whether similar phenomena occur in slugs. Most of the experiments were done on Arion ater, but specimens of Limax flavus were also studied. The results obtained on the two species will be described separately and then discussed together.
Osmotic Regulation in Gunda Ulvae
Authors: Beadle L. C.
Published: April 2021

The triclad turbellarian Gunda ulvae in its normal habitat is daily subjected both to sea water and to pure stream water. Under experimental conditions it can live permanently in any concentration of sea water down to 5 per cent. It is thus able to maintain a relatively constant internal against a rapidly changing external environment. The manner in which this is done is suggested by the results of the above experiments, from which it is concluded that the following is the course of events when the animal is transferred from pure to dilute sea water (e.g. 10 per cent.): (a)An initial inflow of water through the ectoderm into the parenchyma which causes swelling and a temporary lowering of activity.(b)This water is taken up by the gut cells in the form of intracellular vacuoles, a process which entails expenditure of energy and can be inhibited by cyanide. The parenchyma is thus restored to its original condition and full activity is recovered.(c)After the initial inflow of water the animal begins to set up a resistance, which appears to be effected by a decrease of permeability to water of the ectodermal membrane.(d)This resistance is maintained and the gut cells remain vacuolated so long as the animal is kept in dilute sea water. The excretory (water-vascular) system plays no obvious part in this mechanism. Distinction must be drawn between the ultimate impermeability of the ectoderm considered as a membrane and the osmotic resistance of the individual cells of this layer and of the other tissues. The permeability of the ectodermal membrane can be reversibly increased by calcium deficiency, but the osmotic resistance of its individual cells cannot be broken down by these means. This can be brought about by decreasing the osmotic pressure of the water to that of 2 per cent, sea water. Under these conditions the presence of calcium may retard but does not prevent the final swelling and disintegration of the cells, a process which is irreversible. It is suggested that both vacuole formation by the gut cells and the osmotic resistance set up by the individual cells of the other tissues are active processes entailing expenditure of energy, whereas the resistance of the ectodermal membrane to inflow of water into the parenchyma is a passive impermeability.
The Function of the Antennae in Rhodnius Prolixus: Confirmatory Experiments
Authors: Wigglesworth V. B. , Gillett J. D.
Published: April 2021

The conclusion, previously arrived at, that Rhodnius prolixus responds to the gradient of air temperature around the source of stimulus, and not to radiant heat, was based on false premises; but this conclusion has now been confirmed by further experiments.
The Effect of Irradiation With Different Wave-Lengths on the Oestrous Cycle of the Ferret, With Remarks on the Factors Controlling Sexual Periodicity
Authors: Marshall F. H. A. , Bowden F. P.
Published: April 2021

The ferret normally has a well-marked breeding season extending from about the middle of March until July or August, March 2nd being the earliest date in our experience for a normal ferret to come “on heat.” Oestrus in the non-occurrence of pregnancy or pseudo-pregnancy lasts a very long time and has been known to persist for 17 weeks. The condition is particularly easy to detect owing to the enormous swelling of the vulva which may be fifty times its anoestrous size. After ovulation which depends upon coitus the vulval swelling subsides as oestrus comes to an end. Pregnancy lasts about 42 days and there can be two gestation periods in the season (Marshall, 1904; Hammond and Marshall, 1930). The polecat in the wild state has a breeding season at approximately the same time as that of the ferret in captivity (Millais, 1905).
Growth and Ion-Specificity of Excitability in Regenerating Cockroach Giant Interneurones
Authors: Leech C. A. , Treherne J. E.
Published: April 2021

The effects of lesions on cockroach giant interneurones (GIs) were studied to investigate the transient, Ca-dependent, action potentials which have been reported to appear near the tips of regenerating’GIs (Meiri, Spira & Parnas, 1981). We were unable to repeat these observations.

Ligation of connectives, before cutting, delayed the degenerative changes in segments of GIs that were separated from their cell bodies. The shortterm injury response (which was normally observed on cutting while recording close to the site of lesion) was not recorded when the axon was ligated.

The effect of cutting GIs at different distances from their cell bodies was also investigated. There was no apparent relation between the response of GIs to a lesion and the site of the lesion.

Sprouting of GIs was observed both at the tip of the axon and also at sites some distance from the lesion. No changes of the cell body or its dendritic tree in the terminal ganglion were seen but sprouting was observed in other ganglia.
A New Method Measuring Leg Position of Walking Crustaceans Shows that Motor Output During Return Stroke Depends Upon Load
Authors: Cruse H. , Müller U.
Published: April 2021

The basic movement of a walking leg consists of two parts, the power stroke (stance phase) and the return stroke (swing phase). The movement of a leg during the power stroke is determined not only by the sensory-neural system of the leg itself but also by the movement of the other supporting legs because of their mechanical coupling. In contrast the movement during the return stroke is under the sole control of the sensory-neural system of the leg itself. Therefore observation of the return stroke movement allows a more direct view of the motor output from the centre controlling the movement of the leg. Motor output can be recorded by electrophysiological methods. However, quantitative interpretation of these results is often difficult as the transformation of the recorded spikes (often from several superimposed motor units) to force is usually unknown. Whereas motor output during the power stroke clearly depends on walking speed and on load, some studies have found return stroke duration to be dependent upon walking speed, others found no such dependence (for reviews see Clarac, 1981; Evoy & Ayers, 1982). A solution to this discrepancy has been proposed on the basis of a model which assumes that load is an essential parameter affecting the movement of the individual walking leg (Cruse, 1983). A central assumption in this model is that motor output during both power stroke and return stroke is increased when the animal walks under load. It follows from this assumption that an increase in the load should lead to faster return stroke movements and, for constant leg amplitudes, to shorter return stroke durations. As mentioned above this prediction can be easily tested for the return stroke. Therefore, we developed a simple method to measure return and power stroke durations and step amplitude for a decapod walking under water.
Oxygen Consumption in Swimming Salps (Tunicata: Thaliacea)
Authors: Trueman E. R. , Bone Q. , Braconnot J-C.
Published: April 2021

The pelagic salps swim in a regular rhythmic manner, by contracting their muscle bands and so emitting propulsive jets of water from the tubular body. Since they will continue to swim when confined in small chambers in which their oxygen consumption can be measured whilst their activity is monitored, it is possible to make direct estimates of the energetic cost of locomotion, and to compare these with estimates derived from the hydrodynamics of the process (Bone & Trueman, 1983). We show here that salp locomotion is an economical process, and that respirometric and hydrodynamic estimates of the energy expended are in good agreement.
Calcium Metabolism in Embryos of the Oviparous Snake Coluber Constrictor
Authors: Packard Mary J. , Packard Gary C. , Gutzke William H. N.
Published: April 2021

Total calcium in embryos of an oviparous, colubrid snake (Coluber constrictor L.) rises rapidly during the last half of incubation as the embryos increase in size. Although most of this calcium is drawn from stores in the yolk, hatchlings contain more calcium than was present in yolk of eggs at oviposition. Because shells from eggs incubated to hatching contain less calcium than do shells from freshly-laid eggs, the extra calcium appears to be drawn from the eggshell. Indeed, approximately 20% of the calcium required for development in this snake is obtained from the eggshell, with the remainder coming from the yolk. Thus, embryos of oviparous snakes, like embryonic chelonians, crocodilians and birds, withdraw calcium from their eggshells and do not rely exclusively on calcium supplied in their yolk for support of growth and development.
Urine Formation in the Lamellibranchs: Evidence for Ultrafiltration and Quantitative Description
Authors: Hevert F.
Published: April 2021

Physical and chemical parameters were measured in the Japanese oyster Crassostrea gigas to investigate whether the first step of urine formation in the lamellibranchs could be an ultrafiltration and to give a quantitative description. The effective filtration pressure was not constant, but a function of time, oscillating between 31·7mmH2O and −3·8mmH2O. During the filtration, a separation of proteins took place: the protein concentration in the haemolymph was 17μmoll−1 and the average molecular weight was 141000. In the filtrate, the protein concentration was 2μmoll−1 and the average molecular weight was 45 000. The marker substance inulin, applied via the gills, appeared successively within the haemolymph and the pericardial fluid. These findings establish the idea that the pericardial fluid is formed by ultrafiltration from the haemolymph. The rate of filtration was found to be 0·4μlg−1 min−1 by quantitative analysis of the transport of the inulin. The coefficient of filtration was 4·5× 10−6mls−1cm−2mmHg−1.
Neurohormonal Modulation of the Cardiac Outflow Through the Cardioarterial Valve in the Lobster
Authors: Kuramoto Taketeru , Ebara Arinobu
Published: April 2021

Systolic pressure in the abdominal artery of the lobster Panulirus japonicus (Von Siebold) was decreased by contraction of the cardioarterial valve located at the posterior exit of the heart. Crustacean neurohormones, octopamine and proctolin, induced rhythmic contractions or contracture of the posterior valve but serotonin did not induce valve contracture. Systolic pressure in the posterior artery was reduced when the anterior cardioarterial valves contracted at the same time as the posterior valve. Proctolin caused the anterior and posterior valves to contract. Octopamine caused only the posterior valve to contract and often caused the anterior valves to relax. Proctolin induced depolarizing responses while serotonin often induced hyperpolarizing responses in muscle cells of the anterior and posterior valves. Octopamine hyperpolarized the resting membrane potential of muscle cells in the anterior valves and depolarized the membrane potential in the posterior valve. In some intracellular recordings from the valve muscle cells, slow action potentials followed by a plateau were produced on slow sustained depolarization induced by proctolin or octopamine. The action potential was followed by a large contraction of the valve. Contracture of the valve was associated with a large sustained depolarization in single muscle cells of the valve.
Hormonal control of muscle atrophy and degeneration in the moth Antheraea polyphemus
Authors: Schwartz L. M. , Truman J. W.
Published: April 2021

The intersegmental muscles of the giant silkmoth Antheraea polyphemus (Cramer) can undergo two forms of degenerative changes: a wasting atrophy that lasts about 6 days or rapid dissolution that is completed within 30 h. Muscle atrophy is induced by a dramatic decline in the endogenous titres of the steroid moulting hormone 20-hydroxyecdysone. 20-Hydroxyecdysone appears to act as a trophic factor for the muscles as infusion or injection of this steroid blocks further atrophy of the muscle. The normal decline of 20-hydroxyecdysone also allows the muscles to become competent to respond to the peptide eclosion hormone. Eclosion hormone is then released and acts directly on these muscles to induce rapid cell death which is morphologically and physiologically distinct from steroid-regulated atrophy.
Tracheal Gases, Respiratory Gas Exchange, Body Temperature and Flight in Some Tropical Cicadas
Authors: Bartholomew George A. , Barnhart M. Christopher
Published: April 2021

Fidicina mannifera Fab. (mass 3 g) can fly at a body temperature of 22 °C, but take-off is usually preceded by an endothermic warm-up that elevates Tth to 28 °C or higher. Warm-up is accompanied by slow, almost imperceptible, wing movements, gentle abdominal pumping and an increase in V·O2 to about 16 times the resting level. During wing-flapping in fixed flight, V·O2 increases explosively to about 70 times the resting level, and thoracic temperature rises to about 33 °C. Wing-beat frequency increases with Tth. Between 25 and 34 °C the mean wing-beat frequency is about 37 Hz. F. mannifera does not maintain free flight, or wing flapping in fixed flight, for more than about 100 s. Flight is supported aerobically, and we infer that exhaustion is related to depletion of substrate in the flight muscles.

The volume of the tracheal system of F. mannifera is about 45 % of total body volume. At rest, FO2 in the thoracic air sacs remains near 17 % and FCO2, near 3 %. During non-flapping warm-up, FO2 falls to as low as 1 % and FCO2 rises to as high as 21 %. Thus, gas exchange may limit the rate of warm-up. When wing-flapping commences, FO2 and FCO2 quickly return to near resting levels, presumably as a result of auto ventilation.

The interspecific regression of V·O2 on mass for three species of cicadas at 23-24°C has a slope of 0·89 and a 1-g intercept of 0·63 ml h−1.
A Movement Generated in the Peripheral Nervous System: Rhythmic Flexion by Autotomized Legs of the Stick Insect Cuniculina Impigra
Authors: Bässler U.
Published: April 2021

Autotomized legs of the stick insect Cuniculina impigra bend rapidly and rhythmically at the femur-tibia joint. These flexions occur at a frequency of 1–6 Hz immediately after autotomy and decrease in frequency and amplitude with time. Each flexion is produced by a burst of 1–14 action potentials in a single motor axon of the flexor tibiae muscle (bursting axon). These rhythmic discharges are generated in a very restricted part of the crural nerve, which contains the bursting axon, close to the autotomy point and appear whenever the nerve is cut in the immediate vicinity of this generator region. Rhythmic flexion can also be elicited by electrical stimulation of the crural nerve.

The bursting axon is of small diameter. It innervates all or most of the flexor tibiae muscle in which it produces relatively large EPSPs. Each EPSP elicits one muscle twitch. These fuse into a brief tetanus, whose amplitude is proportional to the number of spikes in a burst. Each tetanus produces one flexion.

This behaviour does not occur in the autotomized legs of several related species.
KCl Transport Across an Insect Epithelium: Characterization of K-Stimulated Cl Absorption and Active K Transport
Authors: Hanrahan J. W. , Phillips J. E.
Published: April 2021

The kinetics of 36C1 fluxes across cAMP-stimulated, short-circuited locust rectum were studied. Raising external K+ from 0 to 100 mM increased both Kt and Vmax for net Cl transport by four- to six-fold. Hill plots of indicated non-cooperative Cl interactions. The sequence for cation stimulation of was K > Rb > Cs > Na > NH4. Low levels of K were stimulatory only when added to the mucosal side. Cyclic AMP (cAMP) caused a small active absorption of K, although this was minor compared to the fourfold increase in transepithelial K diffusion (PK ). Neither cAMP stimulation of nor of PK was sensitive to Cl removal, suggesting that K-stimulated Cl absorption and K transport are not mediated by the same co-transport mechanism. Potassium is the counter-ion for electrogenic Cl transport because was less than 10% of the during cAMP exposure under Isc conditions, but equalled at open-circuit.
Electrolyte composition of parotid saliva from sodium-replete red kangaroos (Macropus rufus)
Authors: Beal A. M.
Published: April 2021

Saliva was collected from the parotid salivary gland of anaesthetized sodium-replete red kangaroos (Macropus rufus) by catheterization of the parotid duct through its opening in the mouth. Salivary secretion was stimulated by ipsilateral intracarotid infusion of acetylcholine at varying rates to produce salivary flow rates ranging from 0·056 ± 0·0042 (S.E. of mean) to 4·509 ± 0·1136 ml min−1. The concentrations of sodium (142·2± 1·93 to 157·0± l·17mmoll−1), calcium (40·1±7·08 to 72·8± 80μmoll−1) and bicarbonate (68·6±3·48 to 143·3 ± 0·67 mmol l−1) and the osmolality (270·1 ± 2·98 to 291·7 ± 2·10 mosmol kg−1) were positively correlated with salivary flow rate, whereas the concentrations of potassium (11·4±0·57 to 6·92± 0·19 mmol l−1), magnesium (206·0±34·1 to 9·3 ± 0·78μmol l−1), hydrogen ion (17·0± 1·89 to 6·82± 0·49 nmol l−1), chloride (30·7 ± 2·41 to 4·11± 0·23 mmol l−1) and phosphate (47·61± 2·65 to 14·9 ± 0·81 mmol l−1) were negatively correlated with flow rate. The relationships between flow rate and concentration were curvilinear for all the inorganic solutes. The rates of secretion for each ion and for total solute were positively correlated with salivary flow rate. These regressions for sodium, potassium, calcium, hydrogen ion, bicarbonate and osmolality were always linear, with highly significant correlation coefficients and variance ratios, which indicated that the changes in concentration of these ions were related solely to flow rate and were not due to any other factor modifying glandular function. Spontaneous secretion was’not observed during anaesthesia.
Stimulation of chemosensory pathways and intracellular alkalinization mimic cAMP activation of endogenous bursting in feeding command neurones
Authors: Gillette ML
Published: April 2021

Cyclic nucleotides modulate the activity of diverse types of excitable cells (Twarog & Muneoka, 1973; Berridge, 1975; Triestman & Levitan, 1976; Greengard, 1980; Bernier, Castellucci, Kandel & Schwartz, 1982; Gillette, Gillette & Davis, 1982b; Evans, 1984). In the carnivorous gastropod Pleurobranchaea, it would appear that cAMP modulation of a single pair of neurones effects the expression of a complex coordinated rhythmic behaviour. These neurones, the ventral white cells (VWCs), command vigorous motor output from the neuronal feeding oscillator through an intrinsic capacity to generate minutes-long high intensity bursts of action potentials (Gillette, Gillette & Davis, 1980). This high frequency firing causes the action potentials to increase in duration (broaden). The increase in action potential duration is a specific antecedent to enhanced motor output through a Ca2+-dependent mechanism (Gillette, Gillette & Davis, 1982a). Elevated intraneuronal cAMP is a specific activator of prolonged VWC bursting in both the isolated nervous system and the isolated VWC soma (Gillette et al. 1982b). The relationship between this endogenous effector (cAMP) and extrinsic activators of the motor programme has not been established.
Lithium attenuates the active transport of calcium in the larva of Aëdes aegypti
Authors: Barkai AI , Williams RW
Published: April 2021

Larvae of the freshwater mosquito Aëdes aegypti (L.) are able to maintain their principal electrolytes against a steep concentration gradient between the haemolymph and the external medium. The concentration of monovalent ions such as Na+, K+ and Cl- is kept far above that in the external medium by processes of active transport which are located in the anal papillae, the rectum and the Malpighian tubules (Koch, 1938; Ramsay, 1953; Treherne, 1954; Stobbart, 1959, 1960, 1965, 1967). Ithasbeen demonstrated that over 90 % of the exchange of monovalent ions occurs through the anal papillae (Treherne, 1954), but these organs are not permeable to bivalent ions (Wigglesworth, 1933). The processes which regulate the exchange of bivalent ions between the larva and the external medium have not yet been elucidated. Recently, we have demonstrated that larvae of Aëdes aegypti maintain a saturable transport system for the uptake of calcium ions from dilute calcium solutions (Barkai & Williams, 1983). This system obeyed Michaelis-Menten kinetics and its activity was susceptible to ruthenium-red which selectively inhibits Ca2+-activated ATPase (Watson, Vincenzi & Davis, 1971).
Effects of in vivo and in vitro changes in on the deformability of red blood cells of rainbow trout (Salmo gairdneri R.)
Authors: Hughes G. M. , Kikuchi Y.
Published: April 2021

Changes in haematocrit value are known to occur during hypoxia of rainbow trout and this has sometimes been interpreted as a result of an increase in red cell volume which is observed in vitro following equilibration with gas mixtures of low P02 (Black & Irving, 1938; Soivio, Westman & Nyholm, 1974). The possibility that there is also an increase in red cell number is still under discussion (Thomas & Hughes, 1982). The rise in blood haemoglobin content associated with such an increase would have physiological advantages for oxygen transport. However, an increase in haematocrit may increase resistance to blood flow and could impair the supply of oxygen at the tissue level. It is of interest, therefore, to know what are the effects of hypoxia both environmentally induced and under in vitro conditions on the flow properties of fish blood, for such effects have received little attention. This paper summarizes measurements of red cell deformability following changes from normoxic to hypoxic conditions, both in vivo and in vitro. A technique of filtration through a Nuclepore membrane has been used to provide an index of red cell deformability. During studies on yellowtail blood (Hughes, Kikuchi & Watari, 1982) variability in red cell deformability appeared to depend upon conditions of sampling and differences were observed in the filtration time of blood samples from normoxic and asphyxic fish. This effect has now been studied under more controlled conditions in rainbow trout.
A Cellular Mechanism of Classical Conditioning in Aplysia
Authors: Hawkins R. D.
Published: April 2021

The defensive siphon and gill withdrawal of Aplysia is a simple reflex, mediated by a well-defined neural circuit, that exhibits sensitization in response to strong stimulation of the tail. The siphon withdrawal reflex also exhibits classical conditioning when a weak stimulus to the siphon or mantle shelf (the conditioned stimulus or CS) is paired with a shock to the tail (the unconditioned stimulus or US). Cellular studies indicate that the mechanism of this conditioning shares aspects of the mechanism of sensitization of the reflex : presynaptic facilitation due to a cAMP-mediated decrease in K+ current and consequent broadening of action potentials in the sensory neurones. Thus, tail shock (the US) produces greater facilitation of the monosynaptic EPSP from a sensory to a motor neurone if the shock is immediately preceded by spike activity in the sensory neurone than if it occurs without spike activity (sensitization), or if the shock and spike activity are presented in a specifically unpaired pattern. This activity-dependent amplification of facilitation involves a greater broadening of action potentials in paired than in unpaired sensory neurones and appears to be due to a greater depression of the same serotonin- and cAMP-sensitive K+ current involved in sensitization.

These results indicate that a mechanism of classical conditioning of the withdrawal reflex is an elaboration of the mechanism underlying sensitization. By analogy, the mechanisms of higher-order features of learning, such as the effect of contingency, may be built from combinations of the molecular mechanisms of these simple forms of learning.
The Structural Basis of an Innate Behavioural Pattern
Authors: Wine Jeffrey J.
Published: April 2021

The abdominal nervous system of the crayfish contains six serially homologous ganglia, each containing approximately 650 neurones. No two ganglia are identical, and the ganglia interact extensively. Studies confined to intraganglionic interactions thus yield limited and sometimes misleading information. Each ganglion contains intrinsic (local) interneurones, motor neurones and projecting interneurones in roughly equal numbers, except in the specialized terminal ganglion where the ratio of these cells is approximately 3:2: 1. Although the number of nerve cell bodies in a ganglion is small enough to be tractable, integration occurs in the neuropile, which contains terminals from interneurones and afferents that outnumber the neurones originating in the ganglion by at least ten to one. The abdominal nervous system responds almost exclusively to a variety of mechanosensory stimuli. It has very limited light sensitivity. Other modalities, notably chemosensitivity, are undescribed and may be lacking. The effectors of the abdomen consist of fast axial muscles (used for tailflip-powered escape), slow axial muscles (for setting abdominal posture), appendage muscles (for swimmeret beating), and slow muscles of the intestine and rectum (that control gut emptying). The fast and slow muscles of the tailfan are specialized homologues of the axial and appendage muscles.

The abdominal nervous system represents only 3–4% of the 100000 neurones within the crayfish central nervous system (CNS). Most sensory information gathered in the abdomen is transmitted to the rostral CNS for processing, and many abdominal motor programmes are activated by descending commands. Nevertheless, a surprising degree of autonomy is present, and at least some motor programmes of every motor system can be activated in isolated abdomens.

Tailflip escape behaviour illustrates the integrative properties of the crayfish nervous system. Ninety pairs of efferents and eighteen pairs of interneurones have been identified within the abdominal portion of the escape circuit. A cell-by-cell analysis has so far provided neurophysiological explanations, in varying states of completeness, for ethological concepts such as innate releasing mechanisms, spatial patterning of movement, serial order in behaviour, and alterations in responsiveness to a constant stimulus.