bluuebunny/crossref_metadata_2025 huggingface dataset:
Wallerian Degeneration in the Rat
Authors: Mannell W. A. , Rossiter R. J.
Published: April 2021

If a peripheral nerve is cut, that portion of the nerve distal to the point of section undergoes a series of changes characteristic of Wallerian degeneration. Logan, Mannell & Rossiter (1952 a) showed that in the peripheral segment of the sciatic nerve of the cat degenerating after nerve section there is an increase in the concentration of nucleic acid. This change, which is probably related to the cellular proliferation that accompanies Wallerian degeneration, involves both pentosenucleic acid (PNA) and deoxypentosenucleic acid (DNA), although the increase in the two nucleic acids is disproportionate, resulting in an increase in the PNA/DNA ratio. Johnson, McNabb & Rossiter (1949 a) and Brante (1949) showed that there is also a later decrease in the concentration of myelin lipid, related to the destruction of the myelin sheath. Mannell (1952) reported similar changes for the sciatic nerve of the rat, although in this species all the processes are considerably speeded up in time.
The Respiratory and Glycolytic Enzymes of Sea-Urchin Eggs
Authors: Yčas Martynas
Published: April 2021

A number of workers have studied the carbohydrate metabolism of sea-urchin eggs and have expressed different opinions about the pathway of carbohydrate breakdown in these eggs. The choice has rested between the breakdown of hexose via the ‘hexose monophosphate shunt’ and a glycolytic mechanism like that in yeast and muscle, followed by oxidation via the tricarboxylic acid cycle. Rothschild (1951) has summarized the evidence on this question. In listing the evidence in favour of the latter view, Rothschild included work reported in the author’s Ph.D. thesis (Yčas, 1950). Some of these results are presented in this paper. The evidence for a normal glycolytic and respiratory system has since been greatly extended by Cleland & Rothschild (1952a, b).
On The Drinking of Soil Capillary Water by Spiders
Authors: Parry D. A.
Published: April 2021

A study has been made of the drinking of soil moisture by two species of lycosid spider. Carborundum powders have been used to provide a ‘soil’ of uniform particle size. The rate of drinking falls off with increase in the suction applied to the capillary water, finally becoming negligible, even though the soil remains saturated, at a suction which varies with the species of spider and possibly with the size of the individual. This limiting suction is never reached if the capillaries empty at a lower suction. The rate of drinking does not fall off with time, is similar for different individuals of the same species and size, and is not affected by soil particle size at a given suction, provided this is below the critical suction for the soil.
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord , Tyler A.
Published: April 2021

The effect of adding sea water containing different concentrations of versene to suspensions of sea-urchin spermatozoa (Echinus esculentus) has been investigated, as regards their respiration, motility and fertilizing capacity. The respiratory Dilution Effect is progressively reduced and finally abolished when, instead of sea water, sea water containing 10−6, 10−5, 10−1 or 10−3 M versene is added to sperm suspensions. At the same time versene greatly delays the senescence of the spermatozoa, both as regards their motility and fertilizing capacity. For example, after seventeen hours, a 106 sperm/ml. suspension in sea water containing 10−3 M versene has 125 times the fertilizing capacity of a suspension containing 107 sperm/ml. without versene. The change in the ratio of seminal plasma to sea water which occurs when a dense suspension is diluted does not explain the Dilution Effect. These results are discussed in relation to the hypothesis which accounts for the Dilution Effect in terms of trace metals, particularly copper, normally occurring in sea water, and the amounts available per spermatozoon under various conditions of dilution.
A Physiological Interpretation of the Marching of Hoppers of the African Migratory Locust (Locusta Migratoria Migratorioides R. & F.)
Authors: Ellis Peggy E. , Hoyle G.
Published: April 2021

Hoppers of the locust Locusta migratoria migratorioides R. & F., which have been reared crowded, exhibit characteristic marching behaviour in the laboratory in foodless cages under standard conditions. The rate of attainment of maximum marching by a given group of hoppers is greatest following a short period of starvation immediately preceding transfer to these conditions. A meal of filter-paper soaked in sugar solution only, exerts no retarding effectA physiological interpretation of marching hoppers 279 on the rate of attainment of full marching, whilst if an adequate concentration of potassium salt is added in addition a definite retardation is observed. In locusts actively feeding on grass the potassium content of the blood is relatively high, and it is suggested that this causes a reduced muscular efficiency which may explain retardation in attainment of full marching. The marching pattern is the result of the activity of particular nerve centres which require a period of activation by a combination of factors before full expression is achieved. Two final factors are essential for the maintenance of the marching state, a low concentration of blood potassium and mutual stimulation by other marching hoppers.
Observations on the Mechanism of the Opening of the Valves of A Burrowing Lamellibranch, Mya Arenaria
Authors: Trueman E. R.
Published: April 2021

The ligament of Mya arenaria allows the valves to open normally and permits a rocking movement of the valves about a dorso-ventral axis to take place. This movement, which makes burrowing possible, is also associated with the divarication of the posterior end of the shell to allow the withdrawal of the siphon. A method of determining the resistance of various marine soils, ranging from clean sand to offshore mud, to the opening of the valves of M. arenaria is described. Even in the offshore mud, which is much less resistant than the sand, the opening moment of the ligament is approximately 6 times too small to cause the valves to gape. Records have been made of the opening of the valves of M. arenaria when loaded experimentally to varying degrees. A closing pattern of activity was observed with loads applied not exceeding the opening moment of the ligament, and with greater loads an opening pattern. The opening of the valves, in the latter instance, is found to be associated with a sudden increase in the water pressure in the mantle cavity. The increase in pressure is shown to be of the correct order of magnitude to open the valves of Mya in muddy sand by the application of a steady force. The liquefaction of the sand surrounding the lamellibranch, possibly by the expulsion of water through the pedal opening, would greatly facilitate the opening of the valves.
Fourth (Final) Report on A Test of McDougall’s Lamarckian Experiment on the Training of Rats
Authors: Agar W. E. , Drummond F. H. , Tiegs O. W. , Gunson M. M.
Published: April 2021

This is the final report of an experiment of 20 years’ duration, in which we have repeated, in its essentials, the well-known experiment of William McDougall purporting to reveal a Lamarckian inheritance of the effects of training on rats. The test is one involving light discrimination, and McDougall recorded a steady improvement in the rate of learning on a succession of 32 generations; but he omitted to check the results against a properly conducted control.

Our experiment confirms McDougall to the extent that we too have obtained long duration trends of improvement in learning-rate (Figs. 2, 3); but we find that the effect is not sustained, and that it is, moreover, shown also by a control experiment, using animals of untrained ancestry. This forbids a Lamarckian interpretation.

Statistical analysis of the data indicates that the ‘condition’ of the rat markedly affects its speed of learning, and that progressive changes in learning-rate, over a succession of generations, are in reality correlated with the health of the laboratory colony, which is subject to periods of decline and recovery.
Water Balance in the Tick Ornithodoros Moubata Murray, with Particular Reference to the Influence of Carbon Dioxide on the Uptake and Loss of Water
Authors: Browning T. O.
Published: April 2021

A study has been made of the exchanges of water between the atmosphere and the tick Ornithodoros moubata. Unfed nymphs are able to abstract water from moist air (95% R.H.) and to restrict their rate of water loss in dry air. This ability is lost (a) in atmospheres containing 30-45% CO2; (b) in atmospheres containing more than 90% N2 (c) immediately after the tick is fed; (d) gradually after the tick has been starved for some five months. It has been shown that the effect of high (30-45%) concentrations of CO2 is mainly upon the activity of the epidermal cells, possibly mediated through the central nervous system. The concentration required to cause opening of the spiracles is only about 5%.
Osmotic Responses in The Sipunculid Dendrostomum Zostericolum
Authors: Gross Warren J.
Published: April 2021

The sipunculid Dendrostomum zostericolum demonstrates no ability to regulate osmotically. Dendrostomum behaves superficially as an osmometer, but is actually more complex: (a) the worm shows volume control in concentrated and dilute sea water; (b) it is permeable to salts, mostly through the gut and/or nephridiopores; (c) it can release osmotically active particles from its body wall to the blood. The body wall of Dendrostomum is highly permeable to water, but only slightly to salts. Permeability for both salts and water is greater inwards than outward. Dendrostomum can tolerate a loss of 36% body weight by desiccation and recover when returned to sea water. The mechanism of this tolerance appears to be the removal by fixation in the tissues, of osmotically active particles from the body fluids.
The Colour Change of the Minnow (Phoxinus Laevis Ag.)
Authors: Healey E. G.
Published: April 2021

Minnows were subjected to spinal section at different levels between vertebrae 4 and 15, and the degree of dispersion of all the main melanophore regions was recorded in terms of the melanophore index. Records were made of the times required to reach equilibrium (a) when the fish were placed after the operation on a black or white illuminated background, and (b) when the fish at equilibrium on a black or white background were subjected to background reversal. These records show that the times necessary for the melanophores to reach equilibrium on a given background are of the same order at all the vertebral levels investigated. There is considerable variation in the degree of dispersion of similar melanophore regions of different individuals under the same conditions of operation and background. The nature of these individual differences is not known. Apart from the possibility of incomplete section of chromatic nerve fibres near the 15th vertebra, there appears to be no correlation between the chromatic behaviour and the level of the operation ; i.e. there is no indication that any activity of the spinal paling centre is being affected by spinal section at the different levels. The results of experiments involving the elimination of the spinal paling centre were tested statistically. Within the limits of this treatment, based upon the melanophore index, it was concluded that the spinal paling centre plays no part in these colour changes. Spinal section was carried out anterior to the 1st spinal nerve in order to interrupt the path of von Gelei’s dispersing fibres. Statistical treatment of the results indicates that these fibres are playing no part in these colour changes. Experiments involving combined spinal and autonomic section confirm the conclusions given in paragraphs 6 and 7. Since no activity of the nervous system arising from the spinal paling centre or resulting from the background through von Gelei’s dispersing fibres appears to be involved, the colour changes of these spinal minnows in response to illuminated backgrounds must be controlled by hormones alone. In these spinal fish the various melanophore regions do not all react equally in terms of the melanophore index. Thus, those of the lateral stripe and associated dark pattern tend to have relatively higher M.I. values under all conditions.
Structure and Function in the Locomotory System of the Dogfish Embryo. the Myogenic Stage of Movement
Authors: Harris J. E. , Whiting H. P.
Published: April 2021

A brief description is given of some features in the special morphological organization of the neuromuscular system in the embryo of the lower vertebrates. The development of locomotory behaviour patterns in elasmobranchs is compared with that in other groups. The earliest movements of the embryo of Scyliorhimis caniculus have been photographically recorded ; the results of Wintrebert are confirmed. The movements persist unchanged after complete removal of the nervous system ; they are rhythmical and independent on the two sides. Any isolated portion of an actively contracting myotome band can act as its own pace-maker. The histological structure of the nerve cord and muscle at the time of these first movements is described in detail. There is strong evidence against any morphological link between the motor neurons and the myotome band; other neurons in the developing spinal reflex arc are similarly unconnected with one another. The results are discussed in relation to similar phenomena in other systems. Consideration is given to the mechanism of the excitation and transmission of the contractile process in the myotome band.
The Rate of Urine Production of Anodonta Cygnea
Authors: Potts W. T. W.
Published: April 2021

The inulin clearance rate of a too g. Anodonta varies from about 0-2 ml./hr. at o° C. to 10 ml./hr. at 180 C. The rate of urine production, inferred from the initial rate of loss of weight in an isotonic solution, is 1-9 ± 11 ml./hr. at 15o C., and is thus of the same order as the inulin clearance rate.
Experiments on the Light Sense of the Hag, Myxine Glutinosa L
Authors: Steven D. M.
Published: April 2021

The response of the hag to light consists of one or more local movements followed after a further interval by general locomotory activity. The first local movement has been used as a measure of the reaction time. The reaction time is inversely proportional to the intensity of the stimulus at illuminations less than about 10 e.f.c. At higher levels of illumination it attains a constant minimum value. Hags respond to intensities at least as low as 0·1 e.f.c. but only after several minutes illumination. Estimates of the penetration of light through sea water suggest that the hag’s light sense is of functional value. The spectral sensitivity maximum lies between 500 and 520 m μ. Hags are virtually insensitive to wave-lengths longer than about 600 m μ. The significance of the spectral sensitivity is discussed in relation to the spectral transmission of sea water and the evolution of photosensitive systems.
On The Reaction to Light of Myxine Glutinosa L
Authors: Newth D. R. , Ross D. M.
Published: April 2021

That the effectively eyeless hag, Myxine glutinosa, is responsive to light was reported by Gustafson (1935). Our own interest was aroused by the behaviour of some hags (kindly sent to us by Dr Gustafson) which were being photographed. A tank containing a number of them was brightly illuminated for a few seconds only. Some 20 sec. later the animals, which had previously lain motionless in the semi-darkness, started, rather suddenly, to swim. The long delay between stimulus and response seemed to merit study while the definiteness of the response promised an important help to observation. The present paper reports the behaviour of hags under different conditions of illumination and a preliminary investigation of the sensory physiology of their responses.
The Excretion and Storage of Ammonia by the Aquatic Larva of Sialis Lutaria (Neuroptera)
Authors: Staddon B. W.
Published: April 2021

A study has been made of the excretion and storage of ammonia by the aquatic larva of Sialis lutaria. About 90 % of the nitrogen excreted by the larva of Sialis during starvation was in the form of ammonia. The daily ammonia output averaged 10 μg. N/100 mg. wet weight. Ammonia was found to be excreted into the hindgut, presumably via the Malpighian tubules. The concentration of ammonia in the hindgut fluid averaged 136 mg. N/100 ml. Evidence was obtained that the tissue fluids are not maintained completely ammonia-free. Thus the total ammonia content of the body averaged 1·0 μg. N/100 mg. wet weight of tissue. The concentration of ammonia in the haemolymph averaged 0·50 mg. N/100 ml. Evidence was obtained that the larval tissues are capable of ‘storing’ appreciable quantities of ammonia. Thus ammonia did not accumulate in the tissue fluids of larvae prevented from excreting for a period of 5 days. Furthermore, it was found experimentally possible to raise the concentration of ammonia in the tissue fluids, the ammonia subsequently disappearing. The possible significance of this ‘storage’ mechanism was discussed. The method used for raising the concentration of ammonia in the tissue fluids, by immersing the larva for some time in a solution of dilute ammonia, was considered in some detail, particularly with respect to toxic effects. When the concentration of ammonia in the haemolymph had reached a level in the region of 7·0 mg. N/100 ml. toxic symptoms started to appear.
The Functions of the Ocelli of Calliphora (Diptera) and Locusta (Orthoptera)
Authors: Cornwell P. B.
Published: April 2021

By determining the appropriate physical constants of the ocellus it is shown that in both Calliphora and Locusta the focal plane lies much deeper than the retinal space so that the eye cannot perceive form with any accuracy. The large visual fields afforded by their position on the head and the position and shape of their retinae suggest that the ocelli are efficient light-gathering units. The ocelli alone are unable to mediate phototactic responses to light of the intensities employed in these experiments. The efficiency of phototactic reactions mediated by the compound eyes is, under certain conditions, significantly greater when the ocelli are intact than when they are occluded. In Calliphora this stimulatory influence of the ocelli is not manifest at a low light intensity. In Locusta nymphs, ocellar occlusion produces an effect only when the compound eyes are light-adapted and orientation depends on light stimulating the anterior part of the eye. In both species, the experimentally observed behaviour is explicable on the theory that ocellar occlusion causes a decrease in the sensitivity to light of the anterior part of the compound eye.
Urine Production by the Antennal Glands of Palaemonetes Varians (Leach)
Authors: Parry Gwyneth
Published: April 2021

Four methods for estimating the rate of urine flow in Palaemonetes varions are described. The rate is minimal when the external medium is approximately isotonic with the blood. All methods indicate that the rate increases progressively with increasing dilution of the external medium below 50 % sea water. There is some evidence to suggest that the rate increases in hypertonic external media. These results are discussed in relation to estimates of the urine production in some other Crustacea and in relation to the ecology of the genus Palaemonetes.
Inhibitors of Tyrosinase
Authors: Pryor M. G. M.
Published: April 2021

It has been reported that if Drosophila larvae are ground to a fine paste with sand, the homogenate shows little tyrosinase activity, but that if the larvae are allowed to blacken in chloroform vapour before grinding, activity is increased. This has been interpreted as showing the effect of an intracellular inhibitor, set free by rupturing the cells, but destroyed by chloroform. This inhibitor has been identified by previous authors as a dehydrogenase. It is here suggested that the lack of activity of Drosophila extracts prepared with sand is due to destruction of tyrosinase as it oxidizes naturally occurring aromatic substrates. It is shown that tyrosinase is destroyed by oxidizing the aromatic substrate present in the cuticle of Calliphora larvae, or by very low concentrations of homocatechol. The aromatic substrate of Calliphora larvae is concentrated in the cuticle, and would be set free by fine grinding. Drosophila or Calliphora larvae yield a more active extract when ground with sand than when simply crushed, provided that they are tested soon after grinding. The tyrosinase activity of such extracts is not increased by chloroform or methanol. The compound between o-quinones and amino-acids is capable of oxidizing ascorbic acid or excess amino-acid without the aid of an enzyme, and of simultaneously reducing methylene blue. This reaction, rather than the activity of dehydrogenases, is probably responsible for most of the ability of damaged insect tissue to bleach methylene blue. The blood of insects normally contains dissolved oxygen in equilibrium with the air. The reaction involved in the blackening of insect blood may consume all the dissolved oxygen. Previous observations on fluctuations in the oxidation-reduction potential of the blood of Calliphora larvae with age are probably due to changes in the rate at which oxygen is consumed by the blood after it is shed. There does not therefore appear to be any valid evidence that tyrosinase is inhibited in vivo by the action of dehydrogenases. The absence of tyrosinase activity in undamaged tissue is probably due to the structure of the cytoplasm, which keeps enzyme and substrate apart. Instances of the inhibition of tyrosinase reported in Crustacea and Echino-dermata seem to be susceptible of the same explanation as in insects. The supposed inhibitory effect of sulphydryl groups reported for vertebrate melanophores is shown to be due to the combination of sulphydryl groups with o-quinones, which prevents the formation of melanins.
Membrane Potentials in the Muscles of the South American Frog, Leptodactylus Ocelatus
Authors: Harris E. J. , Martins-Ferreira H.
Published: April 2021

The experiments described here were made in Brazil during 1953. Their primary purpose was to explore the properties of the muscle fibres of the locally available frog, Leptodactylus ocelatus, and to find out whether, in spite of the very different climate to which the animals are accustomed, their isolated muscles provide as convenient experimental preparations, and give similar results to those obtained, for instance, with the sartorius of European Rana temporaria. This was found to be the case, and in addition to repeating a number of established effects on Leptodactylus ocelatus, some new results obtained with changes in the ionic composition of the solution will be reported. Intracellular recording of resting and action potentials was used and the conditions were chosen so that the experiments could be compared with those made by other authors. In addition, an investigation of the effect of some of the variables upon the rate of extrusion of sodium from the muscle fibres was measured by radioactive tracer methods ; these results will be reported later.
The Movement of Sea-Urchin Spermatozoa
Authors: Gray J.
Published: April 2021

Although the mechanical activity of spermatozoa plays an essential role in the process of fertilization there is little precise information concerning the type and speed of movement of individual cells in their normal state of activity. This paper represents an attempt to fill this gap with respect to a sea-urchin whose spermatozoa, being of the typical monoflagellate type, provide valuable material for the study of flagellar propulsion in general.
The Propulsion of Sea-Urchin Spermatozoa
Authors: Gray J. , Hancock G. J.
Published: April 2021

The movement of any short length of the tail of a spermatozoon of Psammechinus miliaris and the characteristic changes which it undergoes during each cycle of its displacement through the water can be described in terms of the form and speed of propagation of the bending waves which travel along the tail (Gray, 1953, 1955); the form of the wave depends on the maximum extent of bending reached by each element and on the difference in phase between adjacent elements. The object of this paper is to consider the forces exerted on the tail as it moves relative to the surrounding medium and to relate the propulsive speed of the whole spermatozoon to the form and speed of propagation of the bending waves generated by the tail. The mathematical theory of the propulsive properties of thin undulating filaments has recently been considered by Taylor (1951, 1952) and by Hancock (1953); the present study utilizes and extends their findings but approaches the problem from a somewhat different angle. resistance, and consequently the transverse displacement (Vy) elicits reactions tangential and normal to the surface of the element. The latter force (δNy) has a component(δNysinθ) acting forward along the axis (xx ′) of propulsion; it is this component which counteracts the retarding effect of all the forces acting tangentially to the surface.
Electrometric Titration of Chloride in Small Volumes
Authors: Ramsay J. A. , Brown R. H. J. , Croghan P. C.
Published: April 2021

The potentiometric end-point in the titration of chloride with silver nitrate depends upon the fact that the concentration of Cl- ions determines the potential of a silver wire coated with silver chloride which dips into the titration vessel. This chloride electrode is connected through a voltmeter with a reference electrode which completes the circuit, and when the end-point is reached there is a very rapid change of potential between the electrodes, of the order of 100 mV or more. This method is not only convenient but also promises to be practicable on the micro-scale where there is insufficient thickness of solution for the colour change of an indicator to be perceptible.
The Sensitivity of the Pedal Ganglion of the Slug to Osmotic Pressure Changes
Authors: Kerkut G. A. , Taylor B. J. R.
Published: April 2021

The effects of different dilutions of Locke solution on the electrical activity of the isolated pedal ganglion of the slug can be reproduced by adding different concentrations of glucose or mannitol to a given concentration of Locke. This indicates that certain cells in the pedal ganglion are sensitive to the osmotic pressure of the solution and not its ionic concentration. The preparation is sensitive to slow changes in the concentration of the bathing medium. The cells increased their activity when the bathing solution was slowly changed from 0-7 Locke to o-6 Locke, the change taking 43 min. This corresponds approximately to a change of 1 % of the body fluid concentration over 4 min. Such rates of change are found in the normal intact animal. The sensitivity of the preparation compares well with that of the mammalian osmoreceptors.
Biochemical and Physiological Studies of the Purified Toxin of Walterinnesia Aegyptea ‘The Egyptian Black Snake’
Authors: Mohamed A. H. , Zaky O.
Published: April 2021

Two methods for preparation of the toxin in a purified crystalline form are described. The toxin is probably a secondary proteose. It has an excitatory parasympathetic effect on the uterus of the guinea-pig and on the intestine of the rabbit. The effect is abolished by atropine. It causes excessive salivary secretion, again abolished by atropine. It causes partial or complete block of perfused isolated amphibian and mammalian hearts. It also causes extrasystoles. Both effects are abolished by atropine. The minimum lethal dose for rats is 0·035−0·05 mg. toxin/100 g. body weight. Atropine did not save the life of the animal although it prolonged it. The possibility of a histamine-like action of the venom is discussed.
The Role of the Symbiotic Bacteria in the Nutrition of Rhodnius Prolixus (Hemiptera)
Authors: Baines S.
Published: April 2021

Earlier views of the nature of the association between Rhodnius and its symbiotic bacteria are confirmed. The bacterium is described as Nocardia rhodnii in accordance with more recent views of the classification of the Gram-positive filamentous bacteria. Experimental evidence is provided to show that the symbiotic bacterium is essential to Rhodnius because of its function in supplying certain B group vitamins, in which the normal blood diet of the host is deficient.
Sun Navigation of Apis Mellifica L. in the Southern Hemisphere
Authors: Kalmus H.
Published: April 2021

The sun navigation of honey bees has been investigated in a region of the southern hemisphere where the sun was moving counter-clockwise during the observations.

Foragers from a strain long established in the region were fed in the evening on a dish in a particular geographical direction and transferred overnight to a new locality unknown to them. During the next day the majority of bees were at all hours searching in the direction of their previous training.

Foragers which were the offspring of queens recently imported in an inseminated state from the northern hemisphere showed after similar training systematically false orientation on the day of observation. The direction of their search shifted by about 30° per hour counter-clockwise from a direction about 90° clockwise from the training direction in the morning to the correct direction in the evening.

Bees of hybrid (local and imported) origin also showed false orientation.

The existence of innate mechanisms is postulated compensating in northern bees for the sun’s clockwise movements and in southern bees for the counterclockwise movement of the sun. The change in the direction of compensation must have occurred during the last 425 years, and a possible mode of this evolutionary process is discussed.
Factors Which Influence the Acquisition of Flagella by the Amoeba, Naegleria Gruberi
Authors: Willmer E. N.
Published: April 2021

When placed in distilled water Naegleria gruberi changes from an amoeboid organism, with little evidence of polarity, to a highly polarized free-swimming flagellate. The details of this metamorphosis are described. The change is reversible. Alteration of osmotic pressure is not in itself the direct cause of the metamorphosis, though the loss of certain ions is clearly important. The metamorphosis is favoured by the presence of low concentrations (less than M/8O) of sodium bicarbonate, sodium lactate and sodium phosphate. The flagellate form probably occurs most frequently in conditions of neutrality ; but, in the presence of phosphate, acid conditions tend to be more favourable to the flagellate form, while in the presence of bicarbonate the optimum pH is nearer pH 8 0. The metamorphosis to the flagellate form is suppressed by a variety of agents including lithium salts, magnesium chloride and the sulphate ion under some conditions. These all act at concentrations which leave the amoeboid form in full activity. In some cases their action is decreased by the presence of bicarbonate in the medium.
Respiration in the African Swampworm Alma Emini Mich
Authors: Beadle L. C.
Published: April 2021

Alma emini, a glossoscolecid oligochaet, is a common inhabitant of the waterlogged and often floating mat of decomposing vegetable matter which forms the substratum of the papyrus swamps of East Africa. Oxidation-reduction potential (E7) measurements in the field show that to within a fraction of a centimetre of the surface this material is strongly reducing and is presumably devoid of free oxygen. Alma lives with most of its body immersed in this material, but for much of the time it exposes to the air a tubular ‘lung ‘formed by the upfolding of the edges of the highly vascular dorsal surface at the hind-end. On retreating from the surface bubbles of air are often carried down enclosed in this tube. The dissociation curve of the haemoglobin is such as might well fit the animal to this mode of life. In the absence of CO2 it is saturated at about 2 mm. Hg of oxygen. A Bohr effect is not detectable unless the tension of CO2 is raised to about 200 mm. Hg, and even then it is slight. This would also fit it for respiration in a medium in which very high tensions of CO2 must occur.. In the laboratory it is unaffected by prolonged exposure to an atmosphere of pure CO2. Though apparently capable in the laboratory of a purely anaerobic metabolism, its behaviour in mud-water cultures suggests that it needs oxygen for survival in its normal environment. The possible functions of aerobic and anaerobic respiration are discussed.
Quick and Slow Contractions in the Isolated Sphincter of the Sea Anemone, Calliactis Parasitica
Authors: Ross D. M.
Published: April 2021

There are two kinds of neuromuscular activity in sea anemones that are full of interest for the comparative physiologist: (1) the conspicuous quick withdrawal movements which can be elicited by any strong stimulus; (2) the almost imperceptible and continuous slow changes of shape and position, incorporated in various feeding and pumping activities, which may be elicited by general or local stimulation of moderate intensity.
The Function of the Brain of Octopus in Tactile Discrimination
Authors: Wells M. J. , Wells J.
Published: April 2021

The results of fifty-three experiments in which octopuses were trained to make tactile discriminations between the members of pairs of Perspex cylinders are reported. Grooves cut into these otherwise smooth cylinders varied in number and arrangement. The proportion of errors made in distinguishing such objects depends upon the difference between the proportions of groove on the objects concerned, and is not affected by the pattern or orientation of the grooves. It has thus been possible to measure the similarity to Octopus of the objects used and to predict the errors that will be made in any such discrimination.

When these results are considered in the light of the known nervous arrangements in the arms, it is possible to present a hypothesis about the mode of action of the peripheral tactile sensory system and the function of the brain. It is necessary to suppose that the latter distinguishes frequencies of nerve impulses in the sensory nerves from the arms; it is not necessary to postulate any projection of the sensory field or scanning mechanism involving the use of proprioceptive information.
Effect of Phosphate and Chloride Ions on Aerobic Metabolism of Bovine Spermatozoa
Authors: Salisbury G. W. , Nakabayashi N. T.
Published: April 2021

Under the aerobic conditions of these experiments, dilution of bovine semen with phosphate ion depressed oxygen consumption and motility of sperm cells. However, fructose utilization and lactic acid accumulation were increased in the presence of phosphate ion. When semen was diluted with isotonic sodium chloride oxygen uptake was greater, motility was maintained better and fructose utilization and lactic acid accumulation were lower than in the phosphate-diluted semen.

Twice-washed cells in a diluent containing seminal plasma utilized more fructose and accumulated more lactic acid than those in plasma-free diluent. The depressive effect of phosphate on respiration was not due to H2O2 formation nor to changes of osmotic pressure.

The season of the year in which semen was collected influenced its metabolic response in each of the diluents studied. The presence of glucose-6-phosphate dehydrogenase activity was not conclusively demonstrated in cell-free extracts of bovine spermatozoa prepared by sonic oscillation.
Oxygen Consumption As a Function of Size and Salinity in Metapenaeus Monoceros Fab. from Marine and Brackish-Water Environments
Authors: Rao Kandula Pampapathi
Published: April 2021

The oxygen consumption in relation to the salinity of the medium has been studied in a marine and a brackish-water population of the prawn, Metapenaeus monoceros Fab. It has been shown that the regression coefficient of oxygen consumption against weight is not the same for media of different salinity and for the two populations. In both the groups of prawns an increase in the oxygen consumption was observed, with a decrease in the salinity of the medium below that of the habitat. But the marine prawns showed higher rates in 50 and 25 % sea water compared to the brackish-water prawns. On the other hand, the brackish-water prawns exhibited a higher rate of oxygen consumption in 100% sea water and in tap water. It is suggested that these differences might be due to (i) an osmotic adaptation, and (ii) the operation of a metabolic homoeostatic mechanism in relation to osmotic regulation.
Surface Characters of Dividing Cells
Authors: Ishizaka Shozo
Published: April 2021

The surface movements during division have been studied by marking the naked surface of the sea-urchin egg with charcoal particles. The contours of the largest optical section, the positions of the particles thereon and the positions of the astral centres are recorded in a series of camera lucida drawings. The drawings are then superimposed, the centre of gravity and spindle axis being used for reference. It is thereby shown that there are two surface rings which remain in the same positions throughout the whole process of division. It is concluded that these rings indicate regions where stresses remain balanced during division.
On ‘The Stationary Surface Ring’ in Heart-Shaped Cleavage
Authors: Dan Katsuma
Published: April 2021

In the foregoing paper, Ishizaka (1958) succeeded in demonstrating the presence of a pair of ring-zones in the cortex of sea-urchin eggs which remain absolutely stationary with reference to the co-ordinates outside the egg through successive changes of the form of dividing ova. The purpose of the present paper is to see whether or not a similar situation exists in the case of cells cleaving in a heart shape ; i.e. in cells in which the cleavage furrow of one side appears earlier than that of the opposite side.
Osmotic and Ionic Regulation in Scottish Brown Trout and Sea Trout (Salmo Trutta L.)
Authors: Gordon Malcolm S.
Published: April 2021

Adult brown trout (Salmo trutta L.) of both sea-run (sea trout) and freshwater stream (brown trout) forms were captured in the vicinity of Aberdeen and acclimatized to full-strength sea water for periods of up to 5 months. Blood serum samples from these fish were analysed for freezing-point depression, chloride, sodium and potassium concentrations. The patterns of regulation of these concentrations are very nearly the same in both forms. Brown trout and sea trout, at least in eastern Scotland, thus appear to be virtually identical in osmotic and ionic regulatory abilities. However, there is a possibility that there is a difference between the two forms with respect to mechanisms controlling blood acid-base balance. The patterns of regulation shown by Scottish fish are the same as those shown by American hatchery fish treated similarly. The different populations of the species seem not to have diverged significantly from one another in this regard after many generations of more or less complete genetic isolation. The species Salmo trutta is strongly homoiosmotic. Internal concentrations are either unchanged or increase by less than 10% above fresh-water levels with long-term acclimatizations to half and full sea water. The brown trout is the first salmonid species known to regulate so well.
Superpregnancy in the Mouse
Authors: McLaren Anne , Michie Donald
Published: April 2021

Weight increase of female mice during pregnancy was studied in normal pregnancies, and also in females of various ages in which superovulation and mating had been induced by gonadotrophin treatment. In some spontaneous and induced pregnancies, the weights of the gravid uterus and of the live embryos were taken at autopsy 1812 days post coitum in addition to the total weight of the intact pregnant female. The main weight increase in both treated and control pregnancies occurred between about 1012 and 1612days post coitum. The weight gain per embryo showed a linear decrease with increasing numbers of embryos, and a linear increase with the 712-day weight of the female. When the data were adjusted to a standard 712-day maternal weight, the total weight gain at first rose with embryo number, but declined when the number of embryos increased above the normal range. The extra-uterine weight increase of the female declined with increasing numbers of embryos. We conclude that female mice carrying abnormally large numbers of embryos economized not only on embryonic growth but also on extra-uterine weight increase. Young mice carrying large litters appeared to use up a large proportion of their fat reserves during pregnancy.
The Physical Properties of the Swimbladder in Intact Cypriniformes
Authors: Alexander R. McN.
Published: April 2021

A method is described whereby certain physical properties of the swimbladder have been determined in intact, unoperated Cypriniformes. These properties are volume, excess internal pressure, extensibility, and relative sensitivity (an index of the rate of change of volume with depth). The mean volume of the swimbladder varies in the twelve species examined from 5.8 to 9.9 ml./100 g. body weight. In most Cyprinidae the swimbladder gases are maintained at a mean pressure 2-3 cm. Hg above that of the surrounding water at the depth to which the fish is adapted. Higher pressures occur in a few species, most notably the bream (10.8 cm. Hg). A much lower pressure is found in Amiurus. An excess internal pressure is probably necessary to provide a taut swimbladder wall to operate Weberian ossicles. The swimbladder wall has non-linear elastic properties such that as the excess pressure in the swimbladder rises the extensibility of its wall falls. The swimbladder also shows slow-elastic properties. The significance of these properties is discussed. Excess internal pressure and low extensibility combine to limit the rate at which the volume of the swimbladder, and so the buoyancy of the fish, changes with depth. For small depth changes the swimbladder of the bream (an extreme case) changes its volume only one-quarter as much as would a free air-bubble.
The Densities of Cyprinidae
Authors: Alexander R. McN.
Published: April 2021

The mean sinking factor of each of eight species of Cypriniformes has been determined by a method involving measurement of the pressure at which anaesthetized specimens float. It was found to lie between 1001 and 1004 for all species except the gudgeon, for which it is 1008. Roach, dace and carp have swimbladdere of very different sizes. It was shown that differences in the weight and density of the skeleton and scales, and in muscle density, are important factors in determining the volume of swimbladder gas necessary for neutral buoyancy. Differences in fat content are unimportant in these fish.
The Physical Properties of the Isolated Swimbladder in Cyprinidae
Authors: Alexander R. McN.
Published: April 2021

The anterior sac of the cyprinid swimbladder is much more extensible than the posterior sac. The anterior sac is not significantly more extensible in length than in other directions.
Some Observations on Tick Paralysis in Marmots
Authors: Emmons Patricia , Mclennan H.
Published: April 2021

Infestation with certain species of ticks gives rise in a number of animals to a paralysis which if unrelieved may end in death. The effect of such parasites is felt particularly in the ranching areas of South Africa and along the east coast of Australia, where sheep and dogs respectively are principally affected, and in cattle ranches west of the Rocky Mountains in Canada and the north-western United States. In this last area the condition is produced by the bite of the ixodid tick Dermacentor andersoni Stiles (Gregson, 1953).
The Shadow Reaction of Diadema Antillarum Philippi
Authors: Millott N. , Yoshida M.
Published: April 2021

Light is shown to suppress the shadow reactions of Diadema spines to a degree which varies with its intensity. Inhibition can occur when there is spatial separation between the areas shaded and illuminated in the radial nerve and skin. The degree of inhibition is affected by the position and size of the area lighted. In both skin and radial nerves, uniform meridional gradients of inhibition are found, inhibition being maximal when the areas lighted and shaded are near or coincide, decreasing as these areas are moved apart. The effect of light may be reversed when it is projected at more than a critical distance from the shadow. Gradients in the skin which run parallel to the ambitus, show maximal inhibition at the ambulacral margins, so that the inhibitory gradient corresponds with that of sensitivity to shadows. Interaction between excitation and inhibition may occur in the radial nerve or at the periphery and there are several pathways for excitation and inhibition. The findings are discussed in relation to ‘off’ effects and receptor fields in retinae.
The Shadow Reaction of Diadema Antillarum Philippi
Authors: Yoshida M. , Millott N.
Published: April 2021

Our previous account of the spectral sensitivity (Millott & Yoshida, 1957) was based on a study of the spine response in isolated pieces of test bearing many spines. The areas illuminated and shaded extended over the whole internal or external surface.
The Response of the Ampullae of Lorenzini of Elasmobranchs to Mechanical Stimulation
Authors: Murray R. W.
Published: April 2021

The ampullae of Lorenzini are sensitive to weak tactile stimulation applied to the ends of their jelly-filled tubes. Either an increase or a decrease in their resting discharge frequency may be caused, each with an opposite after-effect. ‘Adaptation’ is total, being three-quarters completed in 3-8 sec. This ‘adaptation’ probably includes accommodative changes of the tissues. The function of the ampullae is discussed, but no definite conclusion can yet be reached.
Some Factors Affecting the Oxygen Consumption of Asellus
Authors: Edwards R. W. , Learner M. A.
Published: April 2021

The oxygen-consumption rates of Asellus aquaticus (males and females) have been measured at 10 and 20° C. using a constant-volume respirometer, and the effect of starvation for 24 hr. investigated. The oxygen consumption is approximately proportional to the 0.7 power of the wet weight. The rate of oxygen consumption at 20° C. is greater than at 10° C. by a factor of 1-5. The oxygen-consumption rates of A. aquaticus and A. meridianus have been measured at 20° C. in a flowing-water respirometer employing a polarographic technique for the measurement of dissolved-oxygen concentrations. The oxygen consumptions of A. aquaticus and A. meridianus are similar and decrease by 15-20% when the dissolved-oxygen concentration falls from 8.3 to 1.5 p.p.m. The oxygen consumption of A. aquaticus is between 35 and 75 % higher in the polarographic respirometer than in the constant-volume respirometer.