bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies in Diurnal Rhythms I. Rhythmic Behaviour in Millipedes
Authors: Cloudsley-Thompson J. L.
Published: April 2021

Visual experiments on two small British species of millipedes have demonstrated that the diurnal cycle of rhythmic activity as represented by the number of animals on the surface is primarily a response to light and darkness, but is also correlated with the stimulus of falling temperature in the evening.

Aktograph experiments on two large West African species of millipedes have demonstrated an endogenous diurnal rhythm independent of fluctuating light and temperature, and persisting (in Ophistreptus) up to 19 days. Locomotory activity is stimulated both by increases and decreases of temperature; and it is probable that temperature fluctuations are of primary importance in the initiation of diurnal rhythms. The effect of light on activity is slight, but constant temperatures over long periods have, a depressing effect.
The Effect of Carbon Dioxide and Certain Respiratory Inhibitors on the Respiration of Larvae of the Horse Bot Fly (Gastrophilus Intestinalis De Geer)
Authors: Levenbook L.
Published: April 2021

In a previous paper (Levenbook, 1950a) it has been demonstrated that the larvae of the fly Gastrophilus intestinalis de Geer, parasitic in the stomach of the horse, contain far more carbon dioxide in their haemolymph and tissues than is normally found in insects, and that this is a consequence of the extremely high CO2 tension prevailing in their normal habitat. In the present study it will be shown that these larvae are so adapted to CO2 in their environment that its removal leads to a profound depression of their respiration and to eventual death.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A.
Published: April 2021

Evidence from osmotic experiments indicates that the amount of osmotically inactive material in the suctorian Podophrya is small, and that the internal osmotic pressure of the cytoplasm is approximately that of a 0·04 M solution of non-electrolyte. When the internal osmotic pressure of Podophrya is raised to an abnormally high level by equilibration with a solution of ethylene glycol or with dilute sea water, and the organism is then transferred to tap water, the rate of vacuolar output is temporarily raised far above its normal value. The body swells only slightly. This is taken as good evidence for osmoregulation. When Podophrya is placed in a dilute solution of sucrose the rate of vacuolar output (relative to the original rate in tap water) decreases rectilinearly with the concentration of sucrose used, reaching zero at about 0·04 M. This is as would be required for good osmoregulation. There is a slight lag in the response of the contractile vacuole to a change of medium. It is suggested that this delay in adjustment of the osmoregulatory mechanism must result in a slight change of body volume, which could be the basis for the control of vacuolar output.
Wave-Riding Dolphins*
Authors: Woodcock A. H. , Mcbride A. F.
Published: April 2021

In an effort to explain the apparent ability of dolphins to ride the bow wave of a ship at a speed of 10 knots (Woodcock, 1948) it seemed necessary to show that the animals had weight while immersed. Measurements of the weight of an immersed Stenella plagiodon have been made.‡ First results indicate that a dead animal, which weighs 200 lb. in air, and is 6·5 ft. long, weighs 9·2 lb. when immersed in sea water. This animal, which was in good physical condition, was killed by injection just before the weighings were made.
Aerodynamics of Flapping Flight With Application to Insects
Authors: Osborne M. F. M.
Published: April 2021

General formulae are derived giving the lift, thrust and power when the wing motion is specified. The formulae are applied to twenty-five insects for which quantitative data are available. Average values for lift and drag coefficients, CL and CD, are derived by equating the weight to the vertical force and the thrust to the horizontal drag of the body. The large drag and lift coefficients obtained for insect flight are attributed to acceleration effects. There is a distinct correlation between and the ratio of the flapping velocity of the wings to the linear velocity of flight. When this ratio and therefore the accelerations are small, the force coefficients do not exceed those to be expected for flat plates. Owing to the nature of the assumptions and approximations made, the values derived for CD, CL and CD/CL are minimum values. Other characteristics of insect flight are discussed. In general, insects fly in such a way as to minimize the mechanical power required. In most, but not all cases, the useful force is the one perpendicular rather than parallel to the relative wind. The wing tips should move in a figure 8, the down beat should be slower than the up beat, and the majority of the necessary force must be supplied on the down beat. Figures are given using the data from the twenty-five insects considered, showing average relations between power, specific power, mass, acceleration forces, force coefficients and geometrical dimensions. The power per gram, the ‘wasted power’, and the force coefficients all increase as the importance of the acceleration forces increases. When plotted as functions of mass, quantities involving the power show much less dispersion than quantities involving the geometrical dimensions. This is taken to mean that despite the diversity of insect form, as ‘power plants’, they are all essentially similar. A table of the observed or adopted flight parameters (frequency of beating, mass, wing area, velocity of flight, amplitude and orientation of wing motion) is appended.
The Reactions of the Minnow, Phoxinus Phoxinus (L.), to Solutions of Phenol, Ortho-Cresol and Para-Cresol
Authors: Jones J. R. Erichsen
Published: April 2021

This paper records some observations on the reactions of minnows to phenolic substances. The fish are placed in a horizontal tube, half of which is filled with flowing water and half with flowing solution of the concentration to be tested. Water and solution are very sharply differentiated.

Solutions of phenol, ortho- and para-cresol are highly toxic and appear to have some specific effect on the nervous system of fish, causing them to lose their sense of balance and capability of co-ordinated movement. The time the solutions take to produce this effect is much shorter than the survival time; in a 0.01% solution of para-cresol, for example, a minnow loses its sense of balance in about 70 sec. but takes about 30 min. to die.

Over the concentration range 0.04-0.0004% minnows appear to have little or no power of discriminating between phenol and water, swim into the solution and become intoxicated.

At concentrations of 0.03-0.04% minnows will avoid para-cresol and ortho-cresol solutions immediately and escape intoxication. At somewhat lower concentrations the fish venture into the solution, and this quickly destroys their capability of recognizing and avoiding it. The situation is markedly different from that observed in the case of lead and zinc salts; here the time the fish takes to establish an avoiding reaction to the solution is very much shorter than the time this takes to destroy its capability of doing so.
Cell Number in Haploid, Diploid and Polyploid Mouse Embryos
Authors: Beatty R. A. , Fischberg M.
Published: April 2021

Cell number, determined by counting the nuclei, has been studied in preimplantation haploid, diploid, triploid, tetrapioid and hexapioid eggs of Mus musculus, recovered usually days after fertilization. Most of the data concern triploid and tetrapioid eggs, from the early morula to late blastula stages. The mean number of cells in polyploid eggs (and perhaps in haploids), relative to the number in diploids of the same age, is approximately in inverse proportion to the number of chromosome sets present. Thus, the ratio of cell number in polyploid eggs to cell number in diploid eggs decreases with an increase in the number of chromosome sets. There was no evidence for any one type of heteroploidy that the différences in ratios encountered from mouse to mouse were due to anything other than sampling error, i.e. the ratios remained fairly constant from the early morula to the late blastula. This suggests that the lesser number of cells in polyploids is already apparent in early cleavage. These findings are compared with the parallel situation in Amphibia. The counting of nuclei can play a role, but only a limited one, in the identification of polyploid eggs.
The Influence of Water and Light Upon the Colour Change of Sightless Frogs (Rana Temporaria)
Authors: Rowlands Anne
Published: April 2021

Cauterization of the region of the optic chiasma causes the permanent expansion of the melanophores. Subsequent cauterization of the eye has no further effect. Severance of the optic nerve or damage to the eye itself results in the cessation of the chromatic response to illumination and background. Specimens operated upon in this manner do not lose the melanophore response to moisture, contracting in dry and expanding in moist conditions. Only a slight residual primary response can be detected. The implications of these results in relation to chromatic control are discussed.
Fermentation in the Rumen of the Sheep
Authors: Gray F. V. , Pilgrim A. F.
Published: April 2021

A previous communication in this series of papers (Gray, Pilgrim & Weller, 1951) gave an account of the fermentation of wheaten hay and lucerne hay by organisms from the rumen of the sheep, in which the overall production of each of the main volatile fatty acids was determined. In view of the complex nature of both the substrate and the mixed population of organisms involved, it was decided to investigate the intermediate stages of the fermentation to determine whether any important changes take place in the composition or in the rate of production of the mixture of acids.
The Swimbladder and the Vertical Movements of Teleostean Fishes
Authors: Jones F. R. Harden
Published: April 2021

Perch can only swim freely above their plane of equilibrium within a narrow zone whose height is equivalent to a 16% (one-sixth) reduction in the total pressure to which they are adapted. Excursions from this zone would not involve more than a 33 % reduction of the total pressure. Calculations were made of the minimum time in which perch could make slow vertical movements involving reductions of 10-90% in the total pressure to which they were originally adapted, and it was concluded that perch would not make diurnal migrations in which the reduction was more than 40% of the total pressure. It is unlikely that teleosts with closed swimbladders would be able to make diurnal migrations as extensive and rapid as that shown by the deep scattering layer unless the swimbladder was reduced in size, the bladder wall thickened to resist expansion of the gas, or the rate of gas resorption 20-30 times quicker than in the perch.
Pharmacological Investigation of the Nature of the Innervation of the Muscles of Helix Aspersa
Authors: Graham Jas. D. P. , Heathcote R. St A.
Published: April 2021

Bacq (1947) has reviewed the known actions of autonomic effector substances on invertebrates. Concerning the muscles of snails relatively little is known. Boyer (1926) showed that adrenaline had no effect on the contraction of the ventricular muscle of Helix pomatia in a concentration of less than 1 in 20,000, but that higher concentrations slowed the heart and produced irregularities of rhythm. Very high concentrations (1 in 250) arrested the heart beat. According to Jullien (1936) the ventricle of the same snail is sensitive to acetylcholine in a concentration of 1 part per million. There seems to be little other information available, other than the general statements of Bacq (1947) that in many Molluscs physostigmine (eserine) fails to potentiate the effects of acetylcholine, that in Cephalopods curare, but not atropine, abolishes the effect of stimulating the vesical nerve, and that in Molluscs as a whole the muscles of locomotion do not appear to be cholinergic in type.

In the common English snail, Helix aspersa, a portion of the alimentary canal (crop and rectum), or of the heart (ventricle), or the columellar muscle (which retracts the main part of the snail within its shell) was isolated, and the effects of drugs upon it examined, with the aim of determining the nature of the neurohormonal mechanism involved in contraction.
Studies on Tapeworm Physiology
Authors: Smyth J. D.
Published: April 2021

Plerocercoid larva of the cestode Schistocephalus solidus were cultured in vitro in horse serum + 1 % glucose at the following temperatures: 35, 34, 33 and 30° C. ; the temperature at which maturation normally takes place being 40° C. Eggs capable of embryonation were never produced by larvae cultured at a temperature less than 35° C. Below this temperature, spermatogenesis became markedly abnormal, resulting in the production of polyploid cells and degenerating spermatid morula. No abnormalities in the vitellaria or ovaries were observed at these subnormal temperatures.
The Action of the Proventriculus of the Worker Honeybee, APIS MELLIFERA L
Authors: Bailey L.
Published: April 2021

The proventriculus of the worker honeybee is an organ which effects a highly efficient separation of pollen grains from the medium in which they are suspended. The pollen grains are packed tightly together by the proventriculus and are passed as a bolus down to the ventriculus. The boluses pass quite quickly towards the posterior end of the ventriculus (5–20 min.), depending on the concentration and amount of pollen suspension which is fed. The peritrophic membranes do not move down the ventriculus with these packages but pass down at a slower rate. At the posterior end of the ventriculus the pollen may be held up for a considerable time. In the brood-rearing bee it stays there for many hours (up to 12 or more). In the forager it begins to pass down the hindgut to the rectum after 3 hr. or less. The volume of fluid within the honey stomach, the size of particles in suspension and their concentration have significant effects on the rate and efficiency of filtration by the proventriculus. Some reflexions are made on the possible physiological significance of the mechanism of the proventriculus to the worker honeybee.
The Relationship of Carbohydrate Metabolism and Mitotic Activity in the Mouse
Authors: Laws John O.
Published: April 2021

In recent years much interest has been shown in the biochemistry of mitosis, both as regards the process itself and the agents capable of controlling the frequency of its occurrence in the tissues. This interest has originated in two groups of workers, those biologists who are interested in the fundamental problems of growth and cell division, and the cancer workers who hope, by further understanding these processes, to be able to control the abnormal growth exhibited by tumours.
The Reactions of Fish to Water of Low Oxygen Concentration
Authors: Jones J. R. Erichsen
Published: April 2021

This paper presents the results of about 100 experiments to test the reactions of small fish to water of low oxygen concentration, using an apparatus similar to that previously employed by the writer to study the reactions of fish to toxic solutions. At 13 ° C. the stickleback (Gasterosteos acoleatos) has no immediate appreciation of water of low oxygen concentration and will swim into it with no hesitation. If the fish remains in the poorly oxygenated water respiratory distress develops, accompanied by uneasiness and random movement. When this random movement takes the animal back into the well-oxygenated water the stimulus to swimming vanishes, the fish stops moving and quickly recovers. Over a wide concentration range at 13 ° C. the reaction takes 1 · 3 min. At 3 ° C. the reaction is very slow, taking 5-6 min. even when the water contains only 0 · 3 mg./l. of oxygen. At 20 ° C. and oxygen concentrations below 2 mg./l. the response is very prompt, respiratory distress developing so quickly that the fish usually will not swim into the poorly oxygenated water, but turns away from it or swims backwards; it may make repeated attempts to enter the low-oxygen zone, retreating each time as if violently irritated. Experiments with minnows (Phoxinus phoxinus’) and trout fry (Salmo truttà) gave generally similar results. Here again the essential factor appears to be the speed with which dyspnoea develops.
The Metabolism of the Sea-Urchin Egg
Authors: Cleland K. W. , Rothschild Lord
Published: April 2021

The endogenous O2 uptake of sea-urchin egg homogenates (Echinus esculentus) was inhibited by malonate, fluoride, iodoacetate, and fluoracetate. The addition of the tricarboxylic acid cycle intermediates, citrate, a-keto-glutarate, succinate, fumarate, malate, and glutamate stimulated O2 uptake. The efficiency of the pyruvate-oxidizing mechanism varied in different preparations, but in some, added pyruvate was completely oxidized. (1)-(3) strongly suggest the presence of a tricarboxylic acid cycle. Glycogen, glucose and fructose stimulated O2 uptake. The oxidation of fructose was stimulated by DPN and inhibited by fluoride and iodoacetate. Glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate and fruc-tose-i :6 diphosphate stimulated O2 uptake. Phosphogluconate also stimulated O2 uptake, which suggests that the enzymes of the hexose monophosphate shunt system may be present. The experiments described in this paper show that the principal pathway by which carbohydrate is broken down is the normal glycolytic one.
The Fertilization Reaction in the Sea-Urchin
Authors: Rothschild Lord , Swann M. M.
Published: April 2021

The reactions of sea-urchin eggs (Psammechinus miliaris) to high concentrations of homologous spermatozoa have been investigated by a new method. The method was to inseminate eggs with high concentrations of spermatozoa (108/ml.), which ensured that all eggs were fertilized for the first time at the beginning of the experiment; and then functionally to separate the eggs and spermatozoa at known times after the original insemination. The proportion of polyspermie eggs in the suspension rises from zero at t = 0 to a constant value at a time T, which is the conduction time of the block to polyspermy. In fourteen experiments on eggs from different sea-urchins, the estimated values of T were 17, 69, 72, 74, 94, 85, 26, 60, 31, 91, 85, 34, 75 and 67 sec. (arithmetic mean 63 sec.). The standard errors of the estimates of T, which are tabulated in the text, ranged from 5 to 15 sec. These results confirm previous experiments which strongly suggested that the conduction time of the block to polyspermy was of the order of seconds; these earlier experiments were incompatible with a block to polyspermy lasting a fraction of a second. At the same time experiments in this paper made it possible to estimate the fertilization parameter or sperm-egg interaction rate a, during the conduction of the block to polyspermy, and to compare it with the pre-fertilization a. In a given sperm suspension, a is a measure of the receptivity of the egg surface to spermatozoa. During the conduction of the block to polyspermy a was found to be markedly lower (1/20) than in unfertilized eggs. This suggests that at fertilization there is a fast but incomplete block to polyspermy, whose conduction time may be 1 sec. or less. This is followed by the slower block which finally makes the egg impermeable to spermatozoa. This also confirms previous observations on the small incidence of polyspermy at normal sperm densities, which is not consistent with the concept of a slow block to polyspermy.
The Effect of Type of Contact with the Organizer on the Nature of the Resulting Induction
Authors: Waddington C. H. , Deuchar E. M.
Published: April 2021

The result of the activity of the primary organization centre in the amphibian gastrula is to determine a complex organized pattern of development. Within the ectoderm there arises a neural system in which, at the early stages, one can distinguish at least three different developmental types—brain, neural tube and neural crest ; another part of the animal hemisphere becomes mesoderm, and this can also be the result of an inductive action, since transplanted presumptive ectoderm can be caused to develop in this manner. There is general agreement that one cannot attribute these different end-results to any great extent to differences in the competence of the ectoderm submitted to the induction. There therefore remain two other factors to be investigated: differences either of a quantitative or qualitative nature within the organization centre, and differences in the type of contact between the various regions of the animal hemisphere and the organizer by which it becomes underlain. Waddington & Yao (1950) pointed out that there must be differences within the mesoderm in the rate at which evocating power is developed and in its final intensity, and they drew particular attention to the possible importance of the varying lengths of time during which the more anterior and the more posterior parts of the future neural system are in contact with inducing material.
The Random Element in Bird ‘Navigation’
Authors: Wilkinson D. H.
Published: April 2021

An analysis is presented of the results to be expected from experiments on the homing of wild birds if the only factor operating is random search. It is found that this model reproduces the experimental results and predicts values for the parameters involved in the theory which are inherently plausible and which are in quantitative accord with experimental evidence. Attention is paid to the dependence of percentage return on distance of release, to the dependence of the average speed of return on this distance, and to the distribution in time of the returns. These three sets of data form a coherent picture within the framework of the hypothesis of random search. Certain types of migration are also briefly considered.

It is not suggested that this investigation proves that random search is indeed the mechanism by which the homing of wild birds is accomplished, but it is submitted that the large-scale experiments of the type considered here are not susceptible of the interpretation that a true navigational ability is involved.
Further Developments on the Dynamics of Ovarian Hypertrophy
Authors: Lipschütz Alexander , Voss H. E. V.
Published: April 2021

It has been shown (Lipschütz, 1925) that the number of young ova in an hypertrophied ovarian fragment or in a fragment which has increased its volume by formation of cysts, is highly reduced as compared with a normal ovary. This phenomenon is of great significance for the understanding of the dynamics of ovarian hypertrophy. However this statement is not free from objections. If the diminution of young ova in such an ovarian fragment is really caused by the fact that a relatively greater number of young ova are used for follicular development, then there should be in certain cases an almost complete disappearance of young ova. Now there was only one case of a rabbit where this could be ascertained with surety (case B III.); but in this it was not known whether the fragments were not originally so small that the number of young ova was from the beginning a minimal one. As long as no case is available in which an almost complete disappearance of young ova in an increased ovarian fragment had been proved by counting the young ova in all the sections of that fragment, the objection is justified that the diminution of young ova is only an apparent one, the number of young ova originally present being now scattered in a greater volume. Moreover, the diminution of young ova might have been caused not by an increased follicular development but by some local conditions or by the operative interference.
Note On The Chromosomes Of The Genus Hypericum, With Special Reference to Chromosome Size in H. Calycinum
Authors: Chattaway M. M.
Published: April 2021

With the exception of four isolated papers published at different times since 1911, the large group of the Guttiferales had been undescribed from a cytological standpoint, until the appearance in the autumn of 1924, in Hereditas, of a paper by Niels Neilsen upon “Chromosome numbers in the genus Hypericum.”
The Effect of Gonadectomy on the Weight of the Kidney, Thymus, and Spleen of Mice
Authors: Masui Kiyoshi , Tamura Yasusige
Published: April 2021

There is a distinct sexual difference in the body weight of the mouse, the males being considerably heavier than the females. As the result of gonadectomy in the male there occurs no change in the body weight, while in the female it increases rapidly after spaying. A slight sexual difference is seen to exist in the body length, the females being longer than the males. Body length increases slightly after castration, while spaying produces no effect. There is a distinct sexual difference in the weight of the kidney, it being strikingly heavier in the male. The kidney of the castrated male becomes greatly reduced in weight and approaches that of the female kidney ; in the spayed female only a slight reduction in the weight of the kidney may be observed. The thymus of the female is considerably heavier than that of the male. As in the kidney, castration is followed by a striking increase in weight which approaches that of the female thymus ; spaying has but little effect. There is a distinct sexual difference in the weight of the spleen, it being considerably heavier in the female. The results of castration and of spaying are the same as in the case of the thymus. The results of the present study do not agree with Lipschütz’s hypothesis of an “asexual” type, for as the result of gonadectomy in the male the weight of the kidney, thymus, and spleen approaches that of these organs in the female, or, in other words, gonadectomy is followed by a development of the characters typical of the opposite sex.
Some Observations on the Dissociation of Hæmocyanin by the Colorimetric Method
Authors: Hogben Lancelot T.
Published: April 2021

By means of the colorimetric method the effect of temperature, hydrogen ion concentration, and salinity upon the dissociation of the hæmocyanin of four species of decapod crustacea (Maia, Cancer, Palinurus, and Homarus) has been studied. Rise in temperature depresses the dissociation curve continuously between 0° and 50° C. Reasons are given in favour of the conclusion that this behaviour is consonant with the applicability of the mass action law. On this understanding the heat of reaction between hæmocyanin and oxygen dissolved in the water phase in the case of Maia is of the order 9500 calories per n gram molecules of oxygen, n being defined as the least number of molecules of oxygen which can enter into the reaction. In the case of all four crustaceans referred to above, the affinity for oxygen diminishes up to a point as the hydrogen ion concentration is increased: on further increasing the hydrogen ion concentration beyond a critical value for which the affinity of the serum for oxygen is minimal, the amount of oxygen taken up at low tensions increases and may surpass the values obtained for serum at normal pH. The similarity of this result with the observations of Rona and Ÿllpo on hæmoglobin is discussed. On concentrating serum with neutral chlorides of the alakali and alkaline earth metals the dissociation curve is made steeper.
The Effects of Fat-Soluble Vitamin A Deficiency on Reproduction in the Rat
Authors: Parkes A. S. , Drummond J. C.
Published: April 2021

It is well known that vitamin A deficiency in the young animal checks growth and results in stunting for the period of the deficiency, Such animals, however, resume growth and reach the normal adult weight when put on to a complete diet. Animals in this dwarfed condition, weighing 70 to 90 gms. only at 3 to 5 months old, are quite sterile. Histological examination of the gonads and secondary organs, however, revealed in most cases no anatomical reason for their sterility. Gametogenesis was found to be in progress in these stunted animals, and the accessory organs appeared to be normal. It was concluded, therefore, that the sterility was due, primarily to physiological debility and disinclination to copulate. That this was actually the case was shown by a further batch of deficiency animals which were reciprocally mated with each other and with normals, daily examinations being made for evidence of copulation. None of the females copulated, but one only slightly deficient buck copulated with a normal doe. At the same time, however, vaginal smearing showed that the cyclic activity in the female genital organs, associated with the œstrous cycle, occurred in the deficient females. When normal weight is attained after recovery on natural diets breeding takes place freely, and fertility and sex-ratio show no marked abnormality.
On The Physiology of Amoeboid Movement
Authors: Pantin C. F. A.
Published: April 2021

Continuous amoeboid movement is essentially a rhythmic phenomenon (Pantin, 1924), to some extent comparable with rhythmic contraction in muscle. Yet no complete investigation of the action of ions has been made which enables this unspecialised contractile mechanism to be compared with heart-muscle and cilia. The subject is important because in unicellular organisms the state of the cell can be observed simultaneously with the movement; it can also be seen at once if all the cells react in the same way. In muscle only indirect evidence can be obtained on these points.

Marine amoebae are peculiarly suitable for this work, because the composition of sea-water is accurately known and an artificial medium therefore prepared with comparative ease. Quantitative results are obtained by selecting a species of the limax type and measuring the rate of movement.
On The Physiology of Amoeboid Movement
Authors: Pantin C. F. A.
Published: April 2021

The previous paper of this series (Pantin, 1926) described the action of certain ions upon a species of marine amoeba, and especially the relation of calcium to amoeboid movement. The same paper detailed the method of preparing isotonic salt solutions and of determining their effect on amoeboid movement. The essential feature is that the average velocity is taken as a measure of the effect of a solution upon the power of movement, apart from other effects produced upon the cell. Unless otherwise stated, the CH of the solutions was maintained at pH 7.0 to 7.2.
Simultaneous Determination of Sodium and Potassium in Small Volumes of Fluid by Flame Photometry
Authors: Ramsay J. A. , Brown R. H. J. , Falloon S. W. H. W.
Published: April 2021

A method of flame photometry is described, by which the amount of sodium and potassium in biological fluids can be determined simultaneously, using samples of the order of 10−3 cu.mm. When the method is tested with quantities near the lower limits of detection (of the order 4 × 10−8 mg. sodium, 6 × 10−8 mg. potassium) the reproducibility, measured as standard deviation, is ±7 × 10−9 mg. sodium and ± 17 × 10−9 mg. potassium. When larger quantities (up to certain limits) are used, the standard deviation is approximately ± 3 % of the quantity in the sample, both for sodium and for potassium. As is usual in flame photometry serious errors can be caused by the presence of other substances in the sample. In the case studied for purposes of illustration it is shown that these interference errors can be reduced to the order of ± 6 % by the addition of excess ammonium phosphate.
The Fertilization Reaction in the Sea-Urchin
Authors: Rothschild Lord
Published: April 2021

Treatment of unfertilized sea-urchin eggs with sea water containing nicotine is known to induce polyspermy when the eggs are subsequently inseminated with homologous spermatozoa, at densities which cause a very small amount of polyspermy in untreated eggs. If nicotine were to increase the speeds at which sea-urchin spermatozoa swim, the chances of fertilization, and therefore of polyspermy, might be increased. Nicotine does not increase sperm speeds; in addition, it causes a sharp reduction in the O2 uptake of these spermatozoa. The only other ways in which nicotine could induce polyspermy are by altering the egg surface in such a way that the probability of fertilization is increased by a factor of about twenty; or by lengthening the conduction time of the block to polyspermy. Experiments described in this paper show that the first explanation is untenable and therefore that the second is the correct one. It is concluded that nicotine abolishes the fast incomplete block to polyspermy and that over-exposure to this substance probably abolishes the block to polyspermy altogether. Polyspermic eggs divide sooner than monospermic ones. When, as in these experiments, eggs are allowed to interact with spermatozoa for known times, and then functionally separated by immersion in hypotonic sea water, some eggs, presumably those which sustain a successful sperm-egg collision at the end of the interaction time, are activated but not fertilized by the spermatozoon, as in the pseudogamous nematodes. Cleavage does not occur though the egg nucleus swells. Previous results in the same field and observations by other workers are discussed.
The Flight of Birds
Authors: Brown R. H. J.
Published: April 2021

In a previous paper (Brown, 1948), the movements of the wing of a pigeon in slow flight were analysed. With the help of a new photographic technique further work on the flight movements at different forward velocities has been carried out. In this paper the analysis is extended with additional information obtained from normal cine-photography. Certain improvements and simplifications in the flash cinematographic methods are also described.
The Gregarious Behaviour of MarchingLocusta Migratoria Migratorioides(R. & F.) Hoppers
Authors: Ellis Peggy E.
Published: April 2021

The amount of marching by 4th-instar hoppers of Locusta migratoria migratorioides (R. & F.) which have been reared in crowds, was studied in relation to the total number of individuals and to the size of the cage. Below 50 hoppers per cage, marching depended partly on the total number of hoppers present and partly on the number in relation to the area of the cage floor. Above 50 hoppers per cage, marching probably depended on the total number present, rather than the area of the cage floor. In all cages, marching was greatly reduced with fewer than 30 hoppers, although even single individuals marched for part of the time. An investigation of the hopper interactions which lead to an increase in marching activity in groups showed that the two most important were visual and mechanical ones. Test hoppers followed moving hopper bodies alive or dead, but only gave a partial response to moving vertical stripes. Mechanical interactions between hoppers greatly increased the proportion of reacting hoppers, but did not increase the distance travelled by the active individuals, beyond those travelled in response to optical stimuli alone. Maximal marching activity, by the maximal proportion of hoppers in a band, depended on an opto-motor response to a moving background of hopper shapes and to the physical contact between hoppers. Air and floor vibrations from other marching hoppers played only a small part in marching, whilst stimuli received via the antennae tended to inhibit marching when total activity was low. The importance of the experimental results in explaining the behaviour of locust hoppers in the field was discussed.
Sun Navigation in Homing Pigeons
Authors: Matthews G. V. T.
Published: April 2021

The accumulated data of a long series of homing experiments carried out with young pigeons is examined in statistical detail. Bico-ordinate navigation can only be demonstrated in sunny conditions, and with overcast skies the birds scatter at random. This holds for a number of different experimental situations. The hypothesis that pigeons use a form of sun-navigation, deriving latitude and longitude from the sun position alone is re-examined in detail. None of the requirements are outside the theoretical range of the organ concerned, or beyond the bounds of possibility. Examination of the errors made under sunny conditions shows that their nature and variation are as expected on the basis of the hypothesis. So also is the variation in error with the length of time of observation. By excluding sun and sky for a number of days before release a re-orientation away from home was obtained. This could only be explained if the birds were failing to correct for the seasonal variation in the sun’s altitude, and deriving their latitude from altitude measurements. Radical changes in accustomed release times produced some increase in longitude errors. After treatment aimed at desynchronizing any internal chronometer a disorientation was obtained in the field. It is therefore very probable that longitude determination is on a time basis, as proposed in the hypothesis. Future lines of research in this problem are indicated.
The Orientation of Untrained Pigeons: a Dichotomy in the Homing Process
Authors: Matthews G. V. T.
Published: April 2021

It is demonstrated that young pigeons without any previous training show a definite homeward orientation at a distance, yet home very badly. The results are compared with those of birds with varying amounts of training. An essential dichotomy in the homing process is revealed, between the orientation process which is innate and the process of return which is governed by factors developed by individual experience. The further contrast between the unitary nature of the orientation process and the multiplicity of factors concerned in the return is supported by statistical consideration of the individual variation in ability. The practical and theoretical implications of these conclusions are considered.
Navigation in the Manx Shearwater
Authors: Matthews G. V. T.
Published: April 2021

Homing experiments were carried out with 338 Manx Shearwaters from Skokholm Bird Observatory, Pembrokeshire. The especial advantages of this species for such work are described. With sunny conditions, strong homeward orientation was shown by birds released at points unknown to them. Early in the season these releases gave very fast, complete returns, more than half back on the first 2 nights. Those on the first night were unequivocal evidence of long, direct flights over unknown country. One shearwater homed at least 3050 miles across the Atlantic in 1212 days. There was a decline in the proportion of returns later in the season, probably due to a loss of stamina. With conditions of heavy cloud the homeward orientation broke down and returns were poorer. The stage of the individual incubation shift has some effect on the homing performance. For the first time we have a demonstration of complete evidence for navigational ability in a wild bird. The suggestion of a form of sun navigation is in line with evidence obtained with pigeons and gulls. The failure of workers with other species to produce such evidence is not considered to weigh against the possibility of navigational ability of this kind in all proven homers. The sun-navigation hypothesis is investigated. Although shearwaters fly to the burrows after dark they are unable to navigate after sundown. Determination of the latitude from the sun’s altitude can only be tested in this species by trans-equatorial experiments. Determination of longitude by time differences was tested by attempting to desynchronize the necessary internal ‘chronometers’. The first attempt was in-conclusive owing to cloudy conditions at release. A second attempt was also partially thwarted by the weather, but gave suggestive results favouring the hypothesis. More experiments of this nature are required. An analysis of the range of shearwaters from the colony, based on banding results, is given. The Wilkinson flight-duration recorder was used on this species, but did not give satisfactory results.
Studies on the Mesogloea of Coelenterates
Authors: Chapman Garth
Published: April 2021

The physical properties of the isolated mesogloea of Calliactis and Metridium are described and the behaviour of the tissue on loading recorded. It can be compared with a spring and dashpot model. It is shown that the viscous-elastic properties of the body-wall, which have previously been ascribed to the muscles, are the attributes of the mesogloea. On being heated in water under a small load, isolated mesogloea of Calliactis contracts, at temperatures which are only a little higher than those at which vertebrate collagen contracts. This is regarded as additional evidence for the collagenous nature of the mesogloea protein. It is shown that the physical behaviour of the material is consonant with the crossed fibrillar collagenous nature of the mesogloea described elsewhere.
Oxygen Consumption and Cell Size. A Comparison of the Rate of Oxygen Consumption of Diploid and Triploid Prepupae ofDrosophila MelanogasterMeigen
Authors: Ellenby C.
Published: April 2021

The oxygen consumption and surface area of individual diploid and triploid prepupae of Drosophila melanogaster have been measured, the cells of triploid animals being larger. The mean weights for the types examined are different but their ranges overlap almost completely. By covariance analysis it is shown that, after adjustment for difference in body size, there are no differences in the rates of oxygen consumption. It is concluded that, for these animals, cell size has no influence on the rate of oxygen consumption. The relationships between body weight, surface area, and oxygen consumption have been further investigated. It is shown that, despite the greater inaccuracy of the method by which surface area is determined, oxygen consumption can be predicted more accurately from surface area than from body weight. The results are discussed in relation to an earlier investigation of the oxygen consumption of other genotypes (Ellenby, 1945 a, b). Possible technical causes of certain differences between the two series of results in the relationship of oxygen consumption and body weight are explored ; it is concluded, however, that they are almost certainly due to differences, not necessarily genetical, between the animals used in the two series.
Metabolism of the Black Snake Embryo
Authors: Clark Hugh
Published: April 2021

Bohr (1904) reported CO2 production of an embryo of Natrix natrix, weighing 0·46 g., to be 120 mm.3/g./hr. at 14·2° C.; the CO2 produced at 28° C. was 3 times that at 15° C., and production by a newly hatched snake at 15° C. was approximately 90 mm.3/g./hr. Other data are given, but they are not related to stage of development, and oxygen utilization was not measured. Zarrow & Pomerat (1937) made rather exhaustive studies of the effect of temperature on various aspects of respiratory behaviour of the smooth green snake during the last week of development. It appeared profitable, therefore, to obtain details of respiratory exchange throughout the developmental period of snake embryos. Such data were available from the same embryos which served for the excretion studies reported elsewhere in this Journal by the author (1953).
Cleavage of Sea-Urchin Eggs in Colchicine
Authors: Swann M. M. , Mitchison J. M.
Published: April 2021

Sea-urchin eggs have been treated with strong colchicine during mitosis, and examined with a variety of techniques. Polarized light observations show that cleavage can take place when the asters and spindle have completely disappeared, provided the cell has reached mid-anaphase, by which time the chromosome groups are well separated. Observations on stained sections have confirmed those with polarized light and have also shown that the minimum separation of the chromosome groups for successful cleavage is about 5 μ. Viscosity measurements have shown that colchicine destroys the gelated structure of the asters, and reduces the viscosity of the cleaving egg to about the same low value as the unfertilized egg. Cycles of chromosome condensation persist in eggs treated with weak colchicine, even though cleavage has been prevented by an early application of the colchicine. These cycles are associated with changes in the rigidity and light-scattering properties of the cortex. The relevance of these observations to some theories of cell division is discussed.
Microdissection Experiments on Sea-Urchin Eggs At Cleavage
Authors: Mitchison J. M.
Published: April 2021

Chambers (1938) described an experiment in which he cut open one blasto-mere of a cleaving sea-urchin egg at the dumb-bell stage in isotonic KCl. The other blastomere contracted like a ‘deflating balloon’, and this has been taken by other workers as evidence of a positive membrane tension in the cleaving egg. This experiment has been repeated with other sea urchins in various media. It is concluded that this effect only takes place in one species of sea urchin, in an abnormal medium, and after it has suffered irreparable damage. It is not, therefore, legitimate to suppose that there is normally a positive membrane tension in a cleaving egg. It is found that eggs will continue to cleave with one blastomere in an irregular shape which indicates that, on the contrary, there is no membrane tension and no internal pressure. These are the conditions demanded by the ‘expanding membrane’ theory of cleavage. It is found that the furrow of a cleaving egg will pass through a needle placed in its path. This result argues against a simple contracting ring in the furrow region being responsible for cleavage. Chambers (1938) found that an egg will continue to cleave when its asters have been destroyed by stirring. This result has been confirmed by a similar experiment on a different species of sea urchin. This is crucial evidence against an astral mechanism of cleavage. The effects of compressing cleaving eggs have been studied. It is found that compressed eggs continue to cleave unless the degree of flattening is considerable; that cleavage is delayed before it is finally stopped; and that eggs in Ca-free sea water are more susceptible to compression than eggs in ordinary sea water. These results are consistent with the ‘expanding membrane’ theory.
The Moulting Fluid of the Cecropia Silkworm
Authors: Passonneau Janet Vivian , Williams Carroll M.
Published: April 2021

The initiation of adult development in the pupa of the Cecropia silkworm is accompanied by a retraction of the hypodermis from the pupal cuticle; the exuvial space is simultaneously flooded with the moulting fluid. During the first two-thirds of adult development the moulting fluid is a dilute, aqueous, proteinaceous gel resembling egg albumen ; at this time it is without effects on the pupal cuticle. On approximately the fourteenth day of adult development the gel is converted into a sol and shows a considerable increase in chitinase activity and the first demonstrable proteolytic activity. The late, active moulting fluid then begins to hydrolyse the protein and chitin in the overlying pupal endocuticle. By the twentieth day the old endocuticle has disappeared. The tanned proteinchitin complex of the sclerotized exocuticle is not attacked. Finally, the moulting fluid is completely resorbed into the underlying insect. The residual pupal exocuticle forms the bulk of the exuviae. Moulting fluid and blood are compared in respect to the following properties : consistency, cellular content, solubility, refractive index, water content, chemical composition, total nitrogen, protein nitrogen, pH, redox potential, and enzymatic content. The moulting fluid shows numerous quantitative and qualitative differences from the blood. The fluid is, evidently, a distinctive secretory product of the underlying integument—presumably of the hypodermis itself. A dynamic state exists between the moulting fluid and the underlying insect. Radioactive glycine, injected into the moulting fluid, was promptly resorbed and incorporated into the protein of the adult moth. Several lines of evidence suggest that the secretion or activation of the moulting fluid enzymes are synchronized with the sclerotization of the underlying new cuticle. This synchronization, it is suggested, may serve to protect the new cuticle from the hydrolytic action of the moulting fluid.