bluuebunny/crossref_metadata_2025 huggingface dataset:
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord
Published: April 2021

Spermatozoa and seminal plasma of Echinus esculentus contain catalase. At 15° C., 4 ml. of a suspension of semen diluted with neutral phosphate buffer in the ratio 1:13 produced in 1 min. 90 μl. O2 from an H2O2 solution containing 150 μl. O2. The dry weight of semen in the suspension was 45 mg. and the number of spermatozoa 8·55 × 10−9. Under the same conditions, seminal plasma obtained by centrifuging semen produced 50 μl. O2 in 1 min. The dry weight of seminal plasma in the suspension was 12 mg. Human blood, dry weight 229·3 mg./ml., must be diluted with phosphate buffer in the ratio 1:1700 to produce the same amount of O2 in 1 min. as the above suspension of semen. If catalatic activity is defined by the equation Ae= (gt)−1 In {a/(a—x)}, where g = weight in g./ml. of the catalase-containing material, t=i min., a = initial substrate concentration (H2O2), and x = amount of H2O2 decomposed in 1 min. at 15° C., Ac= 80–100, 150–200 and 6800 respectively for sea-urchin semen, sea-urchin seminal plasma and human blood. The catalatic activity of semen and seminal plasma is strongly inhibited by hydroxylamine. The 02 uptake and motility of sea-urchin spermatozoa is unaffected by M/5000 H2O2. Higher concentrations of H2O2, M/3000·5000, produce a pronounced ‘shock’ effect, from which the spermatozoa often completely recover. Low concentrations of hydroxylamine, M/3000, reduce O2 uptake and motility. Sea-urchin spermatozoa are almost instantly killed by combinations of hydroxylamine and H2O2, at concentrations which are relatively innocuous when the substances are added separately. A rough calculation indicates that a single spermatozoon contains less than 500 molecules of catalase. A new method of adding H2O2 to catalase-containing material in a manometer is described.
A Note on the Catalase Content of Sea-Urchin Eggs
Authors: Rothschild Lord
Published: April 2021

During experiments on the catalase content of sea-urchin spermatozoa, opportunities arose of measuring the catalatic activity of sea-urchin eggs. Fertilized and unfertilized eggs of Echinus esculentus were examined, the jelly having been removed in each case. Holter & Linderstrom-Lang (1936) and Holter (1937) investigated the catalase content of sea-urchin eggs, but they were particularly concerned with the location of this enzyme in the cell. The catalatic activity of sea-urchin eggs has attracted attention on several occasions in the past (see, for example, Kobert, 1903), but the results were unquantitative and sometimes contradictory. Furthermore, no workers examined the effect of low concentrations of hydroxylamine on the apparent catalatic activity of these cells. Hydroxylamine is a specific inhibitor of catalase as opposed to other substances which catalytically decompose H2O2 into O2 and H2O.
The Role of the Coelomic Fluid in the Movements of Earthworms
Authors: Newell G. E.
Published: April 2021

A short review is given of the coelom and of its morphological relations in the earthworm. The arrangement of the intrinsic muscles in a typical septum is described. Four main sets of muscles are recognized: viz. radial muscles, circular muscles, oblique muscles, and the sphincter around the ventral foramen. It is suggested that the function of the radial, circular and possibly of the oblique muscles is to control bulging of the septa, and so serve to localize differences in pressure in the coelomic fluid. Normally, in active worms, the sphincter of the ventral foramen is contracted and forms an effective barrier to the passage of fluid from one coelomic compartment to the next. This was verified experimentally and by X-ray photography. A series of measurements of the pressure in the coelomic fluid in different regions of active worms was recorded by means of a capillary manometer and by the use of a spoon-gauge apparatus. Manometric measurements showed the average pressure in the anterior third of the body to be 16.0 cm. water and in the tail region to be 8.0 cm. water. The corresponding figures obtained with a spoon gauge were 13.5 and 8.5 cm. water. The pressure in narcotized worms is zero. These results are discussed, and it is pointed out that the manometer readings suffer from the disadvantage of failing to show the rapid fluctuations in pressure which occur during wriggling movements of the worms. It is calculated from these pressure readings that a worm can exert a forward thrust equivalent to forces of between 1.5 and 8.0 g. These figures agree well with those obtained by Gray & Lissman by the use of a special torsion balance. The burrowing movements of earthworms are briefly described. It is shown that the sphincters of the dorsal pores and of the nephridiopores do not normally allow of the escape of coelomic fluid, and will withstand a pressure well outside the normal range.
The Electrical and Mechanical Events of Neuro-Muscular Transmission in the Cockroach, Periplaneta Americana (L.)*
Authors: Roeder Kenneth D. , Weiant Elizabeth A.
Published: April 2021

Though the mechanical activity of insect muscle has been studied by many workers (notably Heidermanns, 1931 ; Solf, 1931 ; Kraemer, 1932; Cremer, 1935), and insect-muscle potentials have been recorded by Rijlant (1932) and Pringle (1939), no attempt has been made to examine the precise relation between motor-nerve impulse, muscle potential, and muscle contraction in this group. The purpose of this account is to examine the electrical and mechanical signs of neuro-muscular events in the cockroach, and to evaluate them in the light of current concepts of neuro-muscular transmission in Crustacea and invertebrates.
Of the Movement of Worms
Authors: Chapman Garth
Published: April 2021

Four aspects of the functioning of a fluid-filled cylindrical animal have been examined, viz.: (I) the role of the body fluid as a skeleton for the interaction of the longitudinal and circular muscles of which the animal must be composed; (2) the measurement of the maximum thrust which the animal can exert by measurement of its internal hydrostatic pressure; (3) the application of the force to the substratum and the part played by friction; (4) the relation between the changes in dimensions of the animal and the working length of the muscles.

Under (1) the necessity for a longitudinal and circular construction has been shown and the necessity for a closed system emphasized.

Under (2) the pressure exerted on the body fluid by the contraction of the longitudinal and circular muscles is discussed, and from their cross-sectional areas it is shown to be probable that when contracting maximally in Lumbricus they are not balanced, but that the longitudinals are about ten times as strong as the circulars.

Under (3) it is shown that the strength of an animal as measured by its internal hydrostatic pressure is sufficient to account for its customary activities. Use which may be made of the longitudinals during burrowing is pointed out.

Under (4) it is shown to be mechanically sound for burrowing animals of cylindrical form to be ‘fat’, but that a ‘thin’ animal is more efficient at progression.
The Effect of Pituitrin Injection on the Water Balance of Bufo Regularis Reuss
Authors: Ewer R. F.
Published: April 2021

A method of cannulating the cloaca of Anura is described. Using this method it is found that in Bufo regular is the increase in body water which follows pituitrin injection is the result of an increased rate of water uptake, together with a diminished urine flow. The excess water is mostly retained in the lymph spaces, while the water content of the tissues of the body increases very little. The bearing of these results on the problem of the identification of the substance or substances which elicit the amphibian water balance effect, and the biological significance of the organization of the anuran lymphatic system are discussed.
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord , Tuft P. H.
Published: April 2021

When a suspension of sea-urchin semen in sea water is diluted, the total O2 consumed and the rate of O2 uptake per spermatozoon are greater than before dilution. This is the Dilution Effect, first described by Gray (1928a). A further investigation of this phenomenon has been made, using the semen of Echinus esculentus. The form of the O2 uptake-time curve of such suspensions varies according to the ratio semen : sea water. In very dense suspensions d⩾5 × 109 sperm/ml.), the apparent low O2 uptake per unit quantity of spermatozoa is mainly due to inadequate O2 saturation of the lower layers of the suspension, in which the spermatozoa are virtually unable to respire. Such suspensions are not suitable for experiments in Warburg or Barcroft manometers. In dense suspensions (4 × 108 < d ⩽ 109 sperm/ml.) the Dilution Effect was observed when sea water was added to the suspension, in such proportions that the sperm density was only reduced by a factor of 1·14. No Dilution Effect occurred when isotonic ‘Analar’ NaCl was added in the same proportions. On the basis of the small dilution involved, and the negative results with ‘Analar’ NaCl, it is concluded that the Dilution Effect is not exclusively due to the sperm having more space to move after dilution and therefore being able to expend more energy. The Dilution Effect occurs when isotonic ‘Analar’ NaCl containing 1 p.p.m. CuCl2 is added to a dense sperm suspension, in the above proportions. Stimulation of O2 uptake is proportional, over certain limits, to the amount of CuCl2 added. Both CuCl, ZnCl2, and to a lesser extent CuSO4, have similar effects. In a particular experiment, egg-water and Cu salts were about equally efficacious in increasing the O2 uptake of a sperm suspension. The characteristic decline in the O2 uptake of dense suspensions can be partly reversed by the addition of Cu salts. In dilute suspensions (d⩽4 × 108 sperm/ml.), there is no Dilution Effect when sea water or CuCl2 are added in the above proportions. On the other hand, the decline in O2 uptake can be partly arrested by the addition of Cu salts. Diethyldithiocarbamate markedly inhibits the O2 uptake of unwashed seaurchin spermatozoa diluted with sea water. The inhibition does not take place in the presence of added CuCl2. Cu may therefore have a catalytic function in the metabolism of sea-urchin semen. The possibility that Cu lack is responsible for the reduced O2 uptake of spermatozoa in dense suspensions is considered.
A Note On the Copper Content of Sea-Urchin Semen and Sea Water
Authors: Barnes H. , Rothschild Lord
Published: April 2021

The copper content of semen, seminal plasma and coelomic fluid of Echinus esculentus has been determined. The average figures for sea-urchins examined immediately after collection were : semen, 1·33μg/ml.; seminal plasma, 0·50μg/ml.; coelomic fluid, 0·07μg./ml. The accuracy of the method of estimation was ± 0·08μg. Cu/ml. original sample, which means that the amount of Cu in coelomic fluid is not significant. This figure for coelomic fluid is considerably lower than that obtained by Webb (1937) in the only previous examination. The copper content of sea water (surface, off Keppel Pier, Millport) was 0·0064μg./ml.
Studies On Regional Specificity Within the Organization Centre of Urodeles
Authors: Waddington C. H. , Yao T.
Published: April 2021

In young gastrulae of Triton alpestris the median part of the organization centre immediately in front of the blastopore was excised and replaced after reversal of its anterior-posterior axis. Completely normal embryos developed in many cases, but in others there was some degree of microcephaly or spina bifida. Similar normal embryos can develop after exchange of the anterior and posterior regions of the organizer, either with normal or reversed orientation. The spina bifida which frequently appears is a consequence of the impediment offered by the graft to the normal gastrulation movements. Microcephaly may also result if the presence of the graft prevents the proper development of the anterior part of the archenteron roof. It may also be caused when the posterior organizer region is brought into the anterior region, if the host fails to convert it into anterior material. This occurs the more frequently the older the grafted posterior material is. Even at the end of gastrulation (slit yolk-plug stage) the regional character of the archenteron roof is not finally determined. A fairly normal embryo (with over-thick mesoderm) may develop if an extra archenteron roof is added with reversed orientation between the normal archenteron roof and the presumptive neural plate. The determination of the regional structure of the archenteron roof and the neural plate is discussed. Attention is drawn to the spatio-temporal factors involved in the production and diffusion of the evocator with the dynamic system of the gastrulating egg.
The Physiology of Carbon Dioxide Transport in Insect Blood
Authors: Levenbook L.
Published: April 2021

The pH of the blood of the third instar Gastrophilus larva is 6 ·64 at 38° C. with a pH-temperature coefficient of −0-007 Per 1° C. rise in temperature. The total CO2 content of the blood varies from 40·6 to 131·4 vol. % with an average of 72·4 vol. %. The CO2 content of the tissues minus the cuticle is very close to, and follows the variations in, the CO2 content of the blood. The CO2 tension in the blood is from 300 to 500 mm. Hg. From 30 to 50% of the CO2 is in solution, the rest in the form of bicarbonate. Carbamate formation does not occur in the blood. The ‘apparent’ dissociation constant for carbonic acid, , has a value of 6 ·08 (S.D. ±0 ·06) at 38° C. and 6 ·19 (S.D. ±0 ·13) at 16 ° C. CO2 dissociation curves have been drawn for 38 and 16 ° C. The slope of the curves indicates that the whole of the CO2 is given off at zero CO2 tension, and that the blood is adapted for functioning at high CO2 tensions.
The Physiology of Carbon Dioxide Transport in Insect Blood
Authors: Levenbook L. , Clark A. M.
Published: April 2021

In a previous paper (Levenbook, 1950) it has been demonstrated that carbon dioxide transport in the blood of the larva of Gastrophilus intestinalis de Geer (Diptera) occurs largely in the form of bicarbonate. It is highly probable that this also applies to most other insects. The quantity of bicarbonate present is a function of both the available base and the carbonic acid concentration, the latter in turn being directly proportional to the amount of gaseous CO2 existing in the blood. Wigglesworth (1939) has pointed out that except where the tracheolar endings are intracellular, the final gas transport between the tracheoles and the respiring tissues is through the insect’s blood. Accordingly it is of interest to determine whether or not insect blood possesses any special properties peculiar to this function of transporting carbon dioxide between the cells and the tracheoles.
The Physiology of Carbon Dioxide Transport in Insect Blood
Authors: Levenbook L.
Published: April 2021

One of the primary attributes of the internal medium of any organism is that it should maintain its normal hydrogen-ion concentration within certain rather narrow limits. Throughout life and, for different reasons, even after death, there is a continuous tendency for this pH to be depressed on account of the liberation into the blood of certain predominantly acidic metabolites, together with respiratory carbon dioxide. Although insects appear to support a wider range of pH change than do mammals, if their blood were insufficiently well buffered, its reaction would soon become outside the limits compatible with life.
Flight Recorders. A Technique for the Study of Bird Navigation
Authors: Wilkinson D. H.
Published: April 2021

Experiments on the homing ability of birds usually take the form of displacing a bird from its home, releasing it at a known time, observing its behaviour until out of sight and then noting the time when it returns, if at all, to its home. If the interval between release and return is that appropriate to direct flight from release point to home the interpretation is obvious; the bird has flown more-or-less straight home. If, as is more usual, the interval is considerably greater than the direct flight time the question arises as to whether the bird has been flying all the time or whether some substantial fraction of the time has been spent in other ways such as resting and feeding. It is of importance to be able to answer this question: a theory of bird homing based on methodical or random search would demand a considerable time spent actually on the wing, while a theory which postulates some genuine navigational ability on the part of the bird would admit of considerable resting periods and a time actually in the air no bigger than the direct flight time. The time spent in flying is, then, a vital datum which is lacking in conventional homing experiments.
Nitrogenous Excretion of Amphipods and Isopods
Authors: Dresel Elisabeth I. B. , Moyle Vivien
Published: April 2021

The nitrogen excretion of eleven species of amphipods and isopods, including marine, fresh-water and terrestrial forms, has been studied. All species are essentially ammonotelic, since more than 50% of the total soluble N.P.N. of the excreta was present in the form of ammonia throughout. The level of nitrogen excretion is appreciably lower in the terrestrial species than in any of the others, indicating that, in this group, adaptation to terrestrial conditions has been attended by a general suppression of nitrogen metabolism rather than by a transformation of ammonia to other, less toxic products. Some 5-10% of the total soluble N.P.N. was present as urea in the case of the fresh-water amphipod, Gammarus pulex, and as uric acid in the terrestrial isopods as well as the fresh-water isopod, Asellus aquaticus. It is suggested that these minor excretory components might originate from purines as a result of the loss of one or more of the uricolytic enzymes. In association with the excretion of uric acid some retention of this insoluble compound usually occurs, and it was found that among the terrestrial species the amount so stored parallels the degree of morphological and physiological adaptation to terrestrial conditions. The greatest accumulation of uric acid was, however, observed in the fresh-water species, A. aquaticus, and although such a storage cannot necessarily be taken as evidence for a partially uricogenic metabolism, this possibility must be borne in mind.
Refinements in Polarized Light Microscopy
Authors: Swann M. M. , Mitchison J. M.
Published: April 2021

Various measures to increase the sensitivity of the polarizing microscope for visual observation are discussed. These include choice of polarizing apparatus, reducing condenser and objective aperture, reducing lamp iris, blooming lenses, use of mica plate compensators and use of bright light sources. By such means as these it is possible to detect retardations down to 0.28 A., or 1/20,000th of a wave-length. A photographic method for measuring retardations down to the same limit in small biological objects, is also described.

We are deeply indebted to Mr E. W. Taylor of Messrs Cooke, Troughton and Simms Ltd., for his great help in fitting our microscope with double Polaroids and a graduated compensator mount, as well as for blooming our lenses and making special low retardation mica plate compensators. We are also indebted to Dr L. E. R. Picken and Dr A. F. Hallimond for helpful suggestions at various stages of the work.
An Electron Diffraction Study of the Crystalline Structure of the Lipids in the Pupal Exuviae of Calliphora Erythrocephala
Authors: Hurst H.
Published: April 2021

Electron diffraction techniques have been extensively used for the direct crystallographic examination of thin films of fatty materials, but they have hitherto not been applied to the study of natural membranes. These techniques provide more information than diffraction of X-rays about the atomic and molecular organization of surface structures. X-ray diffraction methods have been used successfully by Fraenkel & Rudall (1940, 1947) for elucidating the molecular organization of the chitin and protein components of the bulk cuticle framework in blowfly larvae ; but the thin lipid-rich epicuticle constitutes a small proportion of the entire cuticle, and would not contribute effectively to the observed diffraction patterns.
Studies on Haemovanadin. III. Some Physiological Properties of Haemovanadin, The Vanadium Compound of the Blood of Phallusia Mamillata Cuv*
Authors: Califano Luigi , Boeri Enzo
Published: April 2021

It has been known since 1911 (Henze) that the blood of Phallusia mamillata Cuv. contains vanadium, which is found in special cells, called vanadocytes by Webb (1939). Webb estimated that the vanadocytes constitute about 60% of the blood cells and the blood cell volume amounts to between 1 and 2% of the total blood volume. It was found by Henze that the inner medium of the vanadocytes is very acid, due to free sulphuric acid which is present in a concentration of about 3%. According to Webb, the vanadium content of the animal amounts to about 0-15% of the dry weight of the body, and three-quarters of the total amount of vanadium is present in the blood, 15 % in the gut and associated viscera and 10% in the mantle and branchial sac.
The Diurnal Variations in the Tissue Glycogen Content and Their Relation to Mitotic Activity in the Adult Male Mouse
Authors: Bullough W. S. , Eisa E. A.
Published: April 2021

A description is given of the hour-to-hour variation in the liver glycogen content in adult male mice, and it is shown that the concentration is highest while the animals are asleep and lowest while they are awake. A similar cycle is also described in the glycogen content of the skin. Histologically it is shown that a high proportion of the skin glycogen lies in the cytoplasm of the epidermal cells, and that during sleep both the epidermal glycogen content and the epidermal mitotis rate increase considerably. The skin glycogen content and the epidermal mitotic activity also show a marked increase after a subcutaneous injection of 20 mg. starch, while they are both abnormally depressed after two injections of unit insulin. These results, together with others previously reported, are in agreement with the theory that at the onset of sleep glucose is deposited from the blood into the tissues where it appears in the form of glycogen. Since it is known that glucose, or glycogen, is a critical substance affecting mitotic activity in the adult mouse, it is logical to find that an increase in the epidermal glycogen content is accompanied by a greatly increased mitosis rate. On waking, the reverse process takes place, glycogen being withdrawn as glucose into the blood and mitotic activity falling to a low level.
Changes in the Behaviour of Honey-Beesfollowing Their Recovery From Anaesthesia
Authors: Ribbands C. R.
Published: April 2021

Chloroform anaesthesia did not impair the memory, change the foraging behaviour, or reduce the longevity of the treated bees; chloroform is therefore a satisfactory anaesthetic for use in experiments on bee behaviour. Carbon dioxide anaesthesia did not impair the memory of treated bees, but it did induce a permanent change in their behaviour. Their pollen-collecting tendencies were either eliminated or suffered very marked reduction. Experiments with foraging bees of known age indicated that the carbon dioxide treatments had no direct effect on longevity. Treatment of recently emerged bees with carbon dioxide eliminated all or most of their brood-rearing and wax-secreting activities and caused them to forage at an early age. Foraging life is more hazardous than life within the hive, and therefore the expectation of life of these carbon-dioxide treated bees was less than that of the controls. The effects of nitrogen anaesthesia were similar to those obtained with carbon dioxide. The factor common to both treatments is oxygen lack. The theoretical and practicable possibilities of these results are discussed.
Central Nervous Function and Changes in Brain Metabolite Concentration
Authors: Chance M. R. A. , Yaxley D. C.
Published: April 2021

The content of glycogen and lactate in mouse brain has been estimated after a new extraction procedure which has been demonstrated to involve only a slight loss in amount of these two metabolites in comparison with extraction following freezing in situ. Five different methods of precipitating convulsions produced increases in the amount of lactate concentration at both subconvulsive and convulsive levels, but glycogen increased appreciably only when these methods produced a convulsion. It is concluded that glycogen increase in the mouse brain is specifically related to the occurrence of epileptic discharge in the brain. This increase has been shown to occur in all parts of the brain, though in varying degrees. Previous studies on these brain metabolites are discussed in the light of these results.
A New Micro-Respirometer with Automatic Setting and Recording Apparatus
Authors: Tuft Peter
Published: April 2021

The instrument was designed to measure the O2 uptake of living material which consumes between 0·01 and 5·0 μl. O2/hr. Its accuracy is + 0·001 μ1., and it has the following advantages over other micro-respirometers of similar sensitivity.
The Hatching Mechanism of Muscid Eggs (Diptera)
Authors: Davies Lewis
Published: April 2021

Certain Muscid eggs are shown to change their shape almost simultaneously with changes in the relative humidity of the air in their immediate vicinity. Evidence is produced that these shape changes are caused by the effect of humidity on the chorion. The net effect of the shape changes appears to be the setting up of increasing strain in the chorion, making it progressively easier for the larvae to rupture their shells, with increasing humidity. These shape changes therefore provide an explanation for certain well-known humidity effects on the hatching of Muscid eggs.
The Development of Motor Responses in the Stomach of the Foetal Sheep
Authors: Duncan D. L. , Phillipson A. T.
Published: April 2021

Knowledge of the movement of the gut in the mammalian foetus is mainly derived from observations on small laboratory animals. Yanase (1907) made a systematic study of pre-natal intestinal movement in the guinea-pig, and observed that the appearance of peristalsis coincided with the time of development of the longitudinal muscle of the gut, at about the 27th day of gestation. At the stage when circular muscle alone was present, he was able to elicit only local constriction by mechanical or faradic stimulation. Foetal gastric movement was observed in the rabbit (Tani, 1927) and in the cat by Friedman (1934), Windle & Bishop (1939), and Becker & Windle (1941). The last-named described rhythmic and persistent gastric peristalsis in cat foetuses of 35–40 days. Becker, Windle, Barth & Schultz (1940) found that thorotrast injected into the amniotic sac of the guinea-pig circulated through the alimentary tract of the foetus from the 42nd day onwards; and human foetal swallowing is said to occur from the fifth month (Windle, 1940). While there is evidence, therefore, that alimentary tract movement commences in pre-natal life, nothing is known of the factors controlling the onset of movement or of the nature of the individual movements.
Fermentation in the Rumen of the Sheep
Authors: Gray F. V. , Pilgrim A. F. , Weller R. A.
Published: April 2021

It is now generally accepted that the fermentation of carbohydrates in the rumen gives rise to the formation of large amounts of the lower volatile fatty acids ; but the fact that these acids are absorbed in considerable amounts and at different rates from the rumen into the blood stream has made it clear that in vitro studies of the fermentation processes are necessary in order to ascertain the actual quantities in which they are made available to the ruminant.
Radiographic Studies on the Formation of the Hen’s Egg Shell
Authors: Bradfield J. R. G.
Published: April 2021

Radiographic methods have been used to study the rate of deposition of the hen’s egg shell and the changes in volume and orientation undergone by the egg in the shell gland. Shell deposition commences about 5 hr. after the yolk is ovulated and several series of radiographs were obtained tracing the process from these earliest stages through to the fully calcified shell. From radiographs of calcium carbonate-gelatin mixtures it was found that, for a series of comparable objects differing only in calcium carbonate content, the densitometer readings on their radiographs were directly proportional to the density of calcium carbonate traversed by the X-rays in each object. Hence, densitometer measurements on the periphery of the shell in each of a series of radiographs taken during the development of a single egg shell give values which are proportional to the density (or thickness) of calcium carbonate traversed by the tangential rays. It is shown that the radial thickness is closely proportional to the square of these values. Plotting these squared densitometer readings against time indicates that the rate of deposition of mineral matter in the shell follows an S-shaped curve, with a marked acceleration in shell deposition 5–6 hr. after its onset. During its first few hours in the shell gland, the egg undergoes a 25 % osmotic increase in volume. This swelling is brought to a fairly abrupt halt by the increase in the rate of shell deposition and the consequent increase in the impermeability and rigidity of the shell. Throughout all but the last hour or two of its 20 hr. stay in the shell gland, the egg lies with its pointed end caudal. Shortly before it is laid, however, it usually undergoes a 180° rotation in a horizontal plane. Thus the blunt end finally becomes caudal and emerges first when the egg is laid. During the rotation, the egg sinks to a more ventral position. This is necessary because, in most hens, the length of the egg plus the thickness of the walls of the shell gland is greater than the width of the pelvis. The possible significance of the S-shaped curve of shell deposition is discussed. The volume, shape and orientation of the egg are considered in relation to the needs of the chick embryo and to the characteristic structure of the bird’s oviduct and pelvis.
The Body Temperature of Woodlice
Authors: Edney E. B.
Published: April 2021

Measurements by means of thermocouples, accurate to 0.1° C., were made of the body temperature of the woodlice Armadillidium, Porcellio, Oniscus and Ligia, and of the cockroach Blatta, both alive and dead, in a stream of saturated or dry air at both 20 and 37° C. No difference in temperature depression was found between living and dead woodlice, and in all the animals used there was, after equilibration, no difference greater than 0.1° C. between the air temperature and body temperature if the air were saturated with water vapour. In dry air, the body temperature of all the animals except Ligia settled down after at most 25 min. to a steady temperature which was lower than that of the surrounding air. The body temperature of Ligia continued to rise slowly for at least 2 hr., though remaining well below that of the environment. After 30 min. in dry air at 20 and 37° C. respectively, mean temperature depressions (of at least three readings at each temperature for each species) were, in degrees centigrade: Ligia, 2·6 and 6·8; Oniscus, 1·5 and 2·7; Porcellio, 0·4 and 1·3; Armadillidium, 0·5 and 1·8; and the cockroach Blatta, 0.7 and 2.4. The order of the Certain anomalies which appear when these figures are compared with previously established figures for insects are probably the result of differences in permeability of the integument and in the site of water loss. The ability to evaporate water rapidly, and thus to cool the body, may be of survival value when woodlice are exposed to high temperatures for short periods, particularly in littoral forms which may well have been intermediate in the evolution of terricolous from maricolous isopods.
Oviposition Behaviour in the Two Strains of the Rice Weevil, Calandra Oryzae Linn. (Coleopt., Curculionidae)
Authors: Segrove F.
Published: April 2021

A knowledge of the biotic potential of an insect population, i.e. of its rate of multiplication under various conditions, is of obvious importance in the case of grain-infesting insects. Such knowledge is available for very few species, for its computation requires exact information of certain biotic constants (Chapman & Baird, 1934) which can be determined only by protracted experiment. Not the least important of these is one which is a function of the fertility and rate of oviposition, and the primary aim of the present investigation has been to obtain information on this subject for the rice weevil, Calandra oryzae.

Previous work on oviposition has frequently fallen short of requirement for several reasons. Where full-scale experiments have been carried out (e.g. Kunike (1936) and Lavrekhin (1937)), the control of environmental conditions has been too inadequate for the results to have any great value. Where a more rigid control has been attempted short-term experiments on rates of oviposition have usually been conducted (e.g. MacLagen & Dunn (1936), Crombie (1942), Richards and his co-workers (1944,1947)), and not infrequently selected females have been employed. The results, in consequence, though of value in other directions, are seldom if ever a reliable index of total fertility and throw little light on the general pattern of oviposition. Only in the cases of C. granaria (Eastham & McCully, 1943) and the small race of C. oryzae (Birch, 1945 a) have full data been obtained under adequately controlled conditions.

In C. oryzaeRichards (1944) has demonstrated that there are two very distinct strains which differ principally in size, and one of these, the small strain, has already been the subject of full investigation (Birch, 1945 a, b). In the present work, there-fore, attention has been mainly directed towards the behaviour of the large strain, a limited number of parallel experiments being carried out with the small weevil for comparative purposes.
The Colour Change of the Minnow (Phoxinus Laevis AG.)*
Authors: Healey E. G.
Published: April 2021

Records were made of the times required for the melanophores of the normal minnow to reach equilibrium when the fish is transferred from one to another of the following conditions : on an illuminated white background; on an illuminated black background; in darkness. These times give further evidence of the parts played by nervous and hormonal mechanisms in the colour change of the minnow. After section of the spinal cord between the 5th and the 12th vertebrae the fish darkens but gradually becomes pale again if kept on an illuminated white background. Such fish can still show a slow colour change: dark on a black background, pale on a white background and intermediate in darkness. Observations of the times required for these colour changes in the spinal minnow show that these no longer resemble those associated with the unoperated fish; rather, they resemble the time intervals associated with amphibian colour change. Further consideration of the times required for colour change in the spinal minnow indicate that there is not only a hormone causing aggregation of the melanophores but also a hormone causing melanophore dispersion. The part played by double innervation of the melanophores is considered.
The Distribution of Electromotive Forces in the Neighbourhood of Apical Meristems
Authors: McAulay A. L. , Ford J. M. , Hope A. B.
Published: April 2021

A research is described using different methods of experiment on two contrasted types of apical meristems with the object of measuring the permanent electrical field inside and outside the plant in the neighbourhood of the apical meristem under conditions of specified control. Most of the experiments were performed on 3-5-day-old maize seedling roots and turnip seedling hypocotyls. The conditions of measurement were such as to produce minimum stimulation of the plant. The general results were checked by experiments with other plants. The measured p.d. is a result of e.m.f.’s which are unchanged when supplying current of the order of 10−8 amp. through external conductors. Both turnip hypocotyls and sections of couch grass stems generate power of the order of 10−9 W. without polarizing (see text). In these experiments the equivalent resistance of the plant materials obeyed Ohm’s law. The average potential gradient along the surface of thirty-four turnip hypocotyls in the neighbourhood of the apical meristems was found to be 7·1 ±3·8 mV./mm. (over 6-8 mm.). The surface of the meristematic region is positive to that of older tissue. The corresponding average for twenty-five maize roots was 5·7 ± 2·4 mV./mm. (over 6—8 mm.). There are transverse e.m.f.’s between the outside and inside of the plants distributed radially from the stele to the root exodermis and hypocotyl epidermis. The inside is always negative with respect to the outside. The radial e.m.f. is larger in the meristematic region than elsewhere: In turnip hypocotyls, the radial e.m.f. at the meristematic region varies between 44 and 103 mV. ; 5−10 mm. from the apex it is 17−60 mV. In maize roots, the corresponding figures are 17−77 and 6−33 mV. There is a small but possibly not significant potential change along the axis in both the organs considered, possibly 1 mV./mm. Under the conditions of the experiment, the interior of the meristem was found to be negative with respect to the rest of the axis. Points 4 and 5 are summarized in Fig. 4A. The theory that the interior of a mass of meristematic tissue is electrically negative to older tissue is discussed in the fight of the experimental evidence and with regard to the limitations of the technique used.
Observations on the Distribution of Inorganic Phosphorus, Soluble Calcium and Soluble Magnesium in the Stomach of The Sheep
Authors: Garton G. A.
Published: April 2021

In a preliminary survey of the distribution and fate of phosphorus-containing compounds in the alimentary tract of the sheep it was decided to estimate the inorganic phosphate levels of the fluid of the various divisions of the stomach. Information on this topic is very scanty, the only figure for phosphorus in sheep rumen liquor which could be found in the literature being 87 mg. P/100ml. (Brünnich & Winks, 1931). The initial experiments showed that inorganic phosphate occurred in higher concentration in abomasal liquor than was anticipated, and this led to an examination of the levels of soluble calcium and magnesium. Calcium and magnesium were chosen because their fate in the alimentary tract is often closely linked with that of inorganic phosphate. Some observations on the composition of sheep gastric juice were also made as one of the animals available for this investigation had an abomasal pouch of the Hollander type.
Water Uptake and Moulting in Bufo Regularis Reuss
Authors: Ewer R. F.
Published: April 2021

In Bufo regularis Reuss moulting is accompanied by an increase in the rate of water uptake through the skin. An increase in urine flow is also observed, starting some time after the rate of water uptake has begun to increase. No increase in rate of water uptake occurs following thyroxine feeding on 4 successive days. The possibility that posterior pituitary activity is responsible for the observed increase in rate of water uptake during moulting is discussed.
The Fertilization Reaction in the Sea-Urchin
Authors: Rothschild Lord , Swann M. M.
Published: April 2021

Unfertilized eggs of the sea-urchin (Psammechinus miliaris) were left for known but varying times in contact with homologous sperm suspensions containing known numbers of spermatozoa. Counts were made of the numbers of fertilized and unfertilized eggs at times ranging from o to 300 sec. after mixing. If spermatozoa are considered as particles moving in random directions, the frequency of sperm-egg collisions can be calculated if the density and mean speed of the sperm suspension are known. The information in (1) and (2) enables an estimate to be made of the probability of a successful sperm-egg collision. The estimated probability of a successful collision, p, varies with sperm density, d. At the lowest density used, 7·44 ×104/ml., p was found to be 0·226. At the highest density, 9·62 ×106/ml., p was about 0·011. The inverse relationship between p and d may be due to sperm-sperm interactions of a physical nature. The presence of jelly round the eggs increases p. This disposes of the possibility, raised in the past, that egg jelly may have an adverse effect on the fertilizing capacity of homologous spermatozoa under normal conditions of fertilization. The technique of subjecting eggs to a pre-determined number of collisions facilitates investigation of the conduction time of the block to polyspermy. Preliminary experiments suggest that the conduction time may be of the order of seconds rather than fractions of a second. Sources of error arising from the ‘kinetic ‘treatment of sperm suspensions are discussed in detail. One source of error concerns the alleged chemotaxis of spermatozoa towards eggs and egg secretions. No chemotaxis was observed.
Protoplasmic Structure and Mitosis
Authors: Swann M. M.
Published: April 2021

The present paper is the first of a series dealing with the birefringence of mitotic figures in the eggs of the sea-urchin Psammechinus miliaris. Living eggs have been examined using time-lapse photography, and retardation curves for the mitotic figures constructed from densitometrie measurements made on the film negatives. In the case of the aster, an integral equation relating retardation and coefficient of birefringence can be formulated and solved exactly to give coefficient of birefringence. In the case of the spindle, coefficient of birefringence can only be calculated approximately. In both asters and spindles, the coefficient of birefringence is nil at the centres, rises to a maximum at 5 or 6 μ out, and then falls to a minimum at the equator of the spindle or the periphery of the aster. The rise in coefficient of birefringence round the centre is not as sharp as might be expected, and there is some evidence that orientation is built up gradually over a distance of a few microns. The fall in coefficient of birefringence away from the maximum is approximately an inverse square in the case of the spindle. In the aster it falls off somewhat more rapidly. Since the density of material does not vary from point to point, this fall must be due to changes in molecular and micellar arrangement, or to a decreasing proportion of oriented material. The classical conception of the spindle and asters as structures built up of discrete fibrils radiating from the centres, would be expected, for geometrical reasons, to give an inverse square fall in proportion of oriented material. While, therefore, a homogeneous structure with varying molecular and micellar arrangement cannot be ruled out, it is possible that the mitotic figure consists of definite fibrils radiating from the centres. Evidence from other sources supports this view, and suggests that the fibrils must be submicroscopic in size.
Protoplasmic Structure and Mitosis
Authors: Swann M. M.
Published: April 2021

The mitotic figure of the sea-urchin egg is most strongly birefringent at metaphase. During anaphase this birefringence decreases considerably, but the spindle and asters both grow in size. These changes have been investigated quantitatively by constructing curves of retardation and coefficient of birefringence across the mitotic figure, using techniques described in an earlier paper. The decrease of birefringence in the spindle starts at the equator, and then moves, in the course of a few minutes, to either pole. Only when the decrease has reached the spindle poles does it begin in the asters, where it moves outwards from the centres. These changes resemble the movements of the chromosomes, which also start at the equator in metaphase, and move in separate groups to the poles during anaphase. By examining single eggs in anaphase up to the moment of fixation, and then staining them to show the chromosomes, it is established that the regions of, decreasing birefringence actually correspond to the position of the chromosomes. Since the chromosomes are too small to be the direct cause of the decrease in birefringence, it is concluded that they are producing the decrease indirectly by initiating a structural change in the spindle and asters. The possible mechanisms for this change are discussed. It is concluded that the chromosomes must be releasing an active substance, for which the term ‘structural agent’ is suggested. The growth of the mitotic figure takes the form, in the spindle, of an increase in length, and in the asters, of an increase in size. It is accompanied by an increase in coefficient of birefringence, though this is to some extent masked by the decrease in birefringence referred to earlier. The increase in coefficient of birefringence affects the whole mitotic figure from the very beginning of anaphase, and is not therefore relatable to the position of the chromosomes. For this reason it might be due to a number of different mechanisms, but as it starts at the same moment as the decrease in birefringence, it is tentatively assumed to be due to the release of a second ‘structural agent’. The increase in coefficient of birefringence is probably due to the orientation of new material. The decrease is more likely to be due to changes in molecular and micellar arrangement; it would be consistent with a contractile mechanism in the spindle. The implications of these findings are discussed in a concluding section.
Factors Determining the Temperature of Terrestrial Arthropods in Sunlight
Authors: Parry D. A.
Published: April 2021

A study has been made of the factors determining the temperature of terrestrial arthropods in sunlight. For such animals the most important forms of heat exchange, which determine the equilibrium temperature, are radiation and convection. Compared with these, evaporation and metabolism are insignificant except under unusual circumstances. Convection depends on the size of the body in such a way that the temperature of similar animals in similar circumstances will vary as about the square root of the linear dimension. Other morphological features affecting temperature are shape, orientation and colour. The factors on which such animal temperatures depend are difficult to measure, and it is unlikely that temperatures will ever be accurately deduced from heatbalance considerations. But the insignificance of metabolism and evaporation implies that the temperature of the living animal in a given situation is likely to be very similar to that of an inanimate body of the same approximate size, shape, colour and orientation. If the temperature of such a body can be measured it forms a type of thermometer giving information of direct biological significance. Terrestrial arthropods may be as warm as, or warmer than, the ‘warm-blooded animals, particularly on the ground where conditions change rapidly over small distances so that animal temperatures must be profoundly affected by behaviour. Laboratory data on evaporation at high temperatures do not apply directly to conditions in the field, because an animal warmed by the sun will not necessarily lose water at the same rate as one warmed to the same temperature by warm air at the same relative humidity.
The Growth of Brown Trout (Salmo Trutta Linn.)
Authors: Brown Margaret E.
Published: April 2021

Studies of scale development in fishes which live in temperate zones have suggested that variations in the rate of growth of the fish may lead to the development of annuli and circuli on the scales. These variations in growth rate might result from : seasonal variations of the physical environment, especially of temperature and illumination;variations in the quality and quantity of the food supply; andphysiological changes within the fish, such as annual cycles of maturation of the gonads and spawning. The second and third factors might well be related ultimately to the first.