bluuebunny/crossref_metadata_2025 huggingface dataset:
A test of altitude-related variation in aerobic metabolism of Andean birds
Authors: Gutierrez-Pinto Natalia , Londoño Gustavo A. , Chappell Mark A. , Storz Jay F.
Published: April 2021

Endotherms at high altitude face the combined challenges of cold and hypoxia. Cold increases thermoregulatory costs, and hypoxia may limit both thermogenesis and aerobic exercise capacity. Consequently, in comparisons between closely related highland and lowland taxa, we might expect to observe consistent differences in basal metabolic rate (BMR), maximal metabolic rate (MMR) and aerobic scope. Broad-scale comparative studies of birds reveal no association between BMR and native elevation, and altitude effects on MMR have not been investigated. We tested for altitude-related variation in aerobic metabolism in 10 Andean passerines representing five pairs of closely related species with contrasting elevational ranges. Mass-corrected BMR and MMR were significantly higher in most highland species relative to their lowland counterparts, but there was no uniform elevational trend across all pairs of species. Our results suggest that there is no simple explanation regarding the ecological and physiological causes of elevational variation in aerobic metabolism.
Investigations on the Regional Determination of the Central Nervous System
Authors: Nieuwkoop P. D.
Published: April 2021

With the aseptic operation method of Woerdeman (1930) it is possible to rear duplicitas larvae, formed after grafting of the dorsal blastoporal lip in the place of the ventral one at the early gastrula stage (Spemann, 1918), till an age of about 4 weeks, a time at which they have completely consumed their yolk material. Various forces acting in the normal development and in the development of the duplicitas larvae are discussed in connexion with the external form and the internal organization of the latter. The sources of errors in the method of graphic reconstruction of the brain used in this investigation are checked and their elimination is discussed. The structure of the duplicitas shows that there exists a mediolateral and probably also a cranio-caudal regulation in grafts of the dorsal blastoporal lip of the early gastrula. In the brain one may distinguish between ‘primary’ structures which are always present, and ‘secondary’ structures which are more variable. Therefore, one may probably divide the causal analysis of the development of the central nervous system into the determination of the ‘ground plan’ of the primary structures and the more dependent development of the ‘secondary ‘ones (specific formations). The brains of the secondary embryonic rudiments of these duplicitas are formed in all cases up to a certain level; caudally to this level the brain-parts are normally proportioned, but the most anterior part may be reduced in size. This material can be arranged into a complete regression series, beginning with the reduction of the telencephalon and ending with a completely acephalic embryo. From this development one may conclude that the determination of the central nervous system occurs in a large number of successive zones, which are qualitatively ‘equivalent’, and which are determined by (qualitatively or quantitatively) different values of the organizing ‘agent’. There are indications that the infundibulum and hypophysis are determined by a triple contact between presumptive neural plate, prechordal plate and cephalic ectoderm after the appearance of the neural plate. After special staining these incomplete nervous systems may form a very important source of data for the causal analysis of the development of tracts and nuclei in the central nervous system. With the conclusions drawn from these experiments and the data given in the extensive literature on this subject, a new working hypothesis on the determination of the central nervous system is put forward. This theory involves the assumption (among others) of an equilibrium reaction between a strong mesodermal and a weak ectodermal gradient. The character of the determination process probably changes from being at first purely quantitative to become qualitative with increasing age. Finally, the regional determination of the secondary rudiment in duplicitas is probably determined by a triple interaction between the induction field of the graft, the primary regional structure of the ectoderm and the regional influences of the primary rudiment.
Experimental Modification of the Sexual Cycle of the Greenfinch
Authors: Damsté P. H.
Published: April 2021

’Mewing’ of song-birds is a traditional practice of Dutch bird-catchers who make use of it to produce singing decoys in the autumn. The birds are encaged early in May, the daylight is progressively reduced by means of curtains during May and the birds are kept in darkness throughout June, July and the first half of August. From the middle of August onwards the curtains are gradually opened and by the end of the month the birds are in daylight and in full song once more. This procedure was carried out with the greenfinch (Chloris chloris) under laboratory conditions in order to study the behaviour, song and moulting of the birds and the histology of their gonads before, during and after mewing. In the early stages of mewing the testes decrease in size till in total darkness they have the same diameter as the inactive testis. When the birds are exposed to normal daylight again the testes enlarge rapidly until after some weeks of increasing spermatogenesis they are fully mature. By this time the birds are in full song and it is likely that song coincides with sexual maturity and is induced by the male sex hormone. The diameter of the testis tubules varies in the same way as the diameter of the gonads. In the middle of October, after some weeks of sperm production, regression of the testis sets in. During the ensuing stage of sexual inactivity some birds were exposed to increasing quantities of (electric) light from the beginning of December until the beginning of February. These birds showed increasing spermatogenesis and developed their full song. Thus by means of mewing and ‘extra lighting’ it was possible to bring birds into breeding condition three times within one year.
Visual Responses of Mosquitoes Artificially Rendered Flightless
Authors: Rao T. Ramachandra
Published: April 2021

Most females of Anopheles maculipennis and Culex molestus which had been rendered flightless by removal of wings or by sticking the wings together, tended to move towards a black vertical band when it was presented to them in an arena uniformly illuminated from below. The narrowest width of the band to which they could consistently respond was 0 · 5 cm. at a distance of 3 · 5 cm. corresponding to an angle of about 8 °.

When the edge of a wide black band was exactly in front of the mosquito or at about 45 ° to one side the movement towards it was consistent, but when the band was placed more and more posteriorly consistency of the responses progressively decreased.

When offered simultaneously two black bands of equal or different widths the movement was to one of them. If a new band came into the view when the mosquito was already moving towards another, a turning response towards the new one took place very frequently.

Unilaterally blinded specimens performed circus movements in uniform light. When a narrow black band came into the visual field of the functional eye there was an immediate turning response towards it.

The negative phototaxis continued even at and after dusk at a time when flying mosquitoes were showing natural movement towards the evening light. Reduction of intensity of illumination and also the natural fading of the light at dusk both failed to bring about a reversal of response. For some undetermined reason mosquitoes rendered flightless always tend to move away from light.

The mechanism of orientation seems to be in conformity with current ideas of negative phototropotaxis. No evidence of a photohorotaxis was secured.
The neuropeptide RhoprCCHamide2 inhibits serotonin-stimulated transcellular Na+ transport across the anterior midgut of the vector of Chagas disease, Rhodnius prolixus
Authors: Capriotti Natalia , Gioino Paula , Ons Sheila , Ianowski Juan P.
Published: April 2021

Rhodnius prolixus is a blood-feeding insect vector of Trypanosoma cruzi, a protozoan parasite that causes Chagas disease. During each blood meal, the animals ingest large volumes of blood, that may be up to 12 times the unfed body mass. These blood meals impose a significant osmotic stress for the animals due to the hyposmotic condition of the ingested blood compared with the insect's hemolymph. Thus the insect undergoes a massive postprandial diuresis that allows for the excretion of the plasma fraction of the blood in less than two hours. Diuresis is performed by the excretory system, consisting of the Malpighian tubules and gut, under the control of diuretic and anti-diuretic factors. We investigated the ion transport machinery triggered by stimulation with the diuretic factor serotonin in the anterior midgut (i.e. crop) and the effect of the diuretic modulator RhoprCCHamide2. Ussing chamber assays revealed that serotonin-stimulated increase in transepithelial short-circuit current (Isc) was more sensitive to the blockage with amiloride than 5-N-ethyl-N-isopropyl amiloride (EIPA), suggesting the involvement of Na+ channels. Incubation in Na+-free, but not Cl−-free saline, blocked the effect of serotonin on Isc. Moreover, treatment with Na+–K+–2Cl− cotransporter (NKCC) and Na+–Cl− cotransporter (NCC) blockers had no effect on fluid secretion but was blocked by amiloride. Blockage of Na+/K+-ATPase with ouabain inhibited Isc but the H+-ATPase inhibitor bafilomycin had no effect. The neuropeptide RhoprCCHamide2 diminished serotonin-stimulated Isc across the crop. The results suggest that Na+ undergoes active transport via an apical amiloride-sensitive Na+ channel and a basolateral ouabain-sensitive Na+/K+-ATPase, while Cl− is transported through a passive paracellular pathway.
A Further Study of the Reactions of Fish to Toxic Solutions
Authors: Erichsen Jones J. R.
Published: April 2021

This paper records some further observations on the reactions of fish to toxic solutions. The method of experimentation resembles that described in a previous paper by the writer (Jones, 19476). In every case the solution is presented as an alternative to the Aberystwyth tap water, which is well aerated, very soft, of pH 6·8,

In experiments with sodium sulphide a supply system is arranged in which dilute sodium sulphide solution, brought to pH 6·8 by the addition of sulphuric acid, is automatically made up as it runs into the observation vessel. Gasterosteus aculeatus L. reacts negatively to a 0·001N solution almost immediately; at greater dilution the ‘reaction time’ lengthens, at 0·00008N is about 47 min. Over the concentration range tested the reaction time is always shorter than the survival time.

Gasterosteus is positive to 0·04N lead nitrate. As a positive reaction is also displayed to equivalent concentrations of calcium nitrate, sodium nitrate and sodium chloride it is possible that the osmotic pressure of the solution is its attractive feature.

At 0·01 N the positive response to lead nitrate disappears and at 0·004N is replaced by a very definite negative reaction which is maintained down to 0·00002 N. The minnow (Phoxinus phoxinus L.) is also negative to dilute lead nitrate and will detect and avoid a 0·000004 N solution.

Gasterosteus will avoid water more acid than pH 5·6 or more alkaline than pH 11·4. Over the range 5·8-11·2 the fish are indifferent or very vaguely positive.

Gasterosteus is negative to 0·04 and 0·01 N ammonia solution, positive to 0·001 and 0·0001 N. The general result with ammonia is thus the converse of that observed with lead nitrate.
The Oxygen Requirements and Thermal Resistance of Chironomid Larvae from Flowing and from Still Waters
Authors: Walshe Barbara M.
Published: April 2021

Extensive surveys of the distribution of chironomid larvae have established the fact that the majority of species are strikingly restricted in their habitat: the causes of this specialization, however, remain largely undetermined. For a few species comprehensive ecological work has made it possible to deduce the factors important in determining distribution (Thienemann, 1923, 1928; Lenz, 1925), but an experimental attack on the physiology and behaviour of larval and adult chironomids in relation to their choice of habitat remains almost a virgin field.
Third Report On A Test of Mcdougall’s Lamarckian Experiment on the Training of Rats
Authors: Agar W. E. , Drummond F. H. , Tiegs O. W.
Published: April 2021

Our First Report on this experiment was published in 1935, and dealt with the first five generations. The Second Report, 1942, included the first twenty generations. This Third Report adds another sixteen generations, and reviews the whole experiment up to date.
The Sensory Physiology of the Sheep Tick, Ixodes Ricinus L
Authors: Lees A. D.
Published: April 2021

The sensory perceptions of several species of ticks, notably Argas persicus (Hindle & Merriman, 1912), Boophilus annulatus and Rhipicephalus sanguineus (Krijgsman, 1937), Ixodes ricinus (Totze, 1933) and I. persulcatus (Mironov, 1939), have been studied systematically in the laboratory. There are, in addition, many scattered references in the literature to the behaviour of ticks and some incomplete descriptions of their sense organs. The chief aim of the present work has been to investigate the orienting reactions of the sheep tick, and the role of the special senses, in relation particularly to those stimuli the tick will encounter in its natural environment. With such an object in view, a knowledge of the ecology and behaviour is clearly a desirable, if not an essential, starting-point. There was little understanding of these subjects at the time Totze was writing and, in consequence, there was a tendency for the laboratory observations to lack meaning or to acquire a distorted significance. A fresh examination of the sensory physiology is justified by the increased knowledge of the ecology of the sheep tick in Britain, a subject which has been studied intensively from 1932 onwards. As a preliminary to the present work some weeks were spent observing the behaviour of a population of active ticks under natural conditions. These observations proved of value both by suggesting lines of investigation and, finally, in attempting an interpretation of the significance of the reactions observed in the laboratory.
Vapour Pressure Changes in the Frog’s Egg at Fertilization
Authors: Picken L. E. R. , Rothschild Lord
Published: April 2021

The vapour pressure of unfertilized and fertilized frogs’ eggs has been measured by the differential thermal method. The following results were obtained ; they are expressed as decimal fractions of the vapour pressure of a 1 % aqueous solution of sodium chloride : These results are in serious disagreement with those of Backmann & Runn-ström (1912) and Backmann & Sundberg (1912), but in general agreement with those of Krogh et al. (1938). It is concluded that while there is probably a slight difference between the vapour pressure of fertilized eggs in tap water half an hour after fertilization, and of unfertilized eggs half an hour after transfer to tap water, the difference is negligible after 3 hr. The initial difference may be due to a more rapid interchange between egg and environment in fertilized eggs. In the case of unfertilized eggs, the effect of transfer to a hypotonic medium may be interpreted as an abortive response to a parthenogenetic stimulus.
The Theory of the Fovea
Authors: Pumphrey R. J.
Published: April 2021

The structure and distribution of the two principal types of fovea are briefly described. Using the convexiclivate central fovea of the eagle as a type the effect of refraction at the boundary of retina and vitreous humour on the foveal image is computed. It is shown that, when aberration and diffraction are taken into account, no improvement in acuity can result from refraction at the fovea. On the contrary, the results strongly suggest that the convexiclivate fovea is a device for achieving improved fixation and improved sensitivity to movement of objects in the visual field at some sacrifice of acuity.

The application of these results to other variants of fovea is discussed, and a scheme indicating possible relations between function and geometrical form is proposed.
Some Observations on Water-Soluble Factors Which Accelerate the Growth in Aseptic Culture of Larvae of Drosophila Melanogaster
Authors: Begg M.
Published: April 2021

An effective technique is described for the aseptic culture of larvae of Drosophila melanogaster. Factors which accelerate the growth of Drosophila in aseptic culture on a basal medium containing casein as a source of amino acids can be extracted from both yeast and pancreas in water-soluble form. Part of the activity of such fractions can be removed by adsorption on anion exchange resins, or on charcoal; and eluted with ammonia. The whole activity is dialysable and recoverable from the dialysate by evaporation under reduced pressure. The active components are heat stable. The active fraction is insoluble in N-butanol, ethanol, acetone, pyridine and ether. Some evidence is presented for the presence of at least two components. The possibility that one of the factors may be a peptide is considered. It is thought unlikely that it is an amino acid.
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord
Published: April 2021

Sea-urchin spermatozoa {Echinus esculentus) are extremely sensitive to changes in the pH of the suspending medium, their respiration being proportional to pH between 7· 6 and 8· 4. In a manometric experiment in which semen was diluted 1·25 with sea water (CO2 absorbed), the pH of the suspension was 7· 5 at the beginning of the experiment and 8· 2 at the end, after 180 min. incubation at 150 C. Sea water, buffered with glycyl glycine, 0-025 M and brought to pH 8 3, was added to a sperm suspension whose pH was 7· 5 at the beginning of the experiment, after a period of incubation. There was a pronounced respiratory Dilution Effect. When the sea water was buffered with glycyl glycine and brought to pH 7·8, and this diluent was added to the same sperm suspension, there was a negligible respiratory Dilution Effect. The O2 uptake of suspensions prepared in buffered sea water at pH 8·3 was markedly higher than that in the same buffered sea water at pH 8-o. These observations cast doubt on the reality of the respiratory Dilution Effect when observed in experiments in which sea water is the suspending medium and respiration is measured by a method involving the absorption of CO2. An exception to this generalization was observed in buffered sea water at a low pH, 7 · 6. In this case, the O2 uptake of dilute suspensions was greater, per unit number of spermatozoa, than that of dense suspensions. 2,4-dinitrophenol, 6 × 10−5 M, stimulated the O2 uptake and depressed the motility of spermatozoa more in dense than in dilute suspensions. Versene, 10−3 M, reversed the action of 2,4-dinitrophenol. The results of other workers on adding suspensions of usnic acid to sea-urchin spermatozoa were not confirmed. This substance is more toxic to spermatozoa in dilute than in dense suspensions.
Glycogenolysis in the Liver of the Common Frog, Rana Temporaria
Authors: Tindal J. S.
Published: April 2021

The form of the temperature-glycogenolysis curve of frog’s fiver slices, when incubated with Ringer solution, was determined over the range 7-21° C. for samples of frogs over a period of 18 months. Three types of curve were observed: (a) Low linear, interpreted as being the least complex form, in which the action of temperature is not complicated by other factors.(b) Type B, which showed a disproportionate increase in glucose production above a certain temperature, attributed to the potentiation of sympathomimetic material.(c) High linear. Both the addition of adrenaline and noradrenaline to the incubation medium caused an increase in glucose production at all temperatures. Also, the dispropor-tionate increase in glucose production of the type B curve occurred at a lower temperature in the presence of either of these agents. Thyroxine had no effect on the form of the temperature-glycogenolysis curve, and there was no correlation between the state of activity of the thyroid gland and the type of temperature-glycogenolysis curve. Glucose production of Ever slices was lowered at all temperatures by the in vivo administration of insulin 19 hr. prior to an experiment. Insulin in vitro had no action. Dibenzyline lowered glucose production of Ever sEces at aU temperatures, and raised the temperature at which the extra glucose production, associated with a type B curve, occurred. The extrapolation of the lower portion of the mean curve after dibenzyline to 210 C. gave a line almost identical with the mean low linear curve. The environmental temperature at which frogs were maintained prior to an experiment did not affect the form of the temperature-glycogenolysis curve. The seasonal variation in Ever-glycogen content was found to agree closely with the values obtained by Smith (1950).
The Behaviour of Minnows (Phoxinus Phoxinus L.) in A Light Gradient
Authors: Woodhead P. M. J.
Published: April 2021

Minnows in a light gradient tank were almost constantly active, but were restricted in their movements by light above a certain intensity. The value of the limiting intensity differed for individual fish but lay between o·2 and 0·002 m.c. These values are of the same order as the threshold for light stimulation of the pineal complex in blind minnows, described by Scharrer. It is suggested that the pineal might be the receptor for the light limit, and evidence supporting this suggestion is discussed. Hungry minnows were not limited by light, and spent a considerable percentage of the observation time in the lightest parts of the tank. After feeding they assumed normal limited behaviour. In mid-April, prior to spawning, minnows examined in the gradient were extremely active and showed little sign of a light limit. The mean swimming speed of fish in mid-April was 159 % faster than that of fish observed in December.
The Behaviour of Minnows in Relation to Light Intensity
Authors: Harden Jones F. R.
Published: April 2021

Minnows kept in a tank are active during the day and quiet at night. Their behaviour is reversed if they are given hollow bricks in which they take cover and so avoid bright light. When cover is available they are very active at sunrise and sunset. Minnows have no inherent daily rhythm of locomotory activity. Blind minnows respond to daily variations in light intensity, and are more active at night than during the day. Minnows will not cross a light-dark boundary when the intensity on the light side is greater than 0.17-0.08 m.c A minnow shoal disperses between intensities of 0.024 and 0.0034 m.c. Minnows catch Dapknia better in bright light than in the dark. The change from visual to ‘dark’ feeding takes place between 0.0007 and 0.00007 m.c. Minnows appear to avoid bright light by a comparison of intensities if the light-dark boundary is sharp, but they may also respond to light photokinetically. It should be noted that these results, obtained in the laboratory, may not be true for minnows under natural conditions.
The Paradox of Mytilus Muscle. A New Interpretation
Authors: Hoyle G. , Lowy J.
Published: April 2021

The mechanism of contraction and relaxation in the anterior byssus retractor muscle (A.B.R.M.) of the lamellibranch mollusc Mytilus edulis has been studied with refined stimulating and recording techniques. Two distinct types of response are present: phasic and tonic. The former can be evoked by all kinds of electrical stimulation, but the latter is most readily elicited by continuous direct current. Serotonin (5-hydroxytryptamine) rapidly abolishes the tonic response, whilst leaving the phasic response practically unaffected for many hours. On electrical stimulation, a serotonin-treated muscle may show spontaneous electrical and mechanical activity, usually of a rhythmical nature. As the muscle is unable to destroy this drug the effects produced by it are likely to be of pharmacological interest only. Electrical activity in the form of irregular volleys of muscle action potentials can be recorded from the intact A.B.R.M. and even after the nerves to the muscle have been cut. In such (externally) denervated preparations the spontaneous electrical activity is almost unaffected by a.c. stimulation but greatly increased by d.c. stimulation which evokes prolonged tonic contraction. Stimulation of inhibitory nerves within the muscle quickly terminates a state of tonic contraction and at the same time reduces the electrical activity considerably. An explanation is offered for the occurrence of electrical activity during relaxation of lamellibranch smooth muscles. The normal functioning of the A.B.R.M.is interpreted, and strong support is given to the tetanus hypothesis of tonic contraction.
Proteolytic Activity of the Midgut in Relation to Feeding in the Beetles Tenebrio Molitor L. and Dytiscus Marginalis L.
Authors: Dadd R. H.
Published: April 2021

Where quantitative methods have been applied to the study of insect digestion, enzyme activity has generally been shown to increase after feeding, often with change in location of maximum enzyme concentration (Schlöttke, 1937 Or-c ; Duspiva, 1939; Day & Powning, 1949; Fisk & Shambaugh, 1952). The most marked responses described by these authors occur in carnivorous and blood-sucking insects, and to some extent this supports the view put forward on histological grounds by Haseman (1910), that discontinuous secretion is associated with the carnivorous habit of taking discrete meals.
Effects of Hypothermia and Hyperthermia on Fertilization in Rat Eggs
Authors: Austin C. R.
Published: April 2021

The chilling of rats to body temperatures down to 4-7° C. before and during the time of ovulation had little effect upon the subsequent penetration of the eggs by spermatozoa. With a hypothermia of 0-1° C, however, there was almost complete and apparently permanent inhibition of spermatozoon entry. There seemed to be no reason to ascribe this effect to direct influence of cold on eggs or spermatozoa. Probably the failure of penetration arose largely from delay of ovulation, coupled perhaps with some derangement of the tubal environment.

Hypothermia after ovulation but before and during the time of spermatozoon entry into the eggs temporarily but completely inhibited penetration when the body temperature was kept below 33° C. The likely explanation appears to be that ‘capacitation’ is prevented or greatly slowed by such temperatures.

Hyperthermia, induced before and during the time of ovulation, somewhat reduced the mean number of eggs ovulated (from 10.5 to 7.5) and the proportion penetrated by spermatozoa (from 97 to 66%). The proportion of eggs penetrated by two or more spermatozoa was increased (from 19 to 28%), but the frequency of polyspermic fertilization did not change significantly.

Hyperthermia after ovulation but before and during the time of spermatozoon entry also led to a greater proportion of eggs containing two or more spermatozoa (31%), but in addition it increased the incidence of polyspermy (from 2.5 to21.2%). Larger rats (170-200 g.) subjected to hyperthermia showed a higher frequency of polyspermy (34%) than smaller rats (100-130 g.; 13% polyspermy).

Evidently the processes involved in the ‘zona reaction’ are reduced in efficiency by hyperthermia whether applied before or after ovulation. On the other hand, the block to polyspermy depends on processes that are much more sensitive to heat after ovulation. It is considered that the slowing down of the block to polyspermy is associated with ageing of the egg, that the ageing is accelerated by hyperthermia and that this effect is promoted in older rats.
Pressure Receptors in the Fins of the Dogfish Scylliorhinus Canicula
Authors: Lowenstein Otto
Published: April 2021

The presence of so-called terminal corpuscles in the connective tissues of the fins of Scylliorhinuis canicula, first described by Wunderer in 1908, is confirmed. It is demonstrated that they are pressure receptors with a slow rate of adaptation. From their topographic distribution and from their mode of response to mechanical stimulation, it is postulated that the terminal corpuscles serve as proprioceptors in the widest sense of the term by signalling the spatio-temporal patterns of active or passive deformation of the fin. Their topographic distribution makes it possible to distinguish their responses from those of sense endings associated with the muscles or tendons of the fin.
The Interaction Between Metals and Chelating Agents in Mammalian Spermatozoa
Authors: White I. G.
Published: April 2021

Several studies have been made on the bacteriostatic and fungicidal properties of oxine (8-hydroxyquinoline) and other chelating agents, and it has been suggested that they might act, in part at least, by depriving cells of essential trace metals (Albert, 1951; Martell & Calvin, 1952).
Some Aspects of Osmotic Regulation in Lampreys
Authors: Hardisty M. W.
Published: April 2021

The mean osmolar concentration (expressed as mM. NaCl/l.) of the serum for Lampetra planeri was found to be no mM. in the ammocoete and 113 mM. in the adult. For adult L. fiuviatilis szerum in November the mean osmolar concentration was 143 mM. and in March 136 mM. In adult planeri the Cl concentration of the body fluids accounted for nearly 90% of the total concentration as compared with only 58% in the serum of the ammocoete. Adult fiuviatilis kept in tap water throughout the winter appeared to show an increase in Cl levels. Evidence has been produced to support the view that the differences observed in water, fat and Cl content of ammocoete and adult planeri and adult fiuviatilis are consequences of the period of starvation preceding sexual maturity. Pronounced seasonal variations have been found in the fat and Cl content of ammocoetes of planeri. The osmotic uptake of water has been determined for adults of both species in fresh water. In planeri the rate of uptake for unit body weight is about four times as great as in fiuviatilis. Observations have also been made on the osmotic loss of water of ammocoete and adult planeri and of adult fiuviatilis in sea water of different concentrations. For unit body weight osmotic loss of water in planeri is about twice that of fiuviatilis. Total losses of Cl have been determined for ammocoete and adult planeri in distilled water and their effects on internal Cl levels have been studied. Observations have also been made on the active uptake of Cl. Acclimatization experiments on ammocoetes and adult planeri and on adult fiuviatilis have failed to produce any evidence of regulation in sea water.
Control of the Melanophores of the Minnow (Phoxinus Phoxinus (L.))
Authors: Gray E. G.
Published: April 2021

The effects of sectioning the nerve fibres supplying a tail area of melanophores in the minnow under various experimental conditions were studied by a method of continuous observation employing visual and photomicrographic recordings. In the white-adapted fish, nerve section causes a band of melanophores to disperse. The initial dispersion later subsides, the band melanophores aggregating first at the band margins (primary fading). Subsequently the band melanophores react to background reversals in a similar way to normal ones. Hypophysectomy does not interfere with the initial dispersion or primary fading of band melanophores. Furthermore, these melanophores still react tobackground reversals, but in this case they react first at the margins of the band. Prolonged white-adaptation, favouring maximal activities of aggregating pituitary hormones, does not prevent the initial dispersion resulting from nerve section. Band melanophores with fibres sectioned 5 days previously react to diffusing aggregating neurohumours liberated by electrical stimulation. Melanophores with fibres newly sectioned remain dispersed, refractory to this aggregating agent. When the chromatic fibres at the level of the spinal cord are sectioned in a white-adapted fish with a faded tail band the normal melanophores disperse and later the band melanophores disperse first at the margins. A possible interpretation is that dispersing neurohumours are liberated by spinal section. Asymmetric responses of melanophores indicate that neurohumours can activate located regions of the individual melanophore. The mechanism of the melanophore dispersion resulting from nerve section is discussed together with the question of single or double innervation and the related activities of aggregating and dispersing neurohumours.
Endocrine Activity During Insect Embryogenesis. Control of Events in Development Following the Embryonic Moult (Locusta Migratoria and Locustana Pardalina, Orthoptera)
Authors: Jones Bryn M.
Published: April 2021

Secretory activity of the ventral head glands in embryos of Locustana pardalina and Locusta migratoria is necessary for inducing the moult and controlling subsequent events in late development. Continued secretory activity of the glands for a period after the moult is required for further progress in development. The development hormone released by the glands activates in turn the pleuropodial glands. The latter, in order to become fully functional, also require the continued secretory activity of the endocrine glands for a period after the moult. The enzyme-substrate system responsible for the formation of melanin does not become active until the development hormone is liberated. However, the system was present in the egg beforehand in an inactive state and it is suggested that it is held in check by an inhibiting influence. The amount of melanin deposited appears to be correlated with the amount of development hormone released.
The Effect of Temperature Upon the Permeability to Water of Arthropod Cuticles
Authors: Mead-Briggs A. R.
Published: April 2021

The effect of temperature alone upon the permeability of arthropod cuticles has been investigated by measuring the rate of transpiration into a constant saturation deficit at a number of temperatures. The permeability of the cuticles of Oniscus asellus and Lithobius sp. is little affected by temperature. The cuticles of Calliphora erythrocephala, Glossina palpalis, Blatta orientalis and Periplaneta americana become progressively more permeable as the temperature is raised from 30 to 50, or 55° C. That of Tenebrio molitor larvae behaves similarly, but the increase in permeability is less marked until the temperature rises above 40° C. The progressive increase in permeability of the cuticle of Periplaneta is entirely eliminated if the soft wax coating is removed. The increase in permeability of the insect cuticle with temperature is approximately exponential and cannot result from a single, abrupt change in a wax layer at a ‘critical temperature’. Possible physical bases for a continuous change are discussed.
Temperature Relations of Teneral Development and Behaviour in Aphis Fabae Scop
Authors: Taylor L. R.
Published: April 2021

The teneral stage in Aphis fabae Scop, is defined as the interval between eclosion of the alate imago and flight when flight is not extrinsically activated or inhibited. In field marking experiments the teneral stage is shown to be usually development-limited, not behaviour-limited, by its relationship to temperature. It is suggested that the logistic curve fits the rising temperature × development-velocity curve because this is a statistical distribution like the Pearson type 1. The logistic curve is fitted to teneral period in naturally varying temperatures by a method of successive approximation. In trapping experiments take-off is inhibited by light below c. 100 f.c. and by temperature below c. 16° C. at 1 ft. in a bean crop. These behaviour responses sometimes lengthen the apparent teneral period. The results are confirmed in the laboratory at constant and at varying temperatures. This also confirms that temperature changes per se even over a range of c. 7-34° C., and other climatic factors, have negligible effect on rate of development during the teneral period. Individual variation is a constant proportion of teneral time at all temperatures. In laboratory experiments the same criteria apply to Aglais urticae L. This period of inactivity warrants further examination in an ecological context.
Spectral Sensitivity of Chromatophores in Diadema Setosum (Leske)*
Authors: Yoshida Masao
Published: April 2021

Classical accounts of the effect of coloured light on retinal pigment migration in frogs and crayfish have been reviewed by Parker (1932). Most of those results agree in indicating violet or blue as the most effective light. Zetter (1956) has shown that the light of wavelengths near to 540 m/x is most effective for the expansion of melanophores in frog’s skin. On the other hand, the direct effect of light upon the iris, which responds like melanophores, shows that 486 mμ is the most effective wavelength (Weale, 1956).
Rotation Experiments with Blind Goldfish
Authors: Jones F. R. Harden
Published: April 2021

Blind goldfish react to rotation at constant angular velocity by swimming against the direction of rotation so as to maintain, on the whole, the same orientation or bearing relative to earth. The lowest angular velocity to which the fish appear to react is below 10°/sec. For the best performers the threshold is about 3°/sec. The stimulus to which the fish responds is not one of contact, initial swirl or water current (when the turntable gets under way), variation in turntable velocity or centrifugal force. The semicircular canals are probably the sensory channels through which a fish is able to detect rotation at constant velocity and the mechanical stimulus to which it responds is probably an angular acceleration. How the fish becomes aware of angular accelerations during rotation at constant velocity is not yet understood.
Amino-Acid Metabolism in Locust Tissues
Authors: Kilby B. A. , Neville Elisabeth
Published: April 2021

Homogenates of fat-body of Schistocerca gregaria Forsk. were shown to catalyse transamination reactions between α-ketoglutarate and. numerous α-amino acids. The aspartate/glutamate and alanine/ghitamate transaminases were the most active. They were present in both the ‘soluble ‘and the mitochondrial fractions of fat-body cells and also in Malpighian tubules and mid-gut wall. The other transaminases in the fat-body were confined to the mitochondrial fraction. Fat-body, Malpighian tubule and mid-gut wall homogenates were able to convert glutamic acid into glutamine, a compound which could also act as an amino-group donor in some transamination reactions. A glutamate-cytochrome c reductase system which involved diphosphopyridine nucleotide was present in fat-body. Fat-body contained an active arginase, but urease could not be detected. A D-amino-acid oxidase was present, together with a less active L-amino-acid oxidase. In general, it appears that amino-acid metabolism in the locust resembles that in higher animals.
Repeated Presentation Experiments and the Function of the Vertical Lobe in Octopus
Authors: Wells M. J. , Wells J.
Published: April 2021

When presented with a small object that it has not previously encountered, an octopus passes the object to its mouth and attempts to eat it. Inedible objects are rejected after a period of minutes, and when the same object is repeatedly presented at short intervals, the animal rapidly learns to examine and reject it without passing it to the mouth. That the animal is learning to recognize a particular object and not merely becoming fatigued or generally less reactive can be demonstrated by changing the object; a new object is almost always taken, even if the animal has not taken the original for many trials. After a break in training of the order of hours, the animal may accept the same object when it is presented again, but relearns not to take it in fewer trials than in the original training. The performance of two animals tested after removal of the optic lobes was in all respects comparable to that of three controls (two unoperated and one with the optic nerves cut). Six animals with the vertical lobe of the brain removed were also tested. The performance of these animals differed from that of five controls in two respects: they took six times as long to examine and reject the objects in the first trial, and they showed relatively poor retention following breaks in training. The first of these differences is particularly important because it shows that removal of the vertical lobe has effects other than increasing the rate of fading of memories between trials. The significance of this in the interpretation of the function of the vertical lobe from discrimination experiments is discussed.
Studies on the Influence of the Embryonic Environment on the Post-Hatching Development of Chickens
Authors: Ryle Margaret
Published: April 2021

Techniques are described for removing and replacing approximately 15% of the total volume of yolk after 5 days’ incubation, or of albumen after 2-3 days’, in hens’ eggs. These allow up to 50 and 40% respectively of the eggs to hatch. Yolk and albumen were exchanged between different breeds of chickens, and chicken eggs received yolk and albumen from other species. Embryonic viability was not reduced by egg constituents of other breeds or species. Small numbers of chickens from eggs which received turkey, goose and duck yolk, and larger numbers from eggs which received turkey albumen, were hatched and reared successfully; they appeared to be quite normal. Legbar eggs received yolk from Polish Bantam eggs. The experimental birds weighed significantly less than their control siblings at 139 days. The mean shank lengths were not significantly different. Attempts to repeat the experiment failed to support this result ; possible reasons for this are discussed. Polish Bantam eggs received yolk from Dorbar eggs. At 100 days they were significantly heavier than their control siblings, but their mean shank lengths were almost identical. In each of the four 1955 albumen exchange experiments the mean weight of the experimental birds at 170 days was greater than that of their control siblings, but not significantly so. On pooling the data a significant difference was found at 100 and 114 days (P=0-05) and 170 days (P<0·02). The mean shank lengths were very similar. The 1956 experiments failed to confirm these results; possible reasons for this are discussed. It appears that, in certain circumstances, exposure of the embryo to ‘foreign’ yolk or albumen may influence post-hatching growth in weight, but this effect is only detectable when the chicks are over 3 months old.
Flight Activity in the Blowfly Calliphora Erythrocephala, in Relation to Light and Radiant Heat, With Special Reference to Adaptation
Authors: Digby Peter S. B.
Published: April 2021

The spontaneous flight activity of a population of the blowfly Calliphora erythrocephala has been studied in relation to light and radiant heat in a small wind tunnel. Flight activity occurs at a low level in the dark under these conditions, and is practically independent of light up to 10 lux. Activity increases sharply with light between 10 and 2600 lux, before heating effects become important. Population activity shows adaptation to light intensity, and a method of analysis is described. The rate of increase of activity following an increase of light is much slower than is the reverse change; the state of low activity at low light intensities tends to persist. Complete adaptation would take at least a number of hours. Heating, which accompanies strong light intensities, causes initially a momentary decrease in activity, usually followed by an increase. Similar reactions occur when the heat is applied in several different ways."
The Speed of Swimming of Fish as Related to Size and to the Frequency and Amplitude of the Tail Beat
Authors: Bainbridge Richard
Published: April 2021

An apparatus is described in which it is possible to study and record the continuous swimming of fish at speeds up to 20 m.p.h. Records made of the swimming at different speeds of dace, trout and goldfish measuring up to 30 cm. in length are reproduced. Speed at any particular frequency of tail beat is shown to be directly related to the length of the specimen, measured from the tip of the snout to the most posterior extremity of the tail. Above a frequency of 5 tail beats per second speed is directly dependent upon frequency up to the maximum values recorded. The results for all sizes and species recorded may be adequately expressed by the formula , where V is the speed in cm. per sec., f is the frequency in beats per sec. and L is the body length in cm. The distance travelled per beat (and hence the speed) is directly dependent upon the amplitude of the tail beat. The amplitude increases with increasing frequency up to a maximum reached at about 5 beats per second. This maximum amplitude is the same for all fish tested and is about one-fifth of the body length. The maximum frequency attainable decreases with increasing size of the specimen. This decrease is slight in the trout and more pronounced in the dace and goldfish. Estimation of the possible maximum frequencies of much bigger fish allows for prediction of the maximum speeds they may be able to attain. Such predicted speeds are in accord with the few measurements that have been made and are of the order of 10 body lengths per second up to a size of 1 m.
The Survival of Artemia Salina (L.) in Various Media
Authors: Croghan P. C.
Published: April 2021

The survival of Artemia salina adults in various media has been studied. Prolonged survival is only possible in media in which certain sodium salts (principally NaCl) predominate. Certain substances are found to be highly toxic. It is confirmed that the high toxicity of potassium ions can be antagonized by sodium ions. The results indicate that the animal is appreciably permeable.
The Osmotic and Ionic Regulation of Artemia Salina (L.)
Authors: Croghan P. C.
Published: April 2021

It has been possible to adapt Artemia to sea-water media varying from 0·26% NaCl to crystallizing brine. In fresh water or distilled water survival is relatively short. The osmotic pressure of the haemolymph is relatively independent of the medium and increases only slightly as the medium is made more concentrated. In the more concentrated media the haemolymph is very markedly hypotonic. In media more dilute than 25 % sea water the haemolymph is hypertonic. In distilled water there is a rapid fall of haemolymph concentration. The haemolymph of nauplii from sea water is hypotonic. The sodium, potassium, magnesium, and chloride concentrations of the haemolymph have been determined. The bulk of the haemolymph osmotic pressure is accounted for by sodium and chloride ions. The ionic ratios of the haemolymph are relatively constant, and very different from those of the medium. The concentrations of ions in the whole animal have been studied. The chloride space is extremely high. Such changes in haemolymph osmotic pressure that do occur as the medium concentration is varied are due more to net movements of NaCl into or out of the body than to water movements. Evidence is collected to show that an appreciable degree of permeability exists. Most of this permeability is localized to the gut epithelium, the external surface being much less permeable. It is clear that Artemia must possess mechanisms that can actively excrete NaCl and take up water in hypertonic media. It has been demonstrated that Artemia can lower the haemolymph osmotic pressure by excreting NaCl from the haemolymph against the concentration gradient.
The Movement of the Spermatozoa of the Bull
Authors: Gray J.
Published: April 2021

The rate at which the spermatozoa of a sea-urchin propel themselves can be expressed, with surprising accuracy, in terms of the form and frequency of the bending waves generated by the tail (Gray, 1955; Gray & Hancock, 1955). The object of this paper is to consider how far this conclusion is applicable to other types of flagellated spermatozoa; those of the bull with their relatively larger heads and thicker tails provide a useful basis of comparison and contrast.