bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Experimental Investigation of Navigation in Homing Pigeons
Authors: Matthews G. V. T. 
Published: April 2021

ABSTRACT
A series of field experiments were carried out in 1948, 1949 and 1950 to establish the facts of navigation in homing pigeons and to begin an investigation of the factors involved. A total of 158 pigeons aged 3–4 months were used in twenty-three tests involving a total of 902 sorties, all but 153 being by birds released singly. Three indices of performance were used, giving the degree of uncertainty on release, the accuracy of the initial course and the success in regaining home. It was shown that pigeons are able to fly in one particular direction when released at a series of unknown points at increasing distances north-north-west of the loft. The following of experienced birds or the use of distant landmarks were excluded. Overcast skies had a disorientating effect on these training-line releases. It was shown that if the sun was being used to determine the training direction, it was not by any simple fixed-angle relationship to home. The birds could take large Changes of azimuth into account, and at least ignore changes in altitude, without having witnessed the sun’s movement. Releases were also carried out in unknown areas at right angles to or in the opposite direction from the training line. Some of the birds flew in the training direction and homed badly. But a good proportion showed a definite orientation in the home direction and returned with fair success. This true navigational ability was shown to vary widely amongst individual pigeons. The proportion of able navigators also varied in different stocks. There is little evidence of a continuous maturation of the faculty with experience and none with age. There are suggestions that it is not connected with a learning process. The established facts require more than a random or systematic search for landmarks, or the use of atmospheric clues as an explanation. It is shown by experiment that pigeons do not depend on the interpretation of the earth’s magnetic field to be able to orientate in the training or in the home direction. Other experiments show that a displacement recording mechanism based on time/acceleration measurements is extremely unlikely. The only positive lead obtained is a definite suggestion that overcast had a disorientating effect on pigeons released off the training line. This requires detailed confirmation. The simplest way in which a pigeon could obtain a rough estimate of its position relative to home by measuring the sun’s co-ordinates is considered. Attempts to follow individual pigeons or groups of three by aircraft have so far been unsuccessful. An automatic flight recorder has been used successfully to some extent.
Fragmentation of Red Cell Ghosts in Relation to the Problem of Red Cell Structure
Authors: Ponder Eric 
Published: April 2021

ABSTRACT
An indication as to whether a body is a solid or a hollow shell can be obtained by dividing it into a number of fragments and seeing whether the total volume of the fragments is substantially the same as, or smaller than, the initial volume of the body. If the former is the case, the indication is that the body is a solid, and if the latter is the case, the indication is that the body is a hollow shell. This test can be applied to the human red cell and to the human red cell ghost by heating them to temperatures between 49 and 54° C., a treatment which produces fragmentation into large enough fragments to be counted and to be thrown down by centrifuging, always provided that the cells and ghosts are discoidal (Ponder 1950a).
The Phases of the Oestrous Cycle in the Adult White Rat
Authors: Mandl Anita M. 
Published: April 2021

ABSTRACT
Since the classical description of Long & Evans (1922) of the cyclical changes which take place in the vaginal smear of the rat, vaginal smea histology has always been used as an index of ovarian activity. It is also used as a test of the potency of various steroid hormones (e.g. Emmens, 1939), and as a means of correlating cyclical ovarian changes with those in the accessory reproductive organs and other endocrine organs (e.g. Astwood, 1939; Bourne & Zuckerman, 1940). Numerous studies have been made of the cytology of shed vaginal cells by means of trichrome stains (e.g. Hartman, 1944), and various modifications have been suggested for the original technique proposed for taking vaginal smears.
Under normal laboratory conditions it is inconvenient to take smears more than once a day. At the same time it is known that frequent smearing may itself induce cornification (Astwood, 1939). In view of the need to time various operative procedures accurately in relation to the phases of the oestrous cycle, the following study was undertaken (a) to determine the individual variability of cycle length in our own colony of rats and (b) to compare our data with those reported for other laboratories.
Cyclical Changes in the Vaginal Smear of Adult Ovariectomized Rats
Authors: Mandl Anita M. 
Published: April 2021

ABSTRACT
According to Kostitch & Telébakovitch (1929), cyclical changes continue to occur in the vaginal smear of rats after removal of both ovaries. The following study was undertaken because of the important bearing this observation has on an understanding of the rhythmical changes which occur in the accessory reproductive organs, and because no reports of its confirmation have appeared in the literature.
Fermentation in the Rumen of the Sheep
Authors: Gray F. V. , Pilgrim A. F. , Rodda H. J. , Weller R. A. 
Published: April 2021

ABSTRACTEarly workers in the field of ruminant physiology were aware of the presence of formic, acetic, propionic and butyric acids (Tappeiner, 1884), and of smaller amounts of higher members of the saturated fatty acid series (Mangold, 1934), in the rumen fluid. Accurate data were not reported, however, until recently, when partition chromatography became available as an analytical procedure for the analysis of complex mixtures of these acids (Elsden, 1946). By this means acetic, propionic and butyric acids were established as the main components of the mixture of fatty acids in the rumen fluid of sheep and of other ruminants. The butyric acid fraction, however, was thought to contain some higher acid or acids, and it was claimed that formic acid was not a component of the mixture (Elsden, 1945). Using modifications of the older partition and distillation methods Gray (1946) found similar proportions of the three main acids, but also stated that small amounts of formic acid were normally present.
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord , Cleland K. W. 
Published: April 2021

ABSTRACT
Sea-urchin spermatozoa (Echinus esculentus) contain 4·14 mg. phospholipid per 1010 spermatozoa (arithmetic mean of five replicated experiments, standard error 0·06). This amount of phospholipid is about 5·5 % of the dry weight of a seaurchin spermatozoon. The seminal plasma contains very small quantities of phospholipid, about 20 mg./100 ml., less than one-thirtieth the content of fresh semen. When sea-urchin semen was diluted 1:20 with sea water and the spermatozoa incubated aerobically for some 7 hr. at 20° C., phospholipid disappeared. The average disappearance per 1010 spermatozoa was 19·0% (S.E. 2·4), while the corresponding oxygen uptake of the same sperm suspensions during the same time was 1·450 ml. (S.E. o·118). The oxidation of glycogen or glycogen-like material was found to be entirely insufficient to account for the observed oxygen consumption. Assuming that the combustion of 1 mg. phospholipid requires 1·6 ml. oxygen, the ratio of the theoretical oxygen uptake (associated with the observed disappearance of phospholipid) to the observed oxygen uptake was 0·86 (S.E. 0·04). It is concluded that the oxidative breakdown of phospholipid, located in the middle-piece, is the principal source of the energy required for movement.
The Effect of Pituitrin on Fluid Distribution in Bufo Regularis Reuss
Authors: Ewer R. F. 
Published: April 2021

ABSTRACT
A new response to injection of posterior pituitary extract in Bufo regularis Reuss is described. If the animals are kept out of water after injection there is a significant increase in the fluid held in the lymph spaces, and fluid is resorbed from the bladder.
The accumulation of lymph is not accompanied by any significant decrease in the water content of the tissues.
The possible biological significance of the response is indicated.
Retinomotor and Diurnal Rhythm in Crustaceans
Authors: Henkes H. E. 
Published: April 2021

ABSTRACT
The demonstration of the existence of a diurnal rhythm in the migration of the pigment in Leander, Portunus, Pachygrapsus and Carcinus justifies the supposition that in many species of Crustaceans such a rhythm exists in the retinomotor changes of one of the pigment systems.
These periodic changes in the position of the pigment, despite the exclusion of all light, correspond with sunrise and sunset. Even if the animal is kept in complete darkness during the hours of daytime, the pigment systems concerned exhibit a partial migration towards the position of light-adaptation; when the night returns the pigment system resumes its maximum state of dark-adaptation and is found in the same position as in the previous night.
The measurement of the size of the pseudo-pupil is of value in proving, in vivo, the existence of a diurnal rhythm in the iris pigment. The existence of a periodic change in the luminosity of the living eye when examined with the ophthalmoscope is of no value in ascertaining the occurrence of a diurnal rhythm in the retinal pigment or in the tapetum.
In C. maenas it was possible to demonstrate a periodic variation in metabolism, in terms of a diurnal rhythm in the production of carbon dioxide. This production was about 30 % smaller during the day than during the night.
The diurnal retinomotor rhythm may depend on a periodic hypoxaemia of the cell systems concerned.
The Response Of A Sense Organ To A Harmonic Stimulus
Authors: Pringle J. W. S. , Wilson V. J. 
Published: April 2021

ABSTRACTThe response is described of the tactile ending in a femoral spine of the leg of Periplaneta to a harmonic (sinusoidal) mechanical stimulus of low frequency. The peak frequency of impulses in the sensory nerve precedes the maximum tension of the stimulus. This result is shown to be a corollary of the adaptation shown by the sensory response to a transient stimulus. The concept of the ‘transfer function’ is discussed in relation to neurophysiology. Its value is explained as a means of describing the dynamic properties of component parts of the nervous system when the objective is an understanding of the functioning of the complete rçflex arc.
The Co-Ordination of Insect Movements
Authors: Hughes G. M. 
Published: April 2021

ABSTRACT
Though walking forms part of many insect behaviour patterns, the mechanism of insect walking has received relatively little attention in recent years. As a preliminary to a later investigation of neuromuscular co-ordination in insects, the normal pattern of walking movements in the cockroach and other insects has been studied. The results obtained and an account of the functional anatomy of the insect leg are given in this paper. The forces involved have not been measured, but a preliminary analysis of the mechanics of walking has been made with the help of ‘stills’ from cinematographic films. The use of cinematography greatly facilitates such an investigation.
The Metabolism of the Sea-Urchin Egg
Authors: Cleland K. W. , Rothschild Lord 
Published: April 2021

ABSTRACT
The eggs of Echinus esculentus contain about 1·5% glycogen and 20% lipid (dry weight). Whole eggs produce lactic acid under anaerobic conditions, the maximum rate of production being 0·15 μl. lactate/hr./mg. eggs (dry weight) at 20° C. Lactic acid production is inhibited by fluoride, iodoacetate and phenylmercuric nitrate. The supernatant from centrifuged egg homogenates prepared in M/50-phos-phate buffer, pH 7° 5, (‘extract’), was found to be a satisfactory glycolytic enzyme preparation. The production of lactic and pyruvic acid by such extracts is greatly stimulated by the addition of glycogen, cozymase and adenosine triphosphate, (‘complemented extracts’). Complemented extracts glycolyse glucose and fructose with greater facility than glycogen or starch. With glucose or fructose as substrate, the rate of formation of lactate and pyruvate may reach 1° 7μd./hr./mg. eggs (dry weight) at 20° C. Complemented extract glycolysis is inhibited by fluoride, iodoacetate, phenylmercuric nitrate and phloridzin. Active extract glycolysis occurs with the following glycolytic intermediates as substrates: glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate, hexose diphosphate and phosphoglyceric acid. It is concluded that the sea-urchin egg (E. esculentus) possesses a typical glycolytic system, whose activity is comparable with that found in other invertebrate tissues.
The Responses of the Honey-Bee to Repellent Chemicals
Authors: Jones G. D. Glynne 
Published: April 2021

ABSTRACT
This paper is concerned, first, with the development of a technique for maintaining a population of honey-bees (Apis mellifera) under conditions where it does not have access to naturally secreted nectar, but is allowed free flying conditions, and secondly with the application of this technique to the study of the chemotropic responses of bees to repellent chemicals. Two types of stimuli are considered: (a) The effect of the addition of the repellent to an attractant (sucrose solution). (b) The effect of the repellent in the vapour phase in the vicinity of the attractant. In (a) techniques are described for measuring the response with the standard attractant alternating in time and space. Data collected on the rejection thresholds of acetic acid and phenol showed that whilst little variation in response occurred at the higher concentrations of the repellent, the offering of the standard attractant alternating in time as opposed to space greatly modified the response. Tests were carried out to determine the reproducibility of the results. It would appear that for a repellent chemical to be capable of effectively reducing the number of visits to a source of food, it must be capable of irritating the common chemical senses of the bee.
Differential Effects of Direct Current on Insect Ganglia
Authors: Hughes G. M. 
Published: April 2021

ABSTRACT
The passage of small direct currents transversely through the intact thoracic ganglia of the cockroach affects the flexor-extensor balance of the legs in such a way that the leg on the negative side flexes while that on the positive side extends. With longitudinal stimulation, ascending currents bring about flexion of both legs and descending currents encourage extension. Preparations in which only a single nerve is attached to the ganglion do not show these differential effects when the polarizing current is applied between ganglion and nerve. The negative electrode excites when it is on the ganglion, and the positive inhibits irrespective of whether the nerve supplies flexor or extensor muscles. Intermittent discharge of impulses may occur before the spontaneous discharge is completely inhibited when the positive electrode is on the ganglion. At least three different responses have been recorded from some of the leg muscles under these conditions and they are excited in a ‘functional order’. That is, the ‘slow’ response accompanied by a tonic contraction occurs at a lower threshold than the ‘faster ‘twitch systems. A hypothesis is put forward to interpret these apparently contradictory results. It is suggested that the polarizing current influences the gradient of potential along oriented intemuncials which are stimulated at low threshold in the intact preparation. These intemuncials connect regions of the neuropile containing flexor and extensor synaptic endings.
The Morphology of Bull Spermatozoa
Authors: Hancock J. L. 
Published: April 2021

ABSTRACT
The microscopical features of living and dead bull spermatozoa are described. The findings are discussed in. relation to previous observations on the structure of the head of the bull spermatozoon. The cytoplasmic cap of the living cell possesses a characteristic structure which is identical with that which has been ascribed to the acrosome. The altered structure of the cap of the dead spermatozoon is identical with that previously described as characteristic of a second cap-like structure, the galea capitis. It is concluded that the terms galea capitis and acrosome have been used to describe the same structure. It is suggested that the cytoplasmic cap of the bull spermatozoon should be called the acrosome.
On The Existence of Regionally Specific Evocators
Authors: Waddington C. H. 
Published: April 2021

ABSTRACT
Spemann (1931) pointed out that different parts of the organization centre in the amphibian gastrula have different properties, in that the more anterior regions tend, other things being equal, to induce the formation of more anterior parts of the neural system, such as the brain and associated sense organs, while the posterior parts tend to induce the neural tube of the trunk or tail. Living organizer grafts frequently become more or less fused with the induced tissues, so that if a definite organ is finally produced, the individuation of it involves both inducing and induced materials, the former playing the leading part. When dead pieces of the organizer are used as grafts, they cannot be similarly incorporated, and any individuation which may occur must have arisen entirely within the reacting material. It might still be possible, however, that the dead organizer was able to specify which region of the embryonic axis was represented by the induction, and thus guide the individuating processes. It has been known, however, since the work of Holtfreter (1934a) that organizer material after being killed loses its power to induce mesodermal tissues. It evocates only the appearance of neural tissue. If this becomes individuated into any recognizable organ, it is usually found to represent some region of the brain or eye, while the organs resulting from secondary inductive effects of the brain (e.g. nose or ear) are also frequently found. It is certainly not impossible to find a dead material which can induce more posterior regions of the axis, since Holtfreter (1934b), Chuang (1938) and Toivonen (1949, 1950) have demonstrated such activity on the part of dead adult tissues or extracts from them. No phenomena of the kind have, however, been described as resulting from the action of dead parts of the gastrula organizer, and it has been usual to consider that this material loses its trunk-inducing powers, and becomes solely a specific head-organizer, when killed.
The Thoracic Gland in Rhodnius Prolixus (Hemiptera) and Its Role in Moulting
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
It is now generally accepted that the periodic phases of growth in insects, which terminate in the deposition of a new cuticle and the casting of the old skin, are initiated by chemical changes in the circulating blood. For these growth-stimulating factors the general term ‘moulting hormone’ has been used (Wigglesworth, 1934), although it has been realized for some time that this hormone ‘might ultimately prove to be made up of more than one constituent’ (Wigglesworth, 1940) and that a succession of secretions might in fact be concerned (Williams, 1947; Wigglesworth, 1949).
Anal and Oral Intake of Water by Crustacea
Authors: Fox H. Munro 
Published: April 2021

ABSTRACT
In small and transparent Crustacea water can be seen with a microscope to be pumped through the anus into the intestine. The pumping is done by antiperistaltic contractions of rectal muscles, the movements being repeated rhythmically at intervals of one to a few seconds. They may continue almost without interruption or may occur for short periods with intervals of rest. In some genera the entrance of water by successive gulps is quite clear; this is the case, for example, in Triops, Sida, Diaphanosoma, Leptodora, Mysis, Sphaeroma, Ligia, Corophium. In other genera, such as Artemia, Chirocephalus, Limnadia and Bythotrephes, it is not obvious that water enters, although waves of contraction are seen to pass inwards over the rectal musculature. In Daphnia the gulps cannot be seen when the antiperistalsis is slow, but they are clearly visible when it is rapid.
The Toxicity of Potassium Cyanide to Trout
Authors: Herbert D. W. M. , Merkens J. C. 
Published: April 2021

ABSTRACT
An apparatus is described in which fifty yearling rainbow trout can be tested in a stream of water at a constant temperature and containing a constant concentration of poison. Exposure to cyanide causes the fish to lose equilibrium control and to turn over. Resistance is measured as survival time, by which is meant the time taken to overturn the fish. When the experimental temperature is higher than that of the water in the stock aquaria the resistance of yearling rainbow trout to cyanide increases with increasing time of acclimatization to the temperature of the experiment. Small yearling rainbow trout tend to be more resistant to cyanide than larger fish of the same age. The distribution of the logarithms of the survival times of the test fish in cyanide solutions, though not precisely normal, is sufficiently close to a normal distribution to justify the application of standard statistical techniques. Neither the distribution of the survival times nor that of the reciprocals of the times provide a suitable basis. At 17·5°C. in the range 2·5 parts to 0·07 part CN per million it has been found that (i) mean log survival time decreases linearly with log concentration, (ii) the variance of log survival time is approximately constant, and (iii) the distribution of log survival time is approximately normal. At higher concentrations these conclusions are not true. The resistance of an individual rainbow trout to cyanide is mainly determined by inherent properties which persist for at least three weeks.
Studies in the Development of the Rainbow Trout (Salmo Irideus)
Authors: Smith Sydney 
Published: April 2021

ABSTRACT
The total carbohydrate content of the trout egg and embryo has been measured. The carbohydrate content falls during three periods: (i) the establishment of the blood circulation; (ii) hatching; and (iii) the onset of starvation. The fats extracted by a non-polar solvent (carbon tetrachloride) from egg, embryo and yolk samples show no significant catabolism before hatching. These fats are considered to be glyceride-fats. In the yolk-sac stage such fats are only consumed between the 63rd and 80th days of incubation at 10° C. The combustion of phosphatide fat deduced from the heat-production figures is conspicuous during the early stages of yolk-sac absorption, and may be correlated with the consumption of protein as an energy source. These findings may be correlated with histological changes in the yolk-sac wall, and in the relation between yolk-sac and liver. The concept of a sequence of energy sources in ontogenesis is discussed.