bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Relation Between the Development of the Secondary Sex Characters and the Structure of the Testis in the Teleost Xiphophorus Helleri Heckel
Authors: van Oordt G. J. 
Published: April 2021

ABSTRACT
The aim of this study was to trace the relation between the development of the secondary sex characters and the structure of the testis in the Cyprinodont fish Xiphophorus Helleri Heckel.
The secondary sex characters of both male and female are described. Only the development of the most conspicuous sex characters, viz., the gonopod, i.e., the anal fin transformed into an intromittent organ, and the sword, i.e., the enormously elongated ventral part of the caudal fin is considered in relation to spermatogenesis. These secondary sex characters are formed in the young male and are present throughout further life.
The testis of the young immature male in which the secondary sex characters have not yet developed, contains only a small number of primary spermatogonia besides many tubules derived from the peritoneal epithelium. Simultaneously with the beginning of the transformation of the anal fin into an intromittent organ spermatogenesis starts, and at the same time the epithelium of these tubules transforms into germ cells, being situated in small cysts. When the spermatogenesis has reached the formation of spermatocytes the elongation of the caudal fin has generally started.
The testis of the male in which the gonopod is fully developed, but of which the sword has not reached its maximum length, contains all stages of spermatogenesis up to spermatophores, but the latter are still found in the cysts. In the fully mature male the spermatophores are lying in great numbers in the sperm ducts. The question as to the seat of the secretion of the sex hormones in the sex gland is discussed briefly. It appears that it is improbable that there is in the gonad a group of cells, being the specific source of the sex hormones.
Studies in the Parthenogenesis and Sexuality of Saw-Flies (Tenthredinidæ)
Authors: Peacock A. D. 
Published: April 2021

ABSTRACT
After four years’ experimental work on parthenogenesis in saw-flies, the writer proposes to recount certain of the results in a series of papers under the above general title, and in doing so is desirous of designating as the first study of the series a former contribution to this Journal (Peacock, 1924). Hence, although this is the first time the general title has been used, the following paper is really the second study.
The Energy-Sources in Ontogenesis
Authors: Needham Joseph 
Published: April 2021

ABSTRACTThe class of compounds used by the developing embryo for the extraction of energy from its environment raises one of the most important questions which arises in the biochemical analysis of embryological phenomena. Does it behave exactly like the adult animal from the very beginning, or does it pass through phases each of which are, in this respect, different? To be able to compile a chart showing the compounds which the developing embryo utilises as energy-sources throughout its ontogenesis, to know the times and periods in which one supersedes another, would be to possess clues of enormous importance for the unravelling of every event in embryonic metabolism.
A Retardation in the Rate of Metamorphosis of the Colorado Axolotl by Injection of Anterior Hypophyseal Fluid
Authors: Smith Philip E. 
Published: April 2021

ABSTRACTIn 1922, the author with I. P. Smith, reported in a brief abstract that the intraperitoneal injection of fresh anterior hypophyseal fluid slowed decisively the environmentally-produced metamorphosis of the Colorado axolotl (A. tigrinum). In a second abstract (Smith and Smith, 1923), it was shown that the injection of fresh anterior lobe fluid also diminished the metamorphic stimulus afforded by thyroid administration.Since the appearance of these abstracts, Hogben (1923) has reported opposite effects, namely, that the intraperitoneal injection of a commercial anterior lobe extract caused a rapid metamorphosis of the normal unoperated Mexican axolotl (A. tigrinum) and even of thyroidectomized individuals of this species. Spaul (1924 a), using the same commercial preparation as Hogben, confirmed the results of this investigator in the unoperated axolotl and found in addition that the metamorphic rate of the tadpole was greatly accelerated. More recently, Spaul (1924 b) tested some twelve commercial anterior pituitary preparations for the presence or absence of a principle which would metamorphose the axolotl. He found that only two of these produced what he terms “the appropriate response,” namely, metamorphosis ; the other ten gave negative results. He assumed that these ten preparations contained some inhibitory substance which prevented the principle inducing metamorphosis from expressing itself. The opposite assumption might seem as reasonable, namely, that the ten preparations, because of their great numerical majority, gave “the appropriate response,” and that the two preparations inducing metamorphosis contained some unusual substance giving an atypical response.
The Influence of Temperature and Moisture on the Uptake and Loss of Water in the Eggs of Gryllulus Commodus Walker (Orthoptera—Gryllidae)
Authors: Browning T. O. 
Published: April 2021

ABSTRACT
Eggs placed on moist plaster took up water slowly at first and then more rapidly until they had reached their maximum water content. The duration of the initial period of slow water uptake was dependent upon temperature, becoming shorter as the temperature was raised. Similarly the duration of the period of rapid water uptake decreased with temperature. No special water-absorbing structure was identified in the eggs of Gryllulus. The rate of water loss from newly laid eggs was more rapid at higher than at lower temperatures under conditions of constant atmospheric saturation deficiency. Newly laid eggs died if they lost more than about 20 % of their original weight. At 90 % relative humidity, eggs which had completed water uptake lost water at a higher rate at high than at lower temperatures. The rate of water loss was also dependent on the stage of development of the embryo. Eggs that had completed diapause development at 13° C. and had completed water uptake were able to lose about 30 % of their weight through desiccation without being killed, but many of those that lost more than about 20 % of their weight failed to develop when replaced on moist plaster; it seemed as if they had entered a state resembling diapause.
Some Aspects of the Mechanics of Mammalian Locomotion
Authors: Barclay Oliver R. 
Published: April 2021

ABSTRACT
Gray (1944) analysed the pattern of muscular activity in mammals, but there is practically no published experimental data which could be used to check this analysis. Elftman (1938, 1939a, b, c) working with man, and Manter (1938), working with the cat, developed various types of apparatus for recording the forces exerted on the ground, but Manter’s published results give adequate data for the calculation of patterns of muscular activity for a single stride only. Following similar work on the Amphibia (Barclay, 1946), an attempt was therefore made to record the forces exerted on the ground by various mammals and to obtain synchronous photographs of the limb positions with a view to calculating the activity in the main groups of limb muscles.
Potassium Ions and Insect Nerve Muscle
Authors: Hoyle G. 
Published: April 2021

ABSTRACT
The ionic composition of the blood of insects, unlike that of vertebrates and most other invertebrates, shows a wide range of values, especially in regard to the physiologically important ions of sodium and potassium. Preparations are described in which the effect of potassium on the active nerve and muscle properties of Locusta migratoria have been investigated. The nerve axons are depolarized by high concentrations of potassium ions in the same way as vertebrate and crustacean axons. The whole nervous system is surrounded by a sheath which is an effective barrier to the diffusion of potassium ions. The muscle-fibre membrane is also depolarized by high concentrations of potassium ions in a similar way to muscle-fibre membranes of other animals which have been previously investigated. The tracheolated membranes surrounding the muscles, and the close arrangement of the constituent fibres, delay the passage of potassium ions through the muscles. It is predicted that the mechanical properties of the muscles of a herbivorous insect will be found to be subject to fairly marked changes if the blood potassium rises or falls to an appreciable extent.
Physiological and Pharmacological Observations on Muscle Receptor Organs of the Crayfish, Cambarus Clarkii Girard
Authors: Wiersma C. A. G. , Furshpan E. , Florey E. 
Published: April 2021

ABSTRACT
The muscle organs recently described by Alexandrowicz in the tails of Homarus vulgaris and Palinurus vulgaris, have also been found to be present in the crayfish (Cambarus clarkii) and the rock lobster (Panulirus interruptus), and a study of them in the latter animals has been undertaken. The position of these units within the abdomen of the crayfish differs from their position in the lobsters. In almost all other respects, however, there is substantial correspondence in their morphological features. The organs are easily isolated and it is found that stretching them is accompanied by a discharge in one of the axons supplying each unit. There are two receptors in each half-segment of the abdomen and their responses show considerable differences. One has a very low threshold and can be sustained in continuous discharge for several hours. The threshold of the other is high and this receptor usually adapts completely to the most extreme stretch in less than 1 min. A phenomenon which is designated ‘over-stretch’ has been observed. All-but-maximal stretch causes a reversible cessation of the previous high-frequency discharge. The discharge can be restored by slight release of tension, but even if the tension producing ‘over-stretch’ is maintained for a sufficient length of time, discharge will resume spontaneously. The possibility that this spontaneous return is due to a slow rupture of the receptor tissues is not excluded. The muscular regions of the organs are not necessary for their sensory function. It has been possible to show that stimulation of the nerve trunk can induce contraction in these muscular regions and that such contraction results in discharge in the sensory axons. The unit with the low stretch-threshold responds to low concentrations of ACh and this effect is potentiated by eserine. In concentrations above 10−6 before eserinization and above 10−8 after eserinization, ACh consistently initiates rhythmic responses in relaxed units and augments the discharge from those under tension. ACh affects the sensory mechanism directly; the muscular regions of the organs are not necessary for its action. Atropine inhibits the ACh excitation, but only increases the response of the receptors to stretch. Eserine, except in high concentrations, has no consistent effect on the normal stretch discharge. The possibility that ACh has a role in the normal receptor mechanism is discussed, but the question is left open.
The Release of Phosphate From the Electric Organ of Torpedo
Authors: Fatt P. , Woodin A. M. 
Published: April 2021

ABSTRACT
A technique is described for perfusing the isolated electric organ of Torpedo. With a constant perfusion pressure the admission of acetylcholine is found to cause an appreciable reduction in the rate of flow. Orthophosphate, sulphate, glutamate and aspartate have been identified as anions which pass from the electric organ into the fluid perfusing through it. With a perfusion rate of 4-8 ml./min., repetitive stimulation of the nerve caused an increase in the rate of phosphate released from the organ. The phosphate concentration in the venous effluent rose to a maximum of about 180% of the resting level, and stimulation to exhaustion resulted in the release of an additional 10 μmol. of phosphate. Perfusion of an electric organ by acetylcholine elicited a slowly developing response amounting at the most to about 1 mA. when passed into a low resistance and lasting for about 7 min. The possible role of intra-electroplate anions in generating the discharge of the Torpedo electric organ is discussed. The additional phosphate released from the organ on stimulation accounts for only 1 % of the charge which crosses the active electroplate membrane.
Polarized Light Studies Of The Cornea
Authors: Stanworth A. , Naylor E. J. 
Published: April 2021

ABSTRACT
The importance of the cornea and the peculiar circumstances of its transparency have stimulated research for many years, but despite its apparent suitability there have not been any adequate quantitative investigations by means of polarized light. We shall show in this and the following paper that this technique, besides yielding results which throw light on the ultrastructure and fibre arrangement of the tissue (Naylor, 1952), also affords a means of assessing changes in the intra-ocular pressure of the intact eye by quantitative measurements of the photo-elastic properties of the cornea.
Polarized Light Studies of the Cornea
Authors: Stanworth A. 
Published: April 2021

ABSTRACT
A method is described of measuring the birefringence of the intact cornea using light reflected obliquely from its posterior surface. The value obtained (0-0037) is in reasonable agreement with the results obtained by using transmitted light and from corneal sections. The change in birefringence with an increase in intraocular pressure from 10 to 40 mm. Hg is about 7 % of this. The change in birefringence was also assessed by changes in the density of the photographic image of the reflected light from the surface, and this affords a possible way in which the intraocular pressure could be measured in the human subject without touching the eye.
On Certain Properties of the Flight Muscles of the Orthoptera
Authors: Ewer D. W. , Ripley S. H. 
Published: April 2021

ABSTRACT
The physiological characteristics of the wing musculature of insects have been but little investigated. Solf (1931) has given a brief account of the responses of the dorsal longitudinal muscles of Gryllotalpa vulgaris (L.) to direct electrical stimulation. A more extensive study has been made by Heidermanns (1931) of the responses to direct electrical stimulation of the wing muscles of Aeschna coerulea (Strom). The latter author found that at a stimulation frequency comparable with that of the normal wing beat of the dragonfly, the muscles were in a partial tetanus. He concluded that this was their normal condition in flight. More recently, Pringle (1949) has found that potentials recorded from the wing muscles of Calliphora occur at a lower frequency than the wing movements. He concluded that these flight muscles were highly specialized, and that impulses from the nervous system activated rather than excited the muscles. Similar observations have been made by Roeder (1950, 1951) on Vespa, Lucilia and Tabanus. In Periplaneta and the moth Agrotis, however, Roeder recorded a single muscle potential for each cycle of the wing beat. He concludes that in the latter two species the wing-beat frequency was such as to permit a conventional neuromuscular system to move the wings.
Relation of the Rate of Antennal Movement in Daphnia to the Number of Eggs Carried: In the Brood Pouch
Authors: Fox H. Munro , Mitchell Yvonne 
Published: April 2021

ABSTRACT
The number of parthenogenetic eggs and embryos carried in the brood pouch of Daphnia varies greatly. In some natural populations of the pond-dwelling species females carry many eggs,* in other populations they have few. We have found in nature a female of D. magna Straus carrying 95 eggs, and de Kerhervé (1926) had one in culture with 105 eggs, whilst, on the other hand, in some natural populations of the same species no more than one, two or three eggs are borne. Two potent causal factors influencing egg number are the quantity of food and the aeration of the water : up to a certain maximum level of feeding, the number of eggs produced is proportional to the quantity of food eaten (Ingle, Wood & Banta, 1937; Fox, Hardcastle & Dresel, 1949), and below a certain degree of aeration of the water the egg number falls off proportionately to the amount of dissolved oxygen (Fox, Gilchrist & Phear, 1951). In addition, fewer eggs are produced at a high temperature (MacArthur & Baillie, 1929; Fox & Phear, 1953). Other factors influencing the egg number are the nature of the food (Lefèvre, 1942) and the age of the mother (Anderson, Lumer & Zupancic, 1937).
Further Studies on Ionic Regulation in Marine Invertebrates
Authors: Robertson James D. 
Published: April 2021

ABSTRACT
The blood or coelomic fluid has been analysed in sixteen marine invertebrates to determine the amount of ionic regulation. Little regulation is shown by Holothuria and the bivalves Ostrea and Mytilus except in potassium. The bivalves accumulate potassium (up to 135% of the concentration in sea water), and Mytilus galloprovincialis accumulates sulphate (to 120%), an unusual feature. The nudibranch Archidoris accumulates potassium (128%), calcium (132%) and magnesium (107%), while the sipunculid Phascolosoma has lower magnesium (69%) and sulphate (91 %) but higher sodium (104%). The cephalopod Sepia regulates all its ions except magnesium, range of values (expressed as percentage of concentration in dialysed plasma) being Na 92-94%, K 193-223%, Ca 84-97%, Mg 97-100%, Cl 105-106%, SO4 17-29%. Protein averages 109 g./l. in the three specimens analysed. Fluid from the renal sacs contains high concentrations of NH4+ ions, in two specimens 146 and 59 m.equiv./kg. water, and differs from a plasma ultrafiltrate in the concentration of all other ions. The vitreous humour in the cephalopod eye is a clear protein-free fluid, isosmotic with the plasma within 1% but having ionic concentrations markedly different from those of a plasma ultrafiltrate or dialysate. In Sepia, Loligo and Eledone magnesium may be only 10-20% and sodium over 115% of the concentrations in a dialysate of the plasma. In one specimen of Sepia the aqueous fluid in front of the lens largely resembled sea water except for lower concentrations of magnesium and sulphate. Among the decapod and stomatopod Crustacea regulation of all ions exists, ranges in eight species being Na 97-111%, K 120-156%, Ca 84-137%, Mg 32-99%, Cl 96-103%, SO4 53-135%. Species of Portunus and Eupagurus show more regulation than Dromia and the spider-crabs Maia and Hyas. Regulation in the stomatopod Squilla resembles that in the portunid family. In the grapsoid crab Pachygrapsus each ion in the plasma is maintained below its equilibrium value: Na 94%, K 95%, Ca 92%, Mg 24%, Cl 87%, SO4 46%; total ions 1·163 g. ions/kg. water compared with 1·353 in sea water. In sixteen crustaceans an inverse relationship exists between the degree of activity and the magnesium content of the blood: the more active ones have low values of magnesium.
Osmotic Relations in Molluscan Contractile Tissues
Authors: Pilgrim R. L. C. 
Published: April 2021

ABSTRACT
The bivalve molluscs include marine, estuarine and fresh-water forms, and they yield good heart and cilia preparations. Although the ecological distribution and powers of osmoregulation of several species have been studied in detail, little is known about the effects of osmotic pressure on the functioning of their tissues. At the suggestion of Dr G. P. Wells, the writer undertook a comparative investigation of the effects of osmotic pressure variations on the hearts and cilia of lamelli-branchs. The three species used were chosen because they are readily obtained and kept in London, where the work was done, and they represent a wide ecological range. The experiments on hearts are described in the following pages. Those on cilia will form the subject of a second paper.
A Polarized Light Analysis of the Human Red Cell Ghost
Authors: Mitchison J. M. 
Published: April 2021

ABSTRACTA new method is described for measuring the thickness of thin spherical birefringent membranes. It consists of measuring a curve of retardation against radial distance at the edge of the membrane, and comparing this curve with other curves calculated from theory for membranes of known thickness. Diffraction is taken into account. This method shows that the wet thickness of the human red cell ghost in glycerol is about A good agreement with the experimental results would be given by a model membrane consisting of a weakly birefringent layer 0·5μ thick surrounded by a strongly birefringent layer 40 A. thick. It is suggested that the thick layer is a 2 % protein gel, and that the thin layer is a bimolecular layer of lipids. The birefringence indicates that there is radial molecular and tangential micellar orientation in the protein gel. This can be explained by an arrangement of the protein chains in looped bundles. On the basis of these results a new model is put forward for the structure of the red cell membrane, and some of its implications are discussed.
The Lipids of Sea-Urchin Semen
Authors: Cardin A. , Meara M. L. 
Published: April 2021

ABSTRACT
The constitution of the lipid material present in semen has received very scant attention. No reference appears in the literature relating to the component fatty acids of semen lipids, although the presence of neutral fat, free fatty acid, free and combined sterols, phosphatides, and sphingomyelin has been reported by Woodhouse (1928) in the sex organs of domestic animals and of humans ; likewise, Sakaki (1913) reported the presence of phosphatides and sphingomyelin in the human placenta; Sano (1922) reported the presence of these phosphatides in the fresh ‘sperm freed from membranes and connective tissue ‘of the cod, porgy and salmon. More recently, Lardy & Phillips (1941), in an investigation of the sources of energy for bull spermatozoa, showed that the phospholipid content of both semen and spermatozoa decreased when incubation was carried out in the absence of extracellular substrates but in the presence of oxygen.