bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurohormonal Modulation of theLimulusHeart: Amine Actions on Cardiac Ganglion Neurones
Authors: Augustine George J. , Fetterer Raymond H. 
Published: April 2021

ABSTRACTOctopamine (OCT), dopamine (DA), epinephrine (EPI) and norepine-phrine (NE) are endogenous excitors of the Limulus heart. The cellular sites of action of these amines were investigated by recording responses of neurones in the cardiac ganglion. There was an increase in spike frequency in pacemaker neurones, accompanied by a depolarization and an increase in the rate of repolarization of the ‘pacemaker potential’. DA also produced a transient decrease in pacemaker spike frequency which preceded its excitatory effect. All four amines produced slow, dose-dependent increases in the frequency of bursting activity in cardiac ganglion follower neurones. These increases were blocked by the antagonist phentolamine. DA and NE also produced transient decreases in burst rate which were blocked by the antagonist metergoline. Local application of DA on to pacemaker cells increased follower cell burst frequency, while similar applications on to follower cells did not affect burst frequency. This indicates that DA acts directly upon pacemaker neurones to increase cardiac ganglion burst activity. In addition to their pacemaker-mediated effects, the amines also had direct effects upon follower cells. These effects were examined after eliminating follower cell bursting activity with cobalt ions. OCT and, to a smaller extent, EPI, depolarized follower cells. DA and, occasionally, NE hyperpolarized follower cells. The hyperpolarizing DA response was due to a conductance increase and was blocked by metergoline and ergonovine.
Sperm Receptivity in Sea Urchin Oocytes and Eggs
Authors: Dale Brian 
Published: April 2021

ABSTRACT
An electrophysiological method for studying the receptivity to spermatozoa of sea urchin eggs and oocytes is described. Pairs of adjacent oocytes and eggs, with intact jelly layers, were impaled and simultaneously exposed to a known concentration of spermatozoa. Two parameters were studied. The time from insemination to the first successful collision (as indicated by a step depolarization across the egg plasma membrane) and the total number of successful collisions. Sperm densities of 107ml-1 were used, which ensured almost immediate interaction between several thousand spermatozoa and each female gamete. In all cases, under control conditions, the oocyte was more receptive to spermatozoa than was the egg, giving rise to the first electrical event at about 5 s post-insemination, compared to about 13 s for the egg. In addition, whereas 10-15 spermatozoa usually entered the oocyte, only one entered the egg. The low receptivity of eggs appears to be independent of resting potential. Cytoplasmically immature eggs or mature eggs briefly exposed to nicotine, strychnine, choline or Tris tend to be polyspermic and have comparable receptivity to oocytes. The data suggest that there are a limited number of viable interaction sites on the oocyte surface and that during cytoplasmic maturation these sites are rendered less receptive. In the mature egg there may be one preferential sperm entry site. This hypothesis is consistent with the experimental data and would explain why sea urchin eggs are usually monospermic at high sperm densities.
Characterization of the Cold-Induced Contracture of the Anterior Byssal Retractor Muscle of Mytilus Edulis
Authors: Linehan Catherine M. 
Published: April 2021

ABSTRACT
When the anterior byssal retractor muscle (ABRM) of Mytilus edulis was subjected to a sudden reduction in temperature during a contractionrelaxation cycle, a tension increment, the cold-induced contracture (CIC), was observed. The CIC could be obtained in a muscle stimulated by the application of acetylcholine (ACh), caffeine or high-K+ solutions, but could not be elicited from a muscle at rest or in ‘catch’. When the muscle was released from ‘catch’ by the application of 5-hydroxytryptamine (5-HT), a CIC could once again be produced. The CIC tension elicited after the application of ACh was shown to follow a log-dose relationship with respect to ACh concentration but no CIC was observed at an ACh concentration at which the initial tension was 10% or less of maximum. The CIC tension decreased with time after the application of ACh and appeared to be dependent on both the initial and final temperatures and on the size of the temperature drop. The significance of these results and possible explanations are considered.
Cost of Locomotion: Unsteady Medusan Swimming
Authors: Daniel Thomas L. 
Published: April 2021

ABSTRACT
The influence of unsteady (time varying) motion on the energetics of swimming was investigated with measurements and theoretical estimates of the specific cost of locomotion for two species of hydrozoan medusae: Gonionemus vertens L. Agassiz and Stomotoca atra L. Agassiz. These species, both about 1 g, provide a broad range of swimming speeds for which locomotor energetics can be explored. The cost of locomotion (a dimensionless ratio defined as the rate of energy consumption divided by the product of an animal’s weight and speed) was estimated from the oxygen consumption rate of medusae tethered to a force platform. Swimming beat frequency, as monitored by the force platform, was correlated with velocity obtained from ciné-films of freely swimming medusae.
The specific cost of locomotion was 6-3 (dimensionless), nearly one order of magnitude greater than the extrapolated cost of locomotion for a vertebrate swimmer of equivalent body mass. The great magnitude of this cost is attributed to two aspects of the periodic pulsatile pattern of locomotion by these cnidarians: (1) the energy expenditure for periodic accelerations of the animal’s mass and some mass of fluid about it and (2) the energy dissipated in bell deformations and recovery strokes. Nearly 25% of the augmented cost is attributed to the energy required to overcome an unsteady flow force, that is the force required to accelerate fluid about the animal. Such a high cost of locomotion is apparently a general consequence of swimming with a discontinuous production of thrust.
The mechanics of discontinuous swimming are explored by measuring the hydrodynamic coefficients associated with unsteady flows (added-mass coefficients) for models of medusae. The results suggest that the effects of vortex formation and shedding may significantly increase the magnitude of the forces produced by or resisting unsteady animal locomotion.
On the Reactions of Isolated Parts ofParamecium Caudatum
Authors: Horton Frances M. 
Published: April 2021

ABSTRACTThe mode of swimming and reactions to acid of parts of Paramecium have been compared with the behaviour of the intact animal. Hind ends are more sensitive to acid than fore ends, which in this respect do not differ from whole individuals. Pieces lacking oral cilia swim spirally like intact animals.
On the Sensitivity of the Chemoreceptors on the Antenna and Fore-Tarsus of the Honey-Bee, Apis Mellifica L
Authors: Marshall Joseph 
Published: April 2021

ABSTRACT
The experiments to be described were undertaken as a preliminary study of the reactions of the contact chemoreceptors on the antenna and fore-tarsus of the honey-bee, Apis mellifica L., to various concentrations of sucrose solutions. Experiments were also carried out to estimate the effect of antennal amputation on chemotropic response.
The Energy Sources in Ontogenesis
Authors: Baldwin Ernest 
Published: April 2021

ABSTRACTBy studying the respiratory quotients of developing embryos, valuable indications can be obtained as to the nature of the substances undergoing metabolic oxidation within them. Many different embryos have been made the subject of such studies, but probably only the most recent data can be wholly accepted. The values given by the earlier workers were for the most part calculated by dividing the amount of CO2 given off from a sample of the material by the amount of oxygen consumed under the same conditions. But such a method of calculation is liable to be entirely misleading, since the amount of CO2 given off from the material may be very different from the amount actually produced by metabolic oxidation. Thus, as Richardson (1929) writes: “Even when the apparatus is technically correct, errors of interpretation may arise. The quotient as measured may not reflect the concurrent oxidation. In this event, it is convenient to designate the observed quotient as the measured quotient, and the supposed quotient due to oxidation as the metabolic quotient.” It is clear that if CO2 be retained in the material under examination, e.g. on account of pH changes or the deposition of calcareous matter in the developing embryo, the measured quotient will be lower than the metabolic quotient, unless the amount of bound CO2 can be determined before and after the period during which the oxygen uptake is measured. These considerations would apply particularly to the snail eggs which formed the material for the present study ; here, as we shall see, large amounts of CO2 are required for shell formation, and consequently any quotients obtained by the earlier methods would have been grossly inaccurate and quite useless as the basis of any hypothesis as to the energy sources of the developmental processes. It is only of recent years, with the development of manometric technique, that it has been possible to make proper allowances for any retention of CO2, a fact which must be borne in mind in considering the earlier data.
The Nerve Net of the Actinozoa
Authors: Pantin C. F. A. 
Published: April 2021

ABSTRACTCertain features have been supposed to characterise the nerve net. Response is said to vary with the strength of stimulus: and while conduction may occasionally take place in an all or nothing manner, yet in general conduction is supposed to take place with a decrement. To investigate these points, the responses of Calliactis parasitica to mechanical and electrical stimuli have been investigated. Electrical excitation of the column of the anemone shows that a response results from a succession of stimuli and not from a single stimulus. The character of the response is independent of the strength of the individual stimuli. It depends solely upon the number of stimuli and upon the interval of time between them. All responses are highly developed facilitation phenomena. Each electrical stimulus induces a single excitation impulse in the nerve net. But a mechanical stimulus is followed by the discharge of a battery of impulses from the sense organs. These increase in number and frequency with the intensity of the mechanical stimulus. A response may therefore vary with the strength of a mechanical stimulus, but only in relation to the number and frequency of impulses discharged by the sense-organs. Stimulation of the intact column of the anemone shows complete conduction over its whole nerve net. Mechanical stimulation of the disc appears to show conduction with a decrement. Such a stimulus excites a battery of impulses. Each impulse is conducted without decrement, but it facilitates the entrance of succeeding impulses into adjoining sections of the disc nerve net. There is no decrement of excitation strength under any conditions in the nerve net. But there may be a numerical decrement as a battery of impulses spreads from a stimulus. The nerve net is physiologically similar to ordinary nerve. A method is described for determining the strength duration relationship for the threshold of electrical excitation of the nerve net. The relation is of the usual form with a chronaxie of about 2·4σ. The nerve net has well-defined relative and absolute refractory periods: the latter is about 40·65σ. The relation of facilitation to refractory period is considered. The whole nerve net of the column of the anemone acts as a conducting layer in its most simple form, directly transmitting excitation from the stimulus to the muscle. Facilitation takes place between the nerve net and its appropriate muscles. Conduction in the disc nerve net involves facilitation between parts of the nerve net in addition. The true characteristics of the nerve net are diffuse conduction and the extreme development of facilitation. Diffuse conduction may be total, as in the column, or restricted, as in the disc of Calliactis. Facilitation may be between the nerve net and the muscles, or between parts of the nerve net.
The Nerve Net of the Actinozoa
Authors: Pantin C. F. A. 
Published: April 2021

ABSTRACTStimulation of the column of the anemone Calliatis parasitica elicits a graded series of responses. Each response is primarily due to the action of a single set of muscles. The means by which this effect is produced is physiologically simple. Part of the nerve net beneath the intact column behaves as a single conducting unit and the various muscles communicate with it. The muscles, however, are only activated through the facilitation of a series of impulses. Each muscle has its own appropriate frequency range, to which a facilitated response can be obtained. The range of frequencies is extraordinarily low, from 1 impulse in 1 sec. to 1 impulse in 10 sec. “Interneural” facilitation can be demonstrated between adjacent conducting units of the nerve net of the disc. From various points on the disc several stimuli may be required to establish a conducting path to the sphincter muscle. The apparent continuity of conduction throughout the column in the intact animal is due to specialised tracts running vertically up the mesenteries. These are joined by a conducting ring in the neighbourhood of the sphincter. In addition to this “through-conduction” system, there is a general nerve net within the column wall in which interneural facilitation is evident. The velocity of conduction in the general nerve net of the column has the slow rate of 10–20 cm. per sec. But for the sphincter-mesenteric system the rate is over 1 metre per sec. The relative development of both interneural facilitation and of conduction velocity within the nerve net give consistent pictures of its physiological organisation. These agree with its morphological organisation. Comparison with other species shows that the through-conduction system is a specialisation, developed in varying degrees in different species. It is most highly developed where protective reactions are most perfect, as in Calliactis. The importance of the “impulse group” propagated from a stimulated sense organ as the natural unit in behaviour of Calliactis is discussed.
The Temperature and Humidity Relations of the Cockroach
Authors: Gunn D. L. 
Published: April 2021

ABSTRACTPrevious studies in this series (Gunn, 1933, 1934) have dealt with certain aspects of the physiology of the common black beetle, Blatta orientalis. The present paper is a comparison of that and two other exotic native species of cockroaches. The smallest of the three, Blatella germanica, is found in hotel kitchens, hospitals and public houses, and most rarely in private houses. Development from hatching to the last moult occupies 3 months at 23 ° C. (Zabinski, 1929). Blatta orientalis is very common in similar places and also in older houses of the poorer class. Its development occupies 1 year at 23° C. (Zabinski, 1929). Periplaneta americana, the largest species, seems to be found only in the tropical houses in Zoological and Botanical Gardens. The duration of its life cycle appears to be unknown. No reasons have hitherto been given for the existing distribution of these three species. In this paper some contributory reasons are put forward.In the experiments here described, adult males only were used. P. americana was obtained from a dealer and the other species were caught locally. All animals were kept a few days before use, and were fed on carrot and water in an oven at 25° C.
The Response of the Lamprey to Injection of Anterior Lobe Pituitary Extract
Authors: Young J. Z. , Bellerby C. W. 
Published: April 2021

ABSTRACT
There have been many investigations on the effect of administration of anterior lobe pituitary preparations on the metamorphosis and sexual development of Amphibia, but so far as can be ascertained no similar work has been done on lampreys. These animals live for several years buried in the mud as ammocoete larvae and eventually metamorphose abruptly, changing their shape and colour and acquiring eyes and a sucker. Various workers have attempted without success to produce this change by injection of iodine or thyroid extracts (Remy, 1922; Horton, 1934).
The Effect of Temperature on the Development of the Eggs and Larvae of the Cut-Throat Trout (Salmo Clarkii Clarkii Richardson)
Authors: Merriman Daniel 
Published: April 2021

ABSTRACT
The eggs of the cut-throat trout (Salmo clarkii clarkii Richardson) were raised from fertilisation through hatching at constant temperatures of 11·3, 8·25 and 6·35° C. These temperatures are well within the limits of normal development of cut-throat trout. The temperature is not the limiting factor in determining the length of the hatching period, because there are a number of other factors that may cause eggs to hatch either prematurely early or abnormally late, and thus the use of the hatching period as a comparable stage of development for eggs raised at different temperatures may result in error. The average size of cut-throat trout embryos at the moment of hatching was smaller at the higher temperatures and larger at the lower temperatures. The maximum increment of growth in the cut-throat trout occurred about the 41st day at 8·25° C. and about the 28th day at 11·3° C. The percentage of dry weight of the cut-throat trout embryos showed a steady decrease from about 25 to 14 per cent., while that of the yolks showed an increase from about 46 to 55 per cent. Cut-throat trout embryos absorbed water from the yolk and also, at a faster rate, from the environment, both somewhat before and after hatching, so that the percentage of wet weight of the larvae was steadily increasing up to the time the experiment was completed.
Modification of Mammalian Sexual Cycles
Authors: Bissonnette Thomas Hume 
Published: April 2021

ABSTRACT
Cases are given in which female ferrets, already coming into, or in, oestrus as the result of artificially increased lighting in winter and spring, underwent regression or were retarded in their activation by reduction of either intensity or duration of daily illumination. In some cases activation was resumed when light time or intensity was increased again. These results are taken to indicate that, in female ferrets, any inherent rhythm or cycle of sexual activity is modified either naturally or artificially by changes of the cycles of duration and intensity of the light to which they are exposed daily, and so made to correspond in phases with the seasons, or changed therefrom. The rising daily illumination in spring and the falling one in late summer and autumn probably accelerate and retard the sexual activity of the female ferret, or accelerate the onset of anoestrus in late summer and autumn. The data on modification of sexual cycles or activity in ferrets, so far obtained, are consistent with these conclusions.
The Origin and Fate of Urea in the Developing Hen’s Egg
Authors: Needham Joseph , Brachet Jean , Brown Robert K. 
Published: April 2021

ABSTRACTThe urea formed by the chick embryo during its development is not derived from the ammonia of general protein catabolism, either directly or by way of the ornithine cycle. Nor is it derived from uric acid by a complex uricase similar to that of fishes and Amphibia (Stransky’s complex: uricase, allantoinase and allantoicase). The uricase discovered in the chick embryo by Przylecki probably breaks down uric acid only as far as allantoin. The urea of the chick embryo is entirely derived from an active arginine-arginase system present at all stages examined from the second day of incubation onward. The arginase of the embryo, quantitatively estimated, falls off very regularly as development proceeds, reaching a minimum about the 12th day. This negative heterogony is experimentally shown not to be due to the parallel diminution of activators such as glutathione and ascorbic acid, but must be regarded as a real diminution in the relative amount of the enzyme. It forms an important support for the view of Edlbacher, hitherto mainly based on observations of tumour tissues, that arginase is an enzyme associated with high growth rate and probably nuclein synthesis, as well as with the production of urea as a vehicle of waste nitrogen. Arginase is also contained in the yolk-sac, but in much smaller quantity than in the embryo. Here also the low activity is not due to the absence of activators. Experiments made to test the possibility that the urea, once formed, might, as would be the case on Wiener’s theory, participate in the formation of uric acid, took the form of injection of possible precursors into the egg on the 12th day of development and estimation of the uric acid in the egg on the 15th. In this way it is shown that urea cannot be converted into uric acid by the chick embryo. This conclusion is in agreement with much recent work on the adult bird. A preliminary test was also made of the possibility that biuret and sarcosine could be condensed to uric acid by the chick embryo. The results were negative.
Changes in the Thyroid Gland of Certain Mammals and Birds Following Hypophysectomy
Authors: Rowlands I. W. 
Published: April 2021

ABSTRACT
The weight of the thyroid of the normal anoestrous ferret of both sexes is approximately half that of the oestrous ferret, but there is little histological difference. Hypophysectomy during oestrus or anoestrus decreases the weight of the thyroid of the ferret to a level slightly lower than that for the normal anoestrous ferret. In the hibernating hedgehog the thyroid becomes hypotrophie (Adler, 1920), and a similar condition is found in the hypophysectomised animal. No change in weight of the thyroid of the guinea-pig is noticed following hypophysectomy, but atrophy of the vesicular epithelium and distention of the vesicles with non-vacuolated colloid is regularly observed. Hypophysectomy in birds leads to similar atrophic changes in the thyroid.
Diurnal Changes in Structure and Function of the Compound Eye of Ligia Exotica (Crustacea, Isopoda)
Authors: Hariyama Takahiko , Meyer-Rochow V. Benno , Eguchi Eisuke 
Published: April 2021

ABSTRACT
The ultrastructure of the retinula cells of Ligia exotica changes diurnally and in response to light/dark adaptation. At the low phase of electroretinogram (ERG) amplitude (at noon), the arrangement of microvilli is ordered and the rhabdom is of the open type. An irregular arrangement of microvilli appears at the high phase of ERG amplitude (at midnight), when the rhabdom is of the closed type. The pigment granules disperse at midnight and assemble at noon. A centrally positioned, spike-producing eccentric cell is present in each ommatidium.
Spectral response curves based on ERG measurements have two maxima, one to light of 383 nm wavelength, the other at around 520 nm. These two peaks represent the two classes of receptor cells identified by intracellular recordings. The ERG responses to light of 383 nm and 520 nm wavelengths display a diurnal rhythmicity, being high at night and low during the day. However, the responses to green light are more strongly affected than those to ultraviolet light. Consequently, the eye displays a relatively higher ultraviolet-sensitivity during the day, whereas at night sensitivity to green light is increased.
This behaviour, which persists in continuous darkness, suggests that an endogenous mechanism is involved in bringing about the observed diurnal morphological and physiological changes in the compound eye of Ligia exotica.