bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Functioning of the Giant Nerve Fibres of the Squid1
Authors: Young J. Z. 
Published: April 2021

ABSTRACT
Stimulation of single giant nerve fibres in the stellar nerves of the squid (Loligo pealii) shows them to be motor axons which produce contraction of the circular fibres of the mantle muscles. When a stellar nerve is stimulated with condenser discharges a maximal response is obtained at threshold voltage. No increase of response is obtained by further increase in the strength of stimulation except for an occasional slight increase at about ten times threshold voltage probably due to repetitive firing. It therefore appears that the stimulus produces a single impulse in the giant fibre, and that this is capable of exciting contraction in all the muscle fibres which it reaches. This confirms the conclusion reached on histological grounds that in spite of their syncytial nature each of the giant nerve fibres is a single functional unit. Since there are about ten giant fibres on each side the mantle is divided into 20 neuromotor units, each nerve fibre innervating an enormous number of muscle fibres. The existence of these units can also very readily be demonstrated by the fact that threshold electrical stimulation at any point within the territory innervated by each single giant fibre sets up a contraction of the muscle fibres of all parts of the territory with which the stimulated area is in connexion through the nerve. Stimulation of the smaller fibres in a stellar nerve after destruction of the giant fibre also causes contraction of the circular muscles of the mantle. The amount of this contraction increases progressively with increased voltage, presumably on account of the stimulation of more and more nerve fibres. The maximum tension developed in this way is always very much less than that produced by stimulation of the giant fibres. The mantle is therefore provided with a double mechanism of expiratory contraction, maximal contractions being produced by single impulses in the giant fibres and graded contractions by those in the smaller fibres of the nerve. Presumably the former contractions are those involved in rapid movement, the latter in respiration. There are also radial muscles, running through the thickness of the mantle, whose contractions effect the inspiration by making the cavity larger.
The Effect of Testis Hormone on the Preservation of Sperm Life in the Vas Deferens of the Fowl
Authors: Munro S. S. 
Published: April 2021

ABSTRACT
As a result of the suggestion by Crew (1922), verified by Fukui (1923 a, b, c) and also independently by Moore and his associates (Moore, 1924 a, b; Moore & Chase, 1923; Moore & Oslund, 1924), the scrotum is now known to act essentially as a thermoregulator, the duty of which is to maintain a physiologically optimum temperature for testis function. Moore & Quick (1924) have shown that the temperature of the scrotum in various laboratory rodents is from 1 to 7° C. below peritoneal temperatures; and Fukui, and Moore and his collaborators, as quoted above, have shown conclusively that the mammalian testes do, in fact, require to be maintained at temperatures lower than those of the body in order to carry to completion their function of germ cell differentiation. If the temperature of the scrotum is experimentally raised to that of the body, the germinal epithelium shows rapid, and eventually complete, degeneration and the resulting atrophic testes consist of connective and interstitial tissue with very little but Sertoli cells discernible within the tubules. The sensitivity of germinal tissue to heat is extended to the mature spermatozoon since Heller (1929) found that sperm in the scrotal epididymis will live for 65 days, whereas this period is reduced to 14 days when the epididymis is elevated into the abdomen. Further, the very short life of mammalian sperm in the reproductive tract of the female, usually a matter of hours (for review see Hartmann, 1932), is presumably due also to the destructive action of heat.
On Galvanotropism and Oscillotaxis in Fish
Authors: Harreveld A. Van 
Published: April 2021

ABSTRACT
A spinal fish bends with the concave side towards the anode in a D.C. field of transverse direction. This reaction, which lasts as long as the current passes, is shown to be a reflex (galvanotropic reflex). Other manifestations of this reflex have been found. In a field of dorso-ventral direction the animal is bent in the sagittal plane towards the anode. The unrest of body and tail in an ascending field in the longitudinal direction of the fish may be caused partly by the same reflex. The same reflex has also been found in some of the fin muscles. The structures (sensory end-organs) stimulated during the galvanotropic reflex are situated in the muscles (or tendons).
Galvanotropism has been demonstrated in fish in which the labyrinths and the lateral-line organs have been eliminated by the transection of their nerves.
The mechanism of galvanotropism is discussed and this phenomenon is found to be based on the galvanotropic reflex and the ability of the animal to swim.
A fish placed at 45° to the current lines in an A.C. field shows a curving of the body and tail. This is explained by the wedge shape of the fish body and tail, by which the two sides of the animal have a different angle with the current lines, and thus are differently stimulated. The mechanism of oscillotaxis is discussed in relation to this reaction.
The Respiration of Nematodes of the Alimentary Tract
Authors: Davey D. G. 
Published: April 2021

ABSTRACT
Because of their peculiar habitat, tacitly assumed to have an oxygen content small enough to be negligible, the metazoan parasites living in the alimentary canal of various animals have long been the subjects of respiratory studies. The work of the earlier investigators reached its culmination in Weinland’s animal fermentation theory, put forward to explain the anaerobic existence of Ascaris lumbricoides and A. megalocephala. The fundamentals of the theory are embodied in the well-known equation
The Effect of Carbon Monoxide on the Oxygen Consumption of Drosophila Melanogaster Pupae
Authors: Wolsky Alexander 
Published: April 2021

ABSTRACT
The aim of these investigations is a study of the effect of carbon monoxide on developmental processes in Drosophila. Such a study involves, of course, a determination of the carbon-monoxide action in a quantitative manner, and for this purpose it seemed to be most suitable to undertake a study of the oxygen uptake in different pupal stages, first under normal conditions and then in various mixtures of oxygen and carbon monoxide.
The Regulation of Osmotic Pressure and Chloride Concentration in the Haemolymph of Mosquito Larvae
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
In an earlier paper (Wigglesworth, 1933b) it was shown that the cuticle of the mosquito larva Aedes aegypti (= argenteus) is permeable to water only at the anal papillae, and that water is taken in continuously by these organs and excreted by the Malpighian tubules; observations which were confirmed by Pagast (1936). But a more important function of the anal papillae has recently been made clear by Koch (1938), who has shown that in larvae of Chironomus and Culex they absorb chloride ions. They are able to take up chloride from very dilute solutions (0·001 M) and behave in this respect like the skin of frogs and other fresh-water animals as demonstrated by Krogh (1937).
The Control of Photo-Pigmentary Responses in Eyeless Catfish
Authors: Wykes Ursula 
Published: April 2021

ABSTRACT
In common with certain other teleosts and lacertilians, eyeless Amiurus nebulosus and Fundulus heteroclitus show a pigmentary response to changes in intensity of illumination. The melanophores contract in the darkness and expand in bright light. The control of this photic response was investigated in Amiurus. The contraction in darkness was not obtained in areas denervated by section of spinal nerves nor in the posterior part of the body after section of the cord. The response is therefore under the control of nervous reflexes passing through the brain. A similar melanophore contraction can be obtained by electrical stimulation of the cord at extremely low frequencies. The response remained in pinealectomized animals. Photoreceptors may possibly be located in the skin or the wall of the diencephalon may be sensitive to light. After hypophysectomy the response continues but the degree of melanophore expansion in bright light is diminished. The expanding hormone of the pituitary is therefore important in that it augments a melanophore response which is under nervous control.
The Oxygen Affinity of Haemoglobin in Splenectomized Bullfrogs
Authors: Mccutcheon F. H. 
Published: April 2021

ABSTRACT
Evidence obtained from previous studies suggests that one of the factors which influence the affinity of amphibian haemoglobin for oxygen is the locus of erythrocyte formation (Barcroft, 1934; Hall, 1934). It has been shown for the developing bullfrog (McCutcheon, 1936), and also for different species of the class Amphibia (McCutcheon & Hall, 1937), that the oxygen dissociation curve shifts from left to right depending upon the extent to which the specimen is aquatic, semiaquatic, or terrestrial.
Studies in Reptilian Colour Changes
Authors: Kleinholz L. H. 
Published: April 2021

ABSTRACT
Anolis becomes dark brown on a light-absorbing background and bright green on a light-dispersing background, the changes being accomplished by a dispersion or concentration of pigment within melanophores. Blinded lizards lose the ability to respond to changes in backgrounds, but become brown when in light and green when kept in darkness. Hypophysectomy results in permanent pallor. The brown colour can be temporarily elicited in such lizards by injection of appropriate extracts of the pituitary gland. Denervated regions of skin undergo normal colour changes. Electrical stimulation of hypophysectomized lizards evokes a mottled pattern. Mottling is under hormonal and not under nervous regulation.
Studies in Reptilian Colour Changes
Authors: Kleinholz L. H. 
Published: April 2021

ABSTRACT
Melanophore contraction is not effected through a direct nervous agency, nor are the adrenal glands normally necessary to mediate the light state. The concentrated state of melanophore pigment is ordinarily due to the disappearance of the melanophore-dispersing hormone from the circulation. The rapid onset of pallor which follows electrical stimulation may be due to a vasoconstrictor effect. Intact skin in hypophysectomized lizards does not respond directly to light, but isolated skin darkens slightly in bright sunlight and becomes bright green again in diffuse light. Isolated skin responds to hormones, becoming generally dark in solutions of pituitary extract and showing the mottling reaction in solutions of adrenalin.
The Dynamics of Quadrupedal Walking
Authors: Manter John T. 
Published: April 2021

ABSTRACT
The cat was used as a representative quadruped for a study of the action of the locomotor apparatus in walking. In the analysis the body was considered as being made up of eleven parts behaving in such a fashion that they could be considered as rigid bodies. The weight of each part was determined, the position of its centre of gravity and also its moment of inertia. Moving pictures were taken of the cat walking over a specially constructed platform which recorded the pressure exerted by each foot during the stride. The photographs recorded the position of the various parts of the body at successive instants. These records were analysed in terms of displacement, velocity and acceleration of the centre of gravity of the body as a whole, and also of its parts.
A comparison of vertical forces acting on single limbs of the cat during the walk shows that the reactions are greater on the forelimbs. This is not only due to the location of the centre of gravity nearer the forelimbs, but also is the result of a thrust produced at the forelimb which is largely responsible for an upward acceleration of the centre of mass of the body. Horizontal forces produced at the forefeet also tend to be greater than those at the hind. When horizontal impulse over the whole step is considered, it is shown that the forelimbs produce more retarding action, while the hindlimbs contribute more forwarding impulse to the body. The arrangement of steps is such that horizontal reactions on fore- and hindlimbs are antagonistic, thus damping fluctuations in horizontal acceleration and velocity of the centre of gravity with a probable saving in energy expenditure.
The kinetic energy of the body, derived from the data of the mass and velocity of separate parts, maintains an average level but undergoes cyclical changes during the stride. A possible transfer into gravitational potential energy can account for only a part of these kinetic energy changes which are thought to involve muscle action.
An analysis of the relationship between muscle forces about the joints and forces of reaction which co-operate to produce the recorded movement of an individual segment of the limbs allows the calculation of the resultant muscle torque acting on that segment. This provided actual measurements for the total muscle torque about each of the joints of the limbs at any instant. Correlation of these torques with the action of definite muscle groups indicates roughly the manner in which these muscles function in quadrupedal walking.
The Temperature and Humidity Relations of the Cockroach
Authors: Gunn D. L. , Cosway C. A. 
Published: April 2021

ABSTRACT
In a diffusion gradient of humidity at uniform temperature, some cockroaches (Blatta orientalis, L.) show a tendency to spend more time in the drier region. Other individuals appear to be indifferent to the stimulus of air humidity. On desiccation, there is a tendency for cockroaches to become hygro-positive. In a temperature gradient, those individuals which react to humidity have a slightly but significantly higher preferred temperature in somewhat moist air than they have in dry air. It seems, then, that the observed preferred temperature represents a kind of balance between a pure temperature reaction and a humidity reaction. The change in humidity reaction resulting from desiccation is qualitatively satisfactory to explain the fall in preferred temperature which occurs at the same time.
Bite-to-bite variation of muscular activity in cats
Authors: Gans Carl , Gorniak Gerard C. , Morgan William K. 
Published: April 2021

ABSTRACT
Changes in electromyographic (EMG) activity between successive bites in the jaw-closing muscles of cats are described for the reduction of food with different textures. Plots of these data suggest, and statistics confirm, that one cannot predict the magnitude of EMG activity from one bite to the next, but that predicting the direction of change in EMG activity (i.e. increases or decreases) may be possible, given the relative magnitude of a bite. The patterns observed also show that the degree of variability between masticatory cycles differs among the jaw-closing muscles and with food texture. These patterns of muscle activity are related to the neural control of jaw movements.
Nonspiking Pathways in a Joint-control Loop of the Stick InsectCarausius Morosus
Authors: Büschges Ansgar 
Published: April 2021

ABSTRACTIn the stick insect Carausius morosus (Phasmida) intracellular recordings were made from local nonspiking interneurones involved in the reflex activation of the extensor motoneurones of the femur-tibia joint during ramp-like stimulation of the transducer of this joint, the femoral chordotonal organ (ChO). The nonspiking interneurones in the femur-tibia control loop were characterized by their inputs from the ChO, their output properties onto the extensor motoneurones and their morphology. Eight different morphological and physiological types of nonspiking interneurones are described that are involved in the femur-tibia control loop. The results show that velocity signals from the ChO are the most important movement parameter processed by the nonspiking interneurones. Altering the membrane potential of these interneurones had marked effects on the reflex activation in the extensor motoneurones as the interneurones were able to increase or decrease the response of the participating motoneurones. The processing of information by the nonspiking pathways showed another remarkable aspect: nonspiking interneurones were found to process sensory information from the ChO onto extensor motoneurones in a way that seems not always to support the generation of the visible resistance reflexes in the extensor tibiae motoneurones in response to imposed flexion and extension movements of the joint. The present investigation demonstrated interneuronal pathways in the joint-control loop that show ‘assisting’ characteristics.
Blood Respiratory Properties and the Effect of Swimming on Blood Gas Transport in the Leopard Shark Triakis Semifasciata
Authors: Lai N. Chin , Graham Jeffrey B. , Burnett Louis 
Published: April 2021

ABSTRACT
Changes in vascular pressures, blood respiratory properties and blood gas transport induced by swimming were investigated in the leopard shark Triakis semifasciata (Girard). In resting sharks, the mean ventral and dorsal aortic pressures (systolic/diastolic) were 6.8/5.6 kPa and 4.5/3.9 kPa, respectively, and only the former were increased significantly during swimming. Swimming also caused a significant decline in venous , (1.6 to 0.9kPa), O2 content (0.9 to 0.4 mmol l−1) and percentage O2 saturation (, 39 to 18%) but the arterial variables were not affected. A significant decline in venous pH and an increase in venous also occurred during swimming but lactate concentration did not increase during or after swimming. An in vivo dissociation curve compiled from blood and data for sharks in the resting, swimming and post-swimming recovery phases shows a mean P50 of 2.04 kPa, as determined by Hill transformation. The pH-bicarbonate plot for this fish shows a weak blood buffer capacity of 9.3 mmol I−1 pH unit−1 and during swimming the average blood pH and bicarbonate concentration follow the buffer line which was not compensated in recovery. Neither oxygenated nor deoxygenated blood pH values were affected by CO2 equilibration, suggesting the absence of a Haldane effect. Thus, at the expense of respiratory acidosis, Triakis can aerobically sustain long (up to 60 min) and moderately intense (0.45 Ls−1, where L is body length) periods of swimming by increasing cardiac output and tapping its venous reserve.
Ionic Basis of Membrane Potential and of Acetylcholine-Induced Currents in the Cell Body of the Cockroach Fast Coxal Depressor Motor Neurone
Authors: David Jonathan A. , Sattelle David B. 
Published: April 2021

ABSTRACTThe ionic basis of the resting potential and of the response to acetylcholine (ACh) has been investigated in the cell body membrane of the fast coxal depressor motor neurone in the metathoracic ganglion of the cockroach Periplaneta americana. By means of ion-sensitive microelectrodes, intracellular concentrations of three ion species were estimated (mmol l−1): [K+]i; 144±3; [Na+]j, 9±1; [Cl ],, 7±1. The resting potential of continuously superfused cells was –75.6±1.9mV at 22°C. A change in resting potential of 42.0±2.5mV accompanied a decade change in [K+]o. Experiments with (10−4mol l−1) ouabain, Na+ injection, low temperature (10°C) and non-superfused cells indicated the presence of an electrogenic sodium pump.Under current-clamp, the cell body membrane was depolarized by sequentially applied, ionophoretic pulses (500ms duration) of ACh. Under voltage-clamp, such doses of ACh resulted in an inward current which was abolished in low-Na+ saline. Ion-sensitive electrodes revealed an increase in [Na+]i but no change in [Cl”]i in response to externally applied ACh. The ACh-induced current-voltage relationship was shifted in a negative direction by low-K+ saline. The ACh-induced inward current was usually followed by a delayed outward current which reversed at EK. Low-K+ saline had the same effect on this outward component as depolarizing the membrane. This suggests that the outward current component is carried by K+.The ACh-induced inward current and the delayed outward current were potentiated either when [Ca2+]i was lowered by injecting the calcium chelator BAPTA or by exposure of the cell to low-Ca2+ saline. High-Ca2+ saline reduced the inward component of the response and produced a negative shift in the ACh-induced current-voltage relationship. The amplitude of the delayed outward current was enhanced initially and then depressed when the cell was exposed to high-Ca2+ saline.The ACh-induced current in this neuronal cell body appears to be carried by Na+, K+ and, to a lesser extent, Ca2+. It is suggested that the delayed outward component is due to a combination of (i) Ca2+ entering the cell and activating a K+ conductance and (ii) Na+ entering the cell and stimulating the Na+/K+ pump. Ca2+ appears to regulate the permeability of the ACh-receptor-operated ion channel. Reducing the level of intracellular or extracellular Ca2+ increases the ACh-induced current. Possible mechanisms are discussed.
Salinity-induced Changes in Branchial Na+/K+-ATPase Activity and Transepithelial Potential Difference in the Brine ShrimpArtemia Sauna
Authors: Holliday Charles W. , Roye David B. , Roer Robert D. 
Published: April 2021

ABSTRACTSilver staining of the adult brine shrimp, Artemia salina, revealed that only the metepipodites of the phyllopodia were significantly permeable to chloride and/or silver ions. The metepipodites stained in a reticulated pattern, possibly indicating areas in the cuticle over cells specialized for chloride secretion. Crude homogenates of metepipodites had very high Na+/K+-ATPase enzyme specific activity (ESA) which increased in proportion to the salinity of the external medium and, thus, in proportion to the need for outward salt transport in these strongly hypo-osmoregulating animals. Metepipodite ESA as a percentage of whole-body ESA increased from 7·6% in 50% sea water (SW) to 25·0% in 400% SW. Gut and maxillary gland also had high Na+/K+-ATPase ESAs, implicating these organs in osmoregulatory processes as well. The time courses of increases in phyllopodial and gut ESAs in brine shrimps transferred from 100% SW to 400% SW are consistent with the induction of new Na+/K+-ATPase; 4–7 days was required for significant increases to occur. Haemolymph ion analyses and transepithelial potential differences, measured in brine shrimp acclimated in all the SW media, indicate that chloride is actively transported out of the brine shrimp while sodium is very close to electrochemical equilibrium across the body wall. Thus, the metepipodites of the brine shrimp appear to possess cells with many functional similarities to the teleost branchial chloride cells.
The effect of appendage and scale loss on instar duration in adult firebrats,Thermobia domestica(Thysanura)
Authors: Buck C. , Edwards J. S. 
Published: April 2021

ABSTRACTThe loss of appendages immediately following a moult shortens the subsequent intermoult interval in adult Thermobia domestica. The loss of increasing numbers of appendages accelerates the ensuing moult incrementally. Leg amputation at sites distal to the trochanter-femoral autotomy plane has comparable effects in accelerating the moult. Functional legs regenerated at the first moult following amputation are at least 80% of normal length, while abdominal cerci are regenerated at a slower pace, attaining about 20% of normal length at the first post-operative moult. Scale loss also causes an acceleration of the following moult. It is proposed that changes in diffuse sensory input, rather than specific proprioceptive feedback, mediate the acceleration of the moult cycle.