bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aspects of the Organization of Central Nervous Pathways in Aplysia Depilans
Authors: Hughes G. M. , Tauc L. 
Published: April 2021

ABSTRACT
There has been little recent work on the relationship between the behaviour of gastropod molluscs and the activity of their nervous systems. Older workers (e.g. ten Cate, 1928), studied the effects of electrical stimulation of different nerves on the movements of parts of the animal. More recently observations on the spontaneous activity and electrical properties of individual cells in isolated ganglion preparations have been extensively carried out (Arvanitaki, 1942; Tauc, 1955, 1957a, b, 1958, 1960a; Hagiwara & Saito, 1959), but little attention has been paid to the importance of these phenomena in the life of the animal. Furthermore, deductions concerning the behaviour of gastropods based on observations of the activity in isolated ganglia are necessarily tentative (Hughes & Kerkut, 1956). The most recent study of neuronal pathways is that of Turner & Nevius (1951) on Ariolimax columbianus. They used external electrodes in stimulation and recording experiments and made tentative proposals concerning the layout of some of the typical neuronal connexions. As they point out, little is known of the connexions between neurones, and anatomical methods are unable to provide sufficient information about the nature of neuronal connexions over long distances. Nisbet (1961) has recently recorded impulses in the pallial nerves of Archachatina in response to tactile stimulation and has studied conduction in the nerves and across ganglia. Techniques similar to those of Turner & Nevius have been used in the present work but in addition intracellular micro-electrodes have been employed for recording the activity of individual cells in whole animal preparations. This technique is extremely valuable as the pattern of activity of single units, now well known from such cells in isolated preparations (Tauc, 1960a), gives additional information about the paths of single neurones over quite large distances.
The Imaginal Ecdysis of Blowflies. The Control of Cuticuar Hardening and Darkening
Authors: Cottrell C. B. 
Published: April 2021

ABSTRACT
Blood transfusion experiments show that normal hardening and darkening at the imaginal ecdysis of Calliphora eryihrocephala(Meigen) is brought about by the release into the blood of an active factor. Introduction of this factor into a newly emerged fly some 35 min. prior to the time at which it would normally be released is sufficient to prlivent expansion. The factor is normally released some 45 min. before the appearance of the first signs of darkening and between 3 and 15 min. after the fly has reached conditions suitable for expansion, that is at about the time of initiation of air-pumping. Decapitation at emergence will prlivent the initiation of normal hardening and darkening but not of secondary darkening. Evidently the head is concerned in the release or the control of the release of the blood-borne darkening factor. The critical period for the prlivention of normal hardening and darkening by decapitation lies between 3 and 15 min. after the fly has reached conditions suitable for expansion. Isolated abdomina behave in a manner similar to decapitated flies but their reactions are complicated by secondary darkening associated with damage. Flies deprived of their abdomina will expand at least partially but the rate of their hardening and darkening is reduced. Damage reactions resembling secondary darkening in digging flies are more extensive after damage to internal organs such as the gut than to superficial organs such as the body wall. Allowing for the effects of secondary darkening it is possible to demonstrate the occurrence of the blood-borne darkening factor by means of ligatures placed at emergence between the thorax and the abdomen. Under these conditions only the head and thorax exhibit normal darkening.
Experiments On Choice of Substrata by Spirorbis Larvae (Serpulidae)
Authors: De Silva P. H. D. H. 
Published: April 2021

ABSTRACT
Spirorbis borealis occurs typically on Fucus serratus, S. corallinae on Corallina officinalis and S. tridentatus on rocks and stones. Laboratory experiments showed that the larvae of each species select the substratum on which the species typically occurs, the substrata of the other two species and a variety of other substrata being either less favourable or very unfavourable. Larvae of S. borealis tend to be geopositive and photopositive when settling. Those of S. tridentatus are geopositive but overridingly photonegative, which explains the natural occurrence of this species in dimly lit places.
The Reaction of Blinded Goldfish to Rotation in A Centrifuge*
Authors: Howland H. C. , Howland B. 
Published: April 2021

ABSTRACT
Blinded goldfish behave in a centrifuge as if they were orienting to absolute rotation by means of a Foucault pendulum. That is, they swim so as to compensate the rate of imposed rotation about the apparent vertical. Blinded goldfish swim in the centrifuge in a plane essentially orthogonal to the apparent vertical at low accelerations and low rates of rotation. With higher rates of rotation the axis about which the fish swims leans away from the apparent vertical and towards the axis of rotation of the centrifuge. Analysis of the physics of the centrifuge shows that if the fish rotates about any axis relative to the cab of the moving centrifuge with a rate of rotation within the physiological range of its semicircular canals it will receive signals from its otocysts and its semicircular canals which would reflect contradictory information in a nonrotating environment. This fact, together with the fish’s response to absolute rotation, affords a method for quantitatively assessing the relative roles of the otocysts and the semicircular canals in orienting the free-swimming fish.
Patterned Activity of Co-Ordinated Motor Units, Studied in Flying Locusts
Authors: Wilson Donald M. , Weis-Fogh Torkel 
Published: April 2021

ABSTRACT
A brief survey of the locust flight system is presented as background for this and future studies. Included are descriptions of the wing movements, the aerodynamic parameters and the pertinent muscle anatomy and physiology. A procedure has been designed which makes it possible to study a complex locomotory pattern in terms of the activities of single nervous and muscular units, in this case during normal flight of locusts. We have found a detailed repetitive pattern which is precisely correlated with the wing movements. Fig. 24 shows the pattern during normal flight. Variations in the details of the pattern are also correlated with significant variation in the movements. During average flight most of the flight motor units fire a single time per wing stroke. In low-powered flight numerous units are inactive. With increase in power additional units are recruited and active ones may fire twice or more during a specific phase of a single wingstroke. Increase in wingstroke frequency is correlated with increase in number of active units and with earlier onset of activity so that the wing movements are braked at top and bottom by muscular activity as well as by other restoring forces. Lift is controlled by changes in wing twisting which are mainly due to changes in activity of a single two-unit muscle for each wing, the subalar muscle.
The Mechanism of Cell-Division
Authors: Gray J. 
Published: April 2021

ABSTRACTThe fact that dividing cells are usually only found in actively growing tissues does not necessarily prove that growth and cell-division are two closely correlated phenomena. Growth may be defined as an increase in the amount of organised material which is present in the cell and which is essentially part of the living machine. Cell-division, on the other hand, only implies the cleavage of the cell into two or more parts. The purpose of this work is to enquire into the relationship between the two phenomena when they are taking place together. The material used was the segmenting eggs of Echinus miliaris.
Some Effects Produced By the Hooding of Birds
Authors: Patrick Dorothy M. 
Published: April 2021

ABSTRACT
A Black velvet hood was placed over the head of a pigeon and tied round the neck with a piece of cotton, sufficiently tight to prevent the bird removing it with its claws, which it at once attempted to do. Presently some movements of progression were made along the floor, which seemed to suggest that disturbances of equilibration had supervened ; then the bird rapidly became quiescent and assumed a peculiar and unusual position, in which the head was bent over until the crown rested upon its back, with the tip of the beak pointing towards the tail.
Taste By Touch: Some Experiments With Octopus
Authors: Wells M. J. 
Published: April 2021

ABSTRACT
A method of teaching Octopus chemotactile discriminations is described. The animals can be shown to be capable of distinguishing by touch between porous objects soaked in plain sea water and sea water with hydrochloric acid, sucrose or quinine sulphate added. They can detect these substances in concentrations at least 100 times as dilute as the human tongue is capable of detecting them in distilled water. They can be trained to distinguish between equimolar (0·2 mm) solutions of hydrochloric acid, sucrose and quinine. They can also be trained to distinguish between sea water and fresh water or half-strength sea water or sea water with twice the usual quantity of salt. The function of the ‘olfactory organ’ is discussed. Chemotactile learning is discussed in relation to the means by which Octopus finds its way about the territory around its ‘home’.
The Filter-Feeding of Artemia
Authors: Reeve M. R. 
Published: April 2021

ABSTRACT
The ability of filter feeders to discriminate between particles of different kinds was given an experimental basis in the work of Harvey (1937), who found that Calanus feeding in a mixed suspension of Lauderia and Chaetocerus would take little of the latter. Marshall & Orr (1955) could not confirm these observations and in experiments with mixed suspensions of various plant cells found no clear evidence of any selection mechanism, as also did Ryther (1954) using Daphnia.
The Change of Discharge Frequency by A.C. Stimulus in A Weak Electric Fish
Authors: Watanabe Akira , Takeda Kimihisa 
Published: April 2021

ABSTRACT
A South American gymnotid Eigenmannia, changes the discharge frequency of its electric organ when a weak electric signal is applied to it with a frequency very close to that of its own discharge. Otherwise, the discharge frequency is extremely constant at a fixed temperature. When the frequency of the applied signal is higher or lower than that of the fish discharge, the response is a decrease or increase of the discharge frequency, respectively. When the two frequencies are exactly the same, the response fails to occur. The threshold of this response is very low. In one fish it was about 3 μV./cm.
A Study on the Mechanism of Cleavage in the Amphibian Egg*
Authors: Dan K. , Kojima M. Kuno 
Published: April 2021

ABSTRACT
In comparison with the large number of investigations performed on the cleavage of sea-urchin eggs, those on the cleavage of amphibian eggs are surprisingly scanty. Recent works are almost limited to two papers from Edinburgh by Waddington (1952) and by Selman & Waddington (1955). The present report is an amplification of the works of the British investigators.
Phasic Stimulation of A Thoracic Stretch Receptor in Locusts
Authors: Gettrup Erik 
Published: April 2021

ABSTRACT
Phasic sinusoidal and constant-velocity deformation was applied to a stretch receptor from the thorax of the desert locust, Schistocerca gregaria Forskil. The response was analysed with respect to the main parameters of the stimulus. The stretch receptors respond to the flight movements with 1 – 3 potentials per wing-stroke cycle. Special interest was therefore given to the first potentials of the response. At constant frequency of stimulation the phase angle of the first potential of the response was found to be independent of changes in length and length-time parameters. The period between the two first potentials was found to be related to velocity in a rather complex way. At constant frequency, the number of impulses is a linear function of maximum displacement and/or velocity. The functional significance of the relations is discussed in relation to coordination of flight and a hypothesis is proposed which explains the constancy of the wing-stroke period as the result of a stabilizing influence of the first potential of the response.
Micropuncture Studies of Chloride Concentration and Osmotic Pressure in the Crayfish Antennal Gland*
Authors: Riegel J. A. 
Published: April 2021

ABSTRACT
Chloride concentration and freezing-point depression (=osmotic pressure) have been measured on samples of urine obtained from various parts of the crayfish antennal gland by micropuncture. The chloride concentration of the urine is significantly below that of the blood in all parts of the antennal gland, but a marked drop is not seen until the distal tubule is reached. The urine becomes progressively hypo-osmotic to the blood in the labyrinth, distal tubule and bladder. In the coelomosac, it is iso-osmotic; possible reasons for this are discussed. Chloride concentration and osmotic pressure are lower in urine taken from the nephropore than in urine taken from the distal tubule near the place where it joins the bladder. This suggests that the bladder is in part responsible for the production of hypotonic urine. The results of the present study are discussed in relation to the theory that filtration (in the limited sense discussed by Riegel & Kirschner, 1960) is the mechanism by which primary urine is formed in the crayfish antennal gland.
Some Observations On the Actions of Steroids On the Metaplasia of the Amoeba, Naegleria Gruberi
Authors: Pearson Janet L. , Willmer E. N. 
Published: April 2021

ABSTRACT
The age of the culture of Naegleria gruberi, i.e. the time since the last subculture, is of little importance in determining the numbers of cells which turn flagellate when placed in the extremely dilute buffer solutions used. Between 17° and 21°C. there is a very great decrease in the time which the amoebae require in order to become flagellate when placed in buffer solution. There is no evidence that the amoeba, as such, differentiates between solutions of KCl or NaCl. On the other hand, the flagellate form is somewhat more reactive to KCl than to NaCl, and fewer flagellates are found in KCl solutions. The metaplasia is affected by the presence of steroids in the medium. The more interesting actions of the steroids tested may be summarized as follows. At high concentrations, progesterone and deoxycorticosterone, when applied to the amoeba, prevent the change to the flagellate form. When applied to the flagellate, progesterone has little action, but deoxycorticosterone encourages the return to the amoeboid form, especially in the presence of K+. In lower concentrations both steroids favour the change from amoeba to flagellate and also from flagellate to amoeba. Other steroids have characteristic effects. While the dose/response curves indicate qualitatively different effects of concentration of progesterone and deoxycorticosterone they only show quantitatively different effects with oestradiol and androsterone. Progesterone acts on amoebae at concentrations which are comparable with those at which it acts in the human body. When both progesterone and oestradiol are applied together at concentrations which suppress the flagellate form the effects are additive. The same applies to mixtures of testosterone and oestradiol. An activating concentration of progesterone has not yet been tested in combination with an inhibiting dose of oestradiol.
The Effect of the Web On Vibration Sensitivity in the Spider, Achaearanea Tepidariorum (Koch)*
Authors: Walcott Charles 
Published: April 2021

ABSTRACT
The common house spider, Achaearanea tepidariorum, has a sensitive vibration receptor in each of its eight legs. The receptor has been shown to respond to air-borne sound as well as to direct vibration (Walcott & Van der Kloot, 1959). But for a spider on its web a more usual source of information about the outside world comes from vibrations of the web strands themselves. What is the response of the receptor to the vibrations of the web? Liesenfeld (1956, 1961) has described some of the properties of spider webs and recorded the electrical response of the vibration receptors of a variety of species of spiders to vibrations of the substrate. Nowhere, however, can one find information on how vibrations of the web are translated by the spider’s vibration receptor into electrical impulses in the sensory nerve.
Contact Chemoreception, Mating Behaviour, and Sexual Isolation in the Rotifer GenusBrachionus
Authors: Gilbert John J. 
Published: April 2021

ABSTRACTMatings in two commonly co-occurring, limnetic species of the genus Brachionus, B. calyciflorus and B. angularis, are completely species-specific. Males initiate mating reactions only when they happen to swim head-on into females of their own species. In these reactions the male maintains contact with the female and simultaneously moves round and round her body until either he loses contact and swims away or he copulates. Females play an entirely passive role throughout the mating process. The male mating reaction is the manifestation of an innate reflex response which is triggered when certain coronal chemoreceptors make contact with, or are exposed to, a sudden, marked increase in concentration of a species-specific chemical substance located only in the females of the species. This substance, which is continually released into the environment by growing females and is extractable from crushed females with water, is: dialysable, ether-insoluble, heat-stable, acid-stable, base-labile, resistant to periodate oxidation, adsorbed on charcoal, amphoteric, and unaffected by trypsin, pepsin, and carboxypeptidase.
Frog Fast Muscle
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
A method is described for producing a family of curves of mechanical power output against tension, with time as parameter, in an isometric twitch. It is found that these differ from corresponding curves produced from the same muscle under isotonic conditions. A method is described of simulating a variable mass against which the muscle can contract. The time course during a twitch of the power expended in moving this mass, and of that expended in stretching the series compliance, is determined. In the early (‘active’) part of the twitch the total power agrees well with that predicted from isotonic measurements, but in the latter part (‘tail’) the muscle’s behaviour abruptly changes : it then resembles, with some differences, a large viscous resistance, in a manner which is compatible with the form of isometric twitches, but has no parallel under isotonic conditions. The power developed in certain phases of the isometric twitch falls short of that predicted from isotonic measurements. It is shown that this can be explained by postulating an upper limit to the rate at which the contractile component can develop tension, and supposing that this limit declines as the twitch proceeds.
The Landing Responses of Insects
Authors: Goodman Lesley J. 
Published: April 2021

ABSTRACT
The electroretinogram of Lucilia sericata has been recorded whilst the fly was stimulated by an approaching object and by a slow change of light intensity. The approach of a dark object against a light background was accompanied by the gradual development of a negative potential which decayed rapidly when movement ceased. The size of the potential change was found to be directly proportional to (a) the number of ommatidia stimulated by the approaching object, (b) the rate of the decrease and (c) the amount of the decrease of intensity which it produced. A similar response could be produced by stimulating the fly with a decrease of intensity, the negative potential developed being directly proportional to the number of ommatidia stimulated, to the rate and to the amount of the decrease.
Tactile Discrimination of Surface Curvature and Shape by the Octopus
Authors: Wells M. J. 
Published: April 2021

ABSTRACT
Experiments are described in which octopuses were trained to discriminate by touch between pairs of Perspex cylinders of different diameter. The proportion of errors made in experiments with thirteen different pairs of cylinders shows that octopuses distinguish cylinders on a basis of the difference in their surface curvature. Curvature is detected from the degree of distortion of individual suckers. The bend of the arm or arms grasping an object can be shown to be irrelevant by using composite cylinders built up from narrower rods. These are treated as being of the diameter of their components. Having been trained to take the larger and reject the smaller of two cylinders, octopuses tested with rough and smooth objects of the same size reject the rough and accept the smooth. Apparently the sensory input produced by contact with an object having a rough surface is similar to that produced by bending the suckers round a smooth curve of narrow radius. The discrimination of cubes and spheres, which appears to be based on sucker distortion at the corners of the cube, is upset by cutting grooves into the surfaces of the two objects. These findings are discussed in relation to the anatomy of the sense organs in the suckers. The development of two parallel mechanosensory systems, one related exclusively to the local adjustment of muscle tension, the other more concerned with the animal’s relations to its external environment and hence involved in learned responses, is common to the organization of cephalopods and vertebrates.
Osmotic Balance in Hydrobia Ulvae and Potamopyrgus Jenkinsi (Gastropoda: Hydrobiidae)
Authors: Todd Mary E. 
Published: April 2021

ABSTRACT
Osmotic balance was studied in Hydrobia ulvae and Potamopyrgus jenkinsi over the range 100% sea water to fresh water, by determining the freezing-point depression of the urine in the different solutions. Hydrobia ulvae was slightly hyperosmotic from 100 to 50 % sea water, and sometimes initially markedly hyperosmotic in 25 % sea water at 5° C. The urine was always markedly hyperosmotic relative to fresh water, and the animals were withdrawn. Experiments with phenol red indicated that the tissues were not shut off from the medium. Potamopyrgus jenkinsi was hyperosmotic from fresh water to 100% sea water. Osmotic balance in fresh water is maintained in part by the excretion of a urine hypo-osmotic relative to the blood. There was some variation in the reaction of different ecological groups of Hydro-bia ulvae and Potamopyrgus jenkinsi to the experimental conditions. In the Hydrobiidae, whether transformed from a lower to a higher salinity or vice versa, survival outside the viable range was longer at 5° C. than at 15° C., although, within the range, activity occurred more rapidly at 15° C. In fresh water, winter animals of both species had a higher osmotic concentration of the urine than summer animals, but no differences in osmotic concentration correlated with temperature were demonstrated.