bluuebunny/crossref_metadata_2025_split huggingface dataset:
Volume Regulation and Solute Balance in the Nervous Tissue of An Osmoconforming Bivalve (Mytilus Edulis)
Authors: Willmer P. G. 
Published: April 2021

ABSTRACT
Mytilus edulis could be adapted to salinities between 25% and 125% under laboratory conditions, with complete ionic and osmotic conformity of the body fluids. Extracellular space, intracellular cation concentrations and water content were determined for the cerebro-visceral connectives of Mytilus adapted to either 100% or 25% salinity. These measurements suggested only a moderate degree of volume regulation (as indicated by relative cell hydration) and net losses of both potassium and sodium from the cells during acclimation to dilute sea water, although neither cation was reduced in proportion to the external concentrations. Measurement of actual volume changes during acute hyposmotic stress indicated a greater capacity for volume control in the 25 %-adapted connectives. However, these tissues also showed an increment of 11% in initial diameter, suggesting significant chronic swelling of the cells. Fine-structural studies of Mytilus nerve indicated that the apparent swelling of the dilute-adapted tissues resulted from a roughly threefold thickening of the ensheathing neural lamella due to the deposition of extra collagen-like fibrils, with the axons in fact showing negligible volume increase. The connectives thus appear to exhibit almost perfect volume regulation. To account for the conflicting estimates of volume regulating capacity, it is proposed that the cells are hyperosmotic to their environment at 25 % salinity, the hydrostatic gradient thus created being countered by the restraint imposed by the thickened neural lamella. Physical stresses on the excitable membranes of the nerve would thus be minimized, and electrophysiological functioning in dilute media would be facilitated.
Measurements of the Osmotic Concentrations of Stylet Sap, Haemolymph and Honeydew from An Aphid Under Osmotic Stress
Authors: Downing N. 
Published: April 2021

ABSTRACT
The osmoregulatory physiology of aphids is poorly understood, yet it is such small terrestrial insects that face the severest osmotic problems. The lack of progress in this field reflects not only the difficulty of working with insects of such a small size but also the difficulty of obtaining samples of the sap on which they feed.
Initiation, Maintenance and Modulation of Swimming in the Medicinal Leech by the Activity of A Single Neurone
Authors: Weeks Janis C. , Kristan William B. 
Published: April 2021

ABSTRACT
A neurone (designated cell 204) has been identified in the segmental ganglia of the leech which, when stimulated intracellularly in isolated nerve cords, reliably initiates and maintains the neuronal activity pattern characteristic of swimming. In a minimally dissected leech, cell 204 activity results in normal swimming movements. Cell 204 is an unpaired, intersegmental interneurone which is present in most, if not all, of the segmental ganglia. Horseradish peroxidase injections indicate that cell 204 has extensive arborizations in its own ganglion and sends an axon both anteriorly and posteriorly via Faivre’s Nerve. Cell 204 is normally quiescent, but during swimming activity becomes depolarized and produces impulse bursts in the ventral contraction phase of its own segment. Such activity is observed in every cell 204 in the nerve cord and is independent of the stimulus used to evoke the swimming episode. Activity in any cell 204 is sufficient for initiation and maintenance of swimming activity, whereas activity in any two of them is not necessary for swimming. During swimming activity, imposed increases in the impulse frequency of any cell 204 cause a decrease in the swim cycle period of the entire nerve cord. Tactile stimulation of the skin, which is an effective method of eliciting swimming episodes, excites cell 204. Our findings indicate that cell 204 may activate swimming in the intact leech.
Directional Sensitivity in A Crayfish Mechanoreceptive Interneurone: Analysis by Root Ablation
Authors: Flood Patricia M. , Wilkens Lon A. 
Published: April 2021

ABSTRACT
Within the hierarchy of sensory interneurones in the crayfish, individual cells exist which code specifically for directional components of waterborne stimuli. The caudal photoreceptor interneurone (CPR) exhibits this mechanoreceptive response pattern, in addition to its primary light response. However, despite some variability the CPR is bidirectional, responding to water currents in both rostral and caudal directions. The peripheral mechanoreceptive fields providing input to the CPR have been examined, using selective root ablation procedures. Receptors from the exopodite and from the distal portion of the telson are the primary sources of input, this being carried by the 2nd and 5th roots respectively of the caudal ganglion. Input from the ipsilateral roots is normally excitatory; input arising contralaterally has an inhibitory influence. Populations of mechanoreceptors presynaptic to the CPR appear to be segregated in terms of the directional information encoded by the CPR. Specifically, ablation of the 2nd ipsilateral root decreases caudal sensitivity predominantly, whereas ablation of the 5th ipsilateral root primarily decreases rostral sensitivity. Therefore, only primary sensory cells which originate from the exo-podite, and respond to caudal deflexions of the hair shaft, effectively excite the CPR. Similarly, only the sensory cells originating from the telson which are responsive to anterior deflexions appear to effectively excite the CPR.
Intracellular Oxidation-Reduction Studies
Authors: Chambers Robert , Cohen Barnett , Pollack Herbert 
Published: April 2021

ABSTRACT
In a number of studies on the reduction potentials of living tissues and cells, the method of immersing the material under investigation in solutions of oxidation-reduction indicators has found considerable employment. Under controlled conditions and with sufficient knowledge concerning the physico-chemical characteristics of the indicator systems, this method is of value for determining the magnitude of extracellular reduction potentials. Its use, however, for the determination of intracellular reduction potentials has been hampered by the lack, among other things, of knowledge concerning the penetrating power of the indicators into living cells. Results obtained from immersion experiments alone have proved to be inconsistent. An example of this is given by J. and D. Needham (1) who examined a series of indicators and showed that cells become coloured when immersed in solutions of indicators which should be reduced intracellularly, while they give no sign of coloration in solutions of other indicators which should remain oxidised. These authors recognised the discrepancy but did not examine it more thoroughly.
The Adaptation of Gunda Ulvae to Salinity
Authors: Weil E. , Pantin C. F. A. 
Published: April 2021

ABSTRACT
Gunda ulvae is a small triclad which lives in estuaries between tide marks. It is surrounded by a medium which normally varies from completely fresh water to undiluted sea water: to either of these extremes the worm may be exposed for several hours at each tide. An account of its environment has been given in the previous paper (Pantin, 1931). The worms survive many months in sea water in an aquarium, but will not survive indefinitely in fresh water.
A Sensitive Recording (Transpiration) Balance With A New Form of Electrically Operated Recorder
Authors: Jones W. Neilson 
Published: April 2021

ABSTRACT
A number of instruments for automatically registering the loss of weight of a plant during transpiration have been devised, the best known, perhaps, being those described by Ganong (1905) and by Blackman and Paine (1914). In both these instruments the experimental plant is placed on one pan of a special balance, equivalent weights are added to the other pan, and the balance is kept in equilibrium by the addition of known weights at intervals as required to compensate for the loss of water during transpiration, each addition being recorded by an electrical device.
The Senescence of Spermatozoa, II
Authors: Gray J. 
Published: April 2021

ABSTRACT
In a recent paper (Gray, 1928 a) the progressive loss of activity of a suspension of Echinus sperm was considered from two points of view; firstly, as a process of spontaneous and irreversible depletion of available energy and secondly, as a process of auto-intoxication whereby the products of activity inhibit the essential reactions of life. Both of these hypotheses led to a quantitative relationship between the total oxygen absorbed by a suspension and the period of time which had elapsed since the beginning of active life. This relationship was, in both cases, in harmony with that recorded by experiment, so that it is only possible to judge the relative merits of the two hypotheses by the intrinsic probability of the underlying assumptions, or by the provision of more specific data. An attempt to provide such data has proved detrimental to both theories.
Studies on the Pituitary
Authors: Hogben Lancelot , Charles Enid , Slome David 
Published: April 2021

ABSTRACT
The principal facts presented in this communication may be summarised as follows: Removal of the pituitary gland or of the anterior lobe alone results in involution of the ovaries, lowering of the serum calcium and cessation of skin secretion.Ovulation and skin secretion can be induced in Xenopus by injection of extracts of the pituitary gland.
This communication has raised a number of issues which would have been investigated more extensively if circumstances had not forced two of the authors to leave South Africa. It is therefore advisable to bring into sharper relief the two most important conclusions which are justified by the facts recorded.
The first of these is the very conclusive and complete evidence in support of the view that the anterior lobe of the pituitary controls the activity of the ovaries. Zondek and Ascheim (1927), Smith and Engle (1927), Bellerby (1930) and Parkes (1930) have shown that anterior lobe extracts or transplants stimulate the development of the ovaries in mammals. Unfortunately the removal of the pituitary gland in mammals is an operation of extreme difficulty. Conclusive evidence that the pituitary has a functional relation to the ovaries is lacking, unless the effects of operative removal can be brought into harmonious relationship with the effects of injection and implantation. In Xenopus it is possible to do this in a very striking manner. It is now therefore justifiable to assert that the results obtained by injection and implantation in mammals are not merely an indication of a new and specific pharmaco-dynamic constituent in the anterior lobe of the pituitary gland but of a genuine functional influence of the pituitary on the normal ovarian cycle. The new evidence presented in this communication reinforces a large volume of previous work on the comparative physiology of the ductless glands pointing to a widespread uniformity of endocrine phenomena within the vertebrate series.
The other conclusion of outstanding importance which emerges from the present study is the influence of the pituitary gland on calcium metabolism. This opens up a field for further research and it would be premature to discuss it except in a very tentative way. Although there is no evidence at present to indicate that the pituitary gland exerts its influence on calcium metabolism directly, two considerations indicate that the influence of the anterior lobe on serum calcium is independent of the ovary. One is a comparison of the figures given for the eyeless and seeing groups in Table II which summarises the data presented in Sections II and III. The other is that Mirvish and Bosman (1927) have shown that injection of ovarian extracts lowers the serum calcium of rabbits.
On the Physiology of Amoeboid Movement
Authors: Pantin C. F. A. 
Published: April 2021

ABSTRACT
A
The action of isotonic sucrose, glucose, glycerol and urea on a marine amoeba has been studied. Experiments were performed with these to elucidate the action of calcium on locomotion. No movement occurs in these pure nonelectrolytes. The amoebae have remarkable powers of survival in pure isotonic nonelectrolytes (1·05 M). Survival ranges from 1 hour in the sugars to over 16 hours in the urea. Survival in the latter is far longer than in any other pure solution, including salts. Even when the concentration is as low as 0·04 M, the sugars tested inhibit movement in solutions which normally support it. Addition of calcium to glycerol does not support movement. But an optimum mixture of NaCl + CaCl2 which supports movement will suffer at least 75 per cent, dilution with isotonic glycerol and yet maintain movement. The addition of calcium to urea allows good movement over a wide range of low calcium concentrations: movement at the optimum is maintained for over 12 hours. The addition of urea to optimal mixtures of NaCl + CaCl2 necessitates the further addition of calcium to balance the effect of the added urea. The rôle of calcium in the external medium in relation to movement is reviewed. The physiological action of urea in these amoebae is compared with its action on many cells. It is suggested that the long survival and continued movement in the presence of urea is related to the maintenance of a condition of impermeability to dissolved substances at the cell surface. It is pointed out that this is in agreement with the denaturing action of urea in strong solutions on proteins. The possible significance of this in the adaptation of cell surfaces to a freshwater environment is mentioned.
B
An attempt has been made to determine the iso-electric point of the proteins of a marine amoeba by staining with methylene blue and eosine after fixation in alcohol. There appears to be a fairly definite iso-electric point between pH 4·6 and 5·0. This is at a considerable distance on the acid side from the pH at which movement is inhibited in the amoebae. It is suggested that sol ⇌ gel changes accompanying amoeboid movement cannot be related simply to the external H-ion concentration in a manner comparable to the relation of the latter to the properties of simple protein systems around the iso-electric point.
The Effect of Oestrin on the Testis of the Adult Mouse
Authors: Allanson Marjorie 
Published: April 2021

ABSTRACT
Two groups of adult male mice were injected daily with 340 m.u. of an aqueous solution of crystalline oestrin for fifteen days and twenty-one days respectively. Matings with these injected mice were fertile. The testis showed no degenerative changes, spermatogenesis being active in the large majority of seminiferous tubules. The diameter of the tubules showed no decrease in size. The epididymis was distended with spermatozoa. The anti-masculine effects obtained by previous workers have not been confirmed.
The Physiology of Excretion in a Blood-Sucking Insect, Rhodnius Prolixus (Hemiptera, Reduviidae)
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
An adult Rhodnius will ingest from two to three times its weight of blood at a single meal, and about three-quarters of the water in this blood is excreted as a clear fluid during the next three or four hours.
This fluid is alkaline (pH 7·8), more or less isotonic with the blood (sp. gr. 1·007; Δ = 0·62–0·68), and serves for the elimination of most of the sodium and potassium chlorides in the meal. It also contains urea, bicarbonate, sulphate and uric acid.
After the first day, the urine gradually becomes acid (pH 6·0–6·5) and much more concentrated, and contains a yellow pigment. Uratic spheres appear and increase in number until the urine is semi-solid. The urine now contains only traces of sodium, potassium, chloride and urea. There are small amounts of calcium, magnesium, phosphate, sulphate, creatine and probably amino acids. There is never any ammonia.
Almost all the nitrogen is excreted as uric acid. This is in the form of minute spheres with radial striation, in which about 80 to 90 per cent, of the uric acid is free ; the rest, presumably, as sodium and potassium acid urate.
The Physiology of Excretion in A Blood-Sucking Insect, Rhodnius Prolixus (Hemiptera, Reduviidae)
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
The excretory system of Rhodnius consists of four Malpighian tubes discharging into the rectum. Each tube consists of two segments :
An upper (distal) segment, comprising two-thirds of the tube, made up of very granular epithelium, and with only clear fluid in the lumen. The striated border of this segment is a rigid structure of the type called “honeycomb border” (“Wabensaum”). A lower (proximal) segment, comprising one-third of the tube, in which the epithelium is almost free from granules and the lumen filled with uratic spheres. The striated border of this segment is a typical “brush border” (“Bürstensaum”).
Below, each tube opens into the gut by way of a button-like ampulla. The four ampullae are lined by large cells which send long processes into the rectum; and around their opening is a zone of large cells, in the wall of the rectum, which constitutes a rectal gland.
After feeding, all the tubes are distended and clear while the watery urine is being excreted. Apart from this temporary distension, the cells of the upper segment show no definite changes. But the filaments of the striated border of the lower segment become very elongated, and, when the passage of the watery urine has ceased, uratic granules appear among them in increasing numbers. Later, these filaments retract, and the granules become free in the lumen.
The processes of the ampulla cells extend far into the rectum during excretion, and float in the fluid urine. Later they retract again.
Well-marked “vesicular secretion” is visible in sections of the Malpighian tubes, as well as in isolated tubes in Ringer’s solution, but it is shown that, in Rhodnius, these changes are artefacts.
Morphology of Identified Neurones in the Buccal Ganglia of Lymnaea Stagnalis
Authors: Benjamin P. R. , Rose R. M. , Slade Carole T. , Lacy M. G. 
Published: April 2021

ABSTRACT
The morphology of seven types of identified neurones in buccal ganglia of Lymnaea was investigated by intracellular injection of Procion Yellow and retrograde injection of cobaltous chloride into the nerve roots of the buccal ganglia. The results provided anatomical support for the electrophysiological findings that some cells are motoneurones for muscles of the buccal mass (type 4-group cells, types 6 and 8 cells). Others project to nerves innervating oesophageal tissue (types 2, 3 and 5 cells) and to pro-oesophageal tissue (types 3 and 5 cells). The type-i cells project to the salivary gland ducts and are similar to the salivary gland motoneurones found in other molluscan species.
Anatomy of the Regional Differences in the Eye of the Mantis Ciulfina
Authors: Horridge G. A. , Duelli Peter 
Published: April 2021

ABSTRACT
In the compound eye of Ciulfina (Mantidae) there are large regional differences in interommatidial angle as measured optically from the pseudopupil. Notably there is an acute zone which looks backwards as well as one looking forwards. There are correlated regional differences in the dimensions of the ommatidia. The following anatomical features which influence the optical performance have been measured in different parts of the eye: (a) The facet diameter is greater where the interommatidial angle is smaller. This could influence resolving power, but calculation shows that facet size does not exert a dominant effect on the visual fields of the receptors. (b) The rhabdom tip diameter, which theoretically has a strong influence on the size of visual fields, is narrower in eye regions where the interommatidial angle is smaller. (c) The cone length, from which the focal length can be estimated, is greater where the interommatidial angle is smaller. Estimation of the amount of light reaching the rhabdom suggests that different parts of the eye have similar sensitivity to a point source of light, but differ by a factor of at least 10 in sensitivity to an extended source. There is anatomical evidence that in the acute zone the sensitivity has been sacrificed for the sake of resolution. Maps of the theoretical minimum fields of the photoreceptors, plotted in their positions on the eye in angular coordinates, suggest that there are too few ommatidia for the eye as a whole to reconstruct all the visual detail that the individual receptors can resolve. The conclusion from (3) and (4), together with some behavioural evidence, suggests that the eye structure must make possible the resolution of small movements of contrasting edges and of small dark contrasting objects but there is less emphasis on the total reconstruction of fine patterns because the interommatidial angle is greater than the estimate of the acceptance angle.
Body Temperature and Singing in the Bladder Cicada, Cystosoma Saundersii
Authors: Josephson R. K. , Young D. 
Published: April 2021

ABSTRACT
Body temperatures during singing were measured in the cicada, Cystosoma saundersii Westwood, both in the field and in tethered animals indoors. The temperature of the sound-producing tymbal muscle rises rapidly during singing to reach a plateau approximately 12 °C above ambient. This produces a temperature gradient in the abdominal air sac which surrounds the muscle. When singing stops, the tymbal muscle cools exponentially. Heat production during singing, estimated from the cooling curve, is 4·82 cal min−1 g muscle−1. Generation of the same temperature excess in the air sac by an artificial heat source yields an estimated heat production of 54·4 cal min−1 g muscle−1. This discrepancy may be caused by air mixing in the air sac during singing. As temperature rises, tymbal muscle twitch contractions become faster and stronger. This and heat transfer to the thorax cause changes in the song pattern: a marked decrease in the interval between the two sound pulses produced by a single tymbal buckling and a lesser decrease in the interval between bucklings. The fundamental sound period remains unaltered. These effects are consistent with earlier data on sound production.
Synaptic and Hormonal Modulation of A Neuronal Oscillator: A Search for Molecular Mechanisms
Authors: Levitan Irwin B. , Harmar Anthony J. , Adams William B. 
Published: April 2021

ABSTRACT
The central ganglia of a number of gastropod molluscs (including the marine snail Aplysia californica and the terrestrial snail Helix pomatia) contain neurones which exhibit endogenous patterns of oscillatory activity. This oscillatory activity can be modulated for long periods of time by synaptic and hormonal stimulation. Stimulation of appropriate pre-synaptic nerves causes long-lasting hyperpolarization in these neurones, with complete abolition of oscillatory activity. This synaptic response is mediated by an increase in K+ conductance, together with a decrease in inward (Na+/Ca2+) conductance. The ionic conductances affected by synaptic stimulation are those responsible for producing the rhythmic oscillations. The oscillatory activity can also be modulated by the vertebrate neurohypophyseal peptides, vasopressin and oxytocin, and by an endogenous peptide-containing extract of molluscan ganglia. In contrast to synaptic stimulation, these agents cause an increase in oscillatory activity. The endogenous molluscan factor which produces an increase in oscillatory activity can be purified by affinity chromatography on bovine neurophysin linked to Sepharose. This indicates that the molluscan nervous system may contain a neurohypophyseal-like peptide. Oscillatory activity can be modulated by manipulation of cyclic nucleotide metabolism in these neurones. Increases in cAMP alone are associated with abolition of oscillatory activity; this mimics long-lasting synaptic hyperpolarization. Increases in cAMP and cGMP together are associated with an increase in oscillatory activity and mimic the effects of the vertebrate and molluscan peptides. Thus, it is possible that cyclic nucleotides play a role in these physiological responses.