bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potassium Movements in A Central Nervous Ganglion of Limnaea Stagnalis (L.) (Gastropoda : Pulmonata)
Authors: Sattelle D. B. 
Published: April 2021

ABSTRACT
Resting potentials and action potentials recorded from in situ, intact and desheathed giant neurones of the right parietal ganglion of Limnaea stagnalis are of similar magnitude. Ganglionic potential profiles reveal the absence of a sheath potential. It is concluded that the extra-neuronal fluid has a similar ionic composition to the blood (bathing medium). A 34 mV decade potassium slope is obtained for both intact and de-sheathed neurones. Depolarization of the neuronal membrane takes place rapidly in intact preparations, and the de-sheathing procedure significantly increases the rate of depolarization. A reduction in temperature from 23 to 8 °C only slightly prolongs the time-course of depolarization of an intact neurone. When the concentration of potassium in the fluid bathing the surface of an intact ganglion is elevated, the concentration of this cation at the neuronal surface changes exponentially with time. It is suggested therefore that diffusion along the extracellular channels is the mechanism and pathway for the movement of potassium ions through the right parietal ganglion of Limnaea stagnalis.
Humoral Regulation of the Cerebral Neurosecretory System of Rhodnius Prolixus (Stal.) During Growth And Moulting
Authors: Steel C. G. H. 
Published: April 2021

ABSTRACT
In normal fifth instar Rhodnius the cytological changes occurring in the medial neurosecretory cells (MNC) of the brain are very different before and after the ‘critical period’ for decapitation. When a decapitated insect which has reached the ‘critical period’ (8 days after feeding) is joined in parabiosis to an insect with an intact cerebral endocrine system and which has not yet reached the ‘critical period’ (1 day after feeding) the MNC of the younger insect are induced to switch over from their normal sequence of cytological changes to those characteristic of the older insect. The induced changes do not occur in normal insects of the same age or in insects joined in parabiosis to others of the same age. The nature of the changes indicates that release of stainable neurosecretory material is inhibited and its synthesis stimulated by the older insect. It is inferred that the haemolymph of insects which have reached the ‘critical period’ contains a factor which induces in the MNC an inhibition of release and a stimulation of synthesis. These are the events which occur in the MNC of normal insects at the critical period. Considerable circumstantial evidence suggests that the factor is ecdysone. It may act either directly on the brain or on the corpus allatum. Its contribution to a feedback regulation of the endocrine system controlling growth and moulting is discussed.
Phototaxis in Limulus Under Natural Conditions: Evidence For Reception of Near-Ultraviolet Light in the Median Dorsal Ocellus
Authors: Lall Abner B. , Chapman Robert M. 
Published: April 2021

ABSTRACT
Phototactic behaviour in Limulus mediated by lateral eye and dorsal ocellus was studied under full-spectrum and restricted-spectrum (near-u.v. and visible light) sunlight on a beach. All eyes (lateral eyes, dorsal ocelli) were occluded excepting one, which mediated the response. It was found that either a lateral eye or a dorsal ocellus alone could mediate positive phototaxis in adult Limulus under full-spectrum sunlight. When the sunlight stimulating the dorsal ocellus was filtered into restricted wavelengths, the near-u.v., but not the visible light, elicited positive phototaxis.
Na+/NH4+, Na+/H+ Exchanges and NH3 Movement Across the Gill of Carassius Auratus
Authors: Maetz J. 
Published: April 2021

ABSTRACT
Sodium uptake from the external medium in the absence of permeant co-ion occurs in most freshwater animals. Exchange of Na+ for an endogenous cation is necessary to maintain the electroneutrality of the external and internal media.
An Electrophysiological Study of Neuroglandular Transmission in the Isolated Salivary Glands of the Cockroach
Authors: House C. R. 
Published: April 2021

ABSTRACT
Some aspects of neuroglandular transmission in isolated salivary glands of the cockroach have been studied. The membrane potential of acinar cells is – 32 ·3 ±0 ·8mV (mean ±S..E; N = 600 cells) when the gland is bathed in Ringer solution. Upon delivering a single shock by ‘field stimulation’ to the salivary nerves the gland cell membrane undergoes after an initial latency of 1 second a transient hyperpolarization of about 1 –30 mV which lasts for about 10 sec. When the salivary nerves are stimulated by trains of current pulses the hyperpolarization that occurs is larger in amplitude and longer in duration than that after a single stimulus. The amplitude of the responses to single shocks and stimulus trains depends on the external potassium concentration. Thus, the neurotransmitter may increase membrane permeability to potassium ions. The electrical response of the gland cell to 5-hydroxytryptamine in concentrations from 2 ·5 –250 × 10 −7M is similar in sign and magnitude to that of nervous stimulation. Occasionally small fluctuations in the membrane potential are observed and these are similar in sign and duration to responses elicited by single shocks to the salivary nerves.
The Mechanism of Rapid Running in the Ghost Crab, Ocypode Ceratophthalma
Authors: Burrows Malcolm , Hoyle Graham 
Published: April 2021

ABSTRACT
Ocypode ceratophthalma has a maximum speed of 2·1 m/sec when running on a measured track with a base of hard-packed sand. Speed increases linearly with the width of the carapace up to a certain size, beyond which larger crabs run slower than smaller ones. The crab does not run at these high speeds by making extremely rapid movements as these data seemed to require. The highest frequency of leg movements observed was 20 Hz. Electromyographs of muscles used in running, made from the freely running, intact crab, showed asymmetry in the motoneurone discharges. Extensors and flexors in the meropodites of legs on the leading side frequently showed only a maintained tonus and could not have contributed to the running movements. Those on the trailing side showed alternation synchronous with stepping. It is concluded that the crab mainly pushes itself along rather than using a push-pull combination. Three pairs of legs are commonly used in running. Legs 2 and 4 of one side move together with leg 3 of the opposite side and provide a tripod of support. At the highest speeds only legs 2 and 3 of one side are used to provide thrust alternately. The high speed is achieved by the crab leaping through the air as it steps, thereby increasing the effective length of the steps.
The Mechanics of the Growing Semicircular Canal
Authors: Kate J. H. Ten 
Published: April 2021

ABSTRACT
The motion of the endolymph in the semicircular canal is described with the aid of a linear second-order system, comprising the applied angular acceleration and the linear displacement, the linear velocity and the linear acceleration of the endolymph. A sensitivity factor G for angular velocity is derived and expressed in the dimensions of the semicircular canal. The sensitivity factor G of the semicircular canal proves to be consistent with the equivalent sensitivity factor of a more sophisticated hydrodynamic model of these canals. The sensitivity of the growing semicircular canal is defined to be , independent of the pike’s size. Threshold angular velocities for the vestibulo-ocular reflex of 27 pike between 4 and 50 cm bodylength are in agreement with this assumption. At threshold stimulation with an angular velocity of 2°/sec the radius of curvature Rc of the cupula is calculated to be 220 ± 48 cm. At the threshold angular velocity γ = 2°/sec the deviation of sensory hairs 5 μ m long is assessed to be between 0·06 Å and 1 Å. Young’s modulus of elasticity for the cupular substance is found to be between 0·35 × 103 dyne/cm2 and 1·85 × 108 dyne/cm2 (on the basis of a circular bending for the cupula). Characteristics of the model of the growing semicircular canal are calculated for pike with body length between 5 and 100 cm. Observed growth effects of the pike’s vestibulo-ocular reflex arc are correlated to the growth effects calculated on basis of the model for the growing semicircular canal. The pike possesses the same degree of vestibulo-ocular compensation in the high-frequency range (2 radians/sec = ⩽ ω&lt; 7 radians/sec) of angular oscillations during its whole life (11 observations of pike of body length 4–56 cm).
The Role of Calcium in the Action of 5-Hydroxytryptamine and Cyclic Amp on Salivary Glands
Authors: Prince William T. , Berridge Michael J. 
Published: April 2021

ABSTRACT
The role of calcium in the potential and secretory responses of isolated salivary glands of Calliphora to 5-HT and cyclic AMP has been studied. Secretion induced by 5-HT was reversibly inhibited by removal of calcium from the bathing medium. The chloride-dependent depolarization of the apical membrane produced by 5-HT was calcium dependent whereas the potential response to cyclic AMP was little effected. Strontium and barium effectively substituted for calcium. Manganese replaced calcium at the onset of secretory and potential responses but these responses were maintained when manganese was removed. Lanthanum did not substitute for calcium in secretory responses but did inhibit the secretory and potential responses to calcium in calcium-depleted glands. The rate of secretion in a low-chloride medium produced by cyclic AMP was significantly lower than that induced by 5-HT, but there was little difference in normal saline. A model for the mode of action of 5-HT is proposed in which calcium acts as an intracellular intermediary controlling chloride movements whilst cyclic AMP controls a potassium pump.
Progressive Decrements in the Activity of Aplysia Neurones Following Repeated Intracellular Stimulation: Implications for Habituation
Authors: Stephens Cathy Lamar 
Published: April 2021

ABSTRACT
Repeated intracellular stimulation of nuerones from the isolated abdominal ganglion of Aplysia californica produced progressive response decrements with parametric features common to trans-synaptic models of habituation. The probability that a constant intracellular pulse of depolarizing current would produce an action potential decreased with repeated stimulation, the response decrements developed with interstimulus intervals ranging from 2 to 10 sec. In all cases, the response decrements were reversible with prolonged rest. In some cases complete recovery did not occur for up to 20 min, which indicated that the spontaneous recovery process was long-term in nature. As is typical of parametric studies of habituation, short, rather than long interstimulus intervals, and a weak, rather than a strong stimulus, produced greater response decrements. These results demonstrate that an individual neurone shows response decrements as a function of repeated stimulation, which suggests that there are at least two processes responsible for the response decrements seen during trans-synaptic stimulation: (a) synaptic depression and (b) a depressive process originating in the post-synaptic neurone.
Properties of Stalk-‘Muscle’ Contractions of Carchesium Sp.
Authors: Rahat M. , Pri-Paz Y. , Parnas I. 
Published: April 2021

ABSTRACT
The stalk of Carchesium was found to contract in an ‘all or none’ fashion in response to electrical stimuli. Rise time and half-decay time of contractions were 40−60 msec and 800−900 msec respectively. Forces developed during contraction were between 400−800 g/cm2. At o·2 stimuli/sec or less, the stalk contracted at a one-to-one ratio. At higher rates of stimuli the stalk contracted at its own pace, indicating an intrinsic refractory system. No tetanic responses or summation were observed in normal stalks. In fatigued stalks, partial summation was obtained and relaxation time was increased. It is concluded that the contractile system of Carchesium is probably different from that of a metazoan muscle.
Impulse Activity and Pattern of Large and Small Neurones in the Cardiac Ganglion of the Lobster, Panulirus Japonicus
Authors: Tazaki Kenro 
Published: April 2021

ABSTRACT
The cardiac ganglion of the lobster, which contains five large and four small cells (Alexandrowicz, 1932), produces integrated patterns of burst discharges. Maynard (1955, 1966) described how this ganglion may be compared to a miniature central nervous system, and pointed out that integrative processes occurring within the ganglion are of great interest because analyses of a simple nervous system may be an approach to the study of integration in complex nervous systems. Electrophysiological investigations of these ganglion cells have been reviewed by Hagiwara (1961). Intracellular studies have been made in detail on large cells of Panulirus (Hagiwara & Bullock, 1957; Bullock & Terzuolo, 1957; Watanabe, 1958; Otani & Bullock, 1959; Hagiwara, Watanabe & Saito, 1959; Watanabe & Bullock, 1960; Tazaki, 1971b, 1972a). The conclusion concerning their activity is as follows: large cells (followers) are innervated by common presynaptic nerve fibres from small cells (pacemakers), and potential changes during the burst are several kinds of synaptic potentials and spikes. This conclusion is not, however, valid for the Homarus ganglion. Cooke (1966) and Connor (1969) have studied the intracellular activity of its large cells. Connor (1969) has concluded that potential deflexions are due toendogenous activity of the respective neurones and not to synaptic potentials.
Branchial Sodium Transport Mechanisms in Scyliorhinus Canicula: Evidence for Na+/NH4+ And Na+ H+ Exchanges and for A Role of Carbonic Anhydrase
Authors: Payan P. , Maetz J. 
Published: April 2021

ABSTRACT
Smith (1953) suggested that during the course of evolution, the transition between invertebrates and vertebrates occurred in the marine environment at the beginning of the paleozoic era. Much later, during the Silurian period, the hypothetical ‘Protovertebrates’ invaded brackish and fresh waters. In these media it is probable that their body fluids remained hyperosmotic to the external medium, although their osmolarity must have declined to a certain extent.
Effects of Ambient Temperature on Warm-Up in the Moth Hyalophora Cecropia
Authors: Bartholomew George A. , Casey Timothy M. 
Published: April 2021

ABSTRACT
The rates of pre-ffight warm-up in adult Hyalophora cecropia (mean weight 3·10 g) were measured 24−36 h after eclosion at 15, 20, 25, and 30 °C in still air.
The rate of thoracic warm-up increased linearly with ambient temperature, averaging 2.6 °C/min at 15 °C and 6.5 °C/min at 30 °C. Thoracic temperatures typically reached 37−39 °C while abdominal temperatures rarely rose more than 3 °C above ambient. The cooling curves of the thorax at 15°and 25°C were straight lines and had similar slopes on a semi-logarithmic plot. Our data are compatible with the idea that heat production is dependent on thoracic temperature, and are incompatible with the theory that it depends on the difference between thoracic and ambient temperatures.
Ion and Water Balance in the Ixodid Tick Dermacentor Andersoni
Authors: Kaufman W. R. , Phillips J. E. 
Published: April 2021

ABSTRACT
An in vitro method is described for stimulating the salivary gland of Dermacentor andersoni to secrete fluid. In vitro glands require the presence of a catecholamine for salivation to occur. Natural haemolymph from salivating ticks does not trigger secretion suggesting that the tick does not produce a‘salivation hormone’ analogous to the diuretic hormones of certain insects. Pilocarpine, glutamate and malate did not stimulate secretion in vitro. Isoproterenol and 5-hydroxytryptamine were relatively weak stimulants (threshold concentrations of approximately 10−5 M and greater than 10−4 M respectively). Adrenaline, noradrenaline and dopamine were highly effective stimulants, the threshold concentrations being no more than 10−6 M. Adrenaline could also elicit a copious secretion in vivo at a final haemocoele concentration of about 2 × 10−5 M. We postulate that salivation occurs by means of a secretory rather than a filtration-resorption mechanism. Control of fluid secretion is probably neural rather than hormonal, the transmitter substance being a catecholaminergic substance.
Bird Metabolism During Flight: Evaluation of A Theory
Authors: Tucker Vance A. 
Published: April 2021

ABSTRACT
Pennycuick’s (1969) theory for the energetic requirements of avian flight predicts the metabolic rates of budgerigars and laughing gulls flying level at intermediate speeds in a wind tunnel with an accuracy of 10% or better. However, its predictions appear to be low for most birds with masses less than 0·1 kg and high for most birds with masses greater than 0·5 kg. Four modifications are made to Pennycuick’s theory : (1) a different computation of induced power; (2) a different estimate of equivalent flat plate area that includes Reynolds number effects, and is based on additional measurements; (3) a different estimate of profile power that includes Reynolds number effects; and (4) the addition of power terms for respiration and circulation. These modifications improve the agreement between the theoretical predictions and existing measurements for flying birds and bats. The metabolic rates of birds and bats in level flight at various speeds can be estimated by the modified theory if body mass alone is measured. Improved estimates can be made if wing span is measured as well. In the latter case the theory predicts measured values with a mean absolute error of 8·3 %. The results of the modified theory are presented by approximate equations that can be solved quickly for metabolic rate and flight speed with a slide rule.
Mechanism of the Spermatophoric Reaction in the Giant Octopus of the North Pacific, Octopus Dofleini Martini
Authors: Hanson D. , Mann T. , Martin A. W. 
Published: April 2021

ABSTRACT
The spermatophoric reaction in the giant octopus requires 1-2 h, and during that time the large mass of spermatozoa contained in the proximal (male-oriented) portion of the spermatophore, is propelled over a metre-long distance to the distal (female-oriented) end. Osmotic pressure provides the main mechanism for the spermatophoric reaction; and the influx of sea water, as a result of which the intraspermatophoric fluid space increases fivefold, provides the main force for driving the spermatozoa from the proximal to the distal end of the spermatophore. The outer tunic of the spermatophore acts as a semipermeable membrane, permeable to sea water but not to macromolecular substances. Its strength is adequate to resist inside pressure 400 cm water in excess of the external environment. In the normal course of spermatophoric reaction intraspermatophoric hydrostatic pressure increases from about 140 cm water at the onset of the reaction to about 330 cm H2O at the moment when the cap of the spermatophore ruptures and the ejaculatory apparatus is extruded; the rate at which pressure increases during this phase of the reaction is about 8 cm H2O/min. Immediately after the extrusion of the ejaculatory apparatus the pressure falls precipitously. It then increases once more, but very slowly, reaching 45–95 cm H2O before the ejaculatory apparatus evaginates. It declines once more during the final stage of the evagination process. At the end of the spermatophoric reaction the transmural pressure is only about 9 cm H2O in the spermatophoric bladder but approximately 4 times higher in the proximal portion of the spermatophore.’ In spite of the increase in the concentration of sodium and chloride ions in the intraspermatophoric fluid, the osmolality of that fluid remains largely unaltered throughout the whole spermatophoric reaction, but always at a level distinctly higher than the surrounding water (by about 30 mOsm/kg water). Large-molecular glycoproteins in the spermatophoric plasma are probably undergoing enzymic breakdown by glycosidases during the spermatophoric reaction, as a result of which some carbohydrate, aminosugar and other nitrogenous organic material pass from the interior to the exterior of the spermatophore.
Acoustic Properties of the Cod Swimbladder
Authors: Sand Olav , Hawkins A. D. 
Published: April 2021

ABSTRACT
The resonance frequency and damping of the swimbladder were measured for intact living cod at different depths. At adaptation depth, the resonance frequency (fr) of the organ was much higher than that predicted for an unrestrained gas bubble of similar volume. However, at much greater depths (where the hydrostatic pressure was 2 or more times greater than the adaptation pressure) fr was only higher than expected by a factor of 1 · 25, and changed with depth in the manner of a free gas bubble. The elevated values at greater depths can be explained in terms of the difference in shape between the swimbladder and an ideal spherical bubble, together with a light effect from the surrounding tissues. We have calculated that the shear modulus of these tissues (μ1) has a value of approximately 1 · 7 × 106 dyne/cm2. However, we have suggested that the much higher elevation of fr found at the adaptation depth results from a large increase in μ1(by a factor of between 6 and 120). This increase may be the result of a maintained muscle tonus. There is an immediate drop in fr as a fish is moved to a new depth, but the elevated values are rapidly restored with time. This process of adjustment is too rapid to be accounted for by the restoration of the swimbladder to its former volume by the secretion or absorption of gas. It is possible that it is achieved by a muscular mechanism which restores μ1 to the former high value. Though the maintenance of fr at a high value may reflect mechanical processes concerned with the hydrostatic function of the swimbladder, or with the detection of static pressure changes, we suggest that it may also be of some value if the swimbladder is used as an accessory hearing organ. The maintenance of an fr well above the hearing range of the fish ensures that the relative sensitivity of the animal to different frequencies does not alter with changes in depth.
Physiology of Insect Ecdysis
Authors: Truman James W. 
Published: April 2021

ABSTRACT
Ecdysis of insects involves a series of behavioural and physiological processes which are concerned with the escape of the insect from the confining exuviae and the expansion and tanning of the new cuticle. Cottrell (1962a, b) and Fraenkel & Hsiao (1962) first reported that a blood-borne factor triggered the tanning of the cuticle of the newly emerged fly. This hormone, which was later termed bursicon (Fraenkel & Hsiao, 1965), is released after the newly emerged fly has dug its way out of the soil. In other insects bursicon secretion is more closely associated with ecdysis and occurs slightly before or during the shedding of the old skin (Cottrell, 1962 b;Fraenkel & Hsiao, 1965; Mills, Mathur & Guerra, 1965).