bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activity in the Locust Nerve Cord in Response to Wing-Nerve Stimulation
Authors: Gettrup Erik 
Published: April 2021

ABSTRACT
Nerve cord activity in response to repetitive stimulation of wing nerves 1C1 and 1D was investigated in preparations of locusts. Firings of single central units occurred at latencies defined with an accuracy of few milliseconds. Various recordings of latencies show that it is not possible to exclude ganglionic synapses within the pathways considered. Records from the connectives anterior to the mesothoracic ganglion or from the abdominal connectives show an increase in activity during repetitive stimulation. When recorded between prothoracic and mesothoracic ganglia a response was found in ipsilateral as well as contralateral connectives. The ipsilateral and contralateral responses were delayed differently with respect to the stimulus. When nerve 1C1 of metathorax was activated the ipsilateral delay amounted to 7 msec., s.d. 2 msec., whereas the contralateral delay was found to be 8 msec., s.d. 3·4 msec. Ipsi- and contralateral latencies during stimulation of 1D of the metathorax were 5 msec., s.d. 1·4 msec.
A Quantitative Analysis of Ciliary Movement by Means of High-Speed Microcinematography
Authors: Baba Shoji A. , Hiramoto Yukio 
Published: April 2021

ABSTRACT
An optical arrangement for high-speed microcinematography has been designed so as to record ciliary movement, and the movements of single large abfrontal cilia of Mytilus gill have been photographed at 400–500 frames/sec. with brief exposures of 1/20,000 sec. A quantitative description of the movement of the cilium is presented in terms of the changes of the curvature at various regions of the ciliary shaft and of the change of the basal angle. The principle of the description mentioned above is also applied to the movement of the cilium in media of high viscosities, and some parameters of the movement (duration, amplitude of the basal angle, maximum curvature and propagation velocity of the bending wave) are presented. The resistance experienced by the cilium during its beating has been evaluated under some hydrodynamic assumptions, and the flow induced by the cilium and the bending moment of the ciliary shaft due to the viscous resistance have been calculated over a single beat. The change of the degree of bending of the ciliary shaft (curvature) takes place in advance of the change of the bending moment at the same region in the distal as well as in the proximal regions of the ciliary shaft. This fact indicates that active processes are involved in bending and unbending of the ciliary shaft during its beat.
Urea and Osmoregulation in the Diamondback Terrapin Malaclemys Centrata Centrata (Latreille)*
Authors: Gilles-Baillien M. 
Published: April 2021

ABSTRACT
The blood of the diamondback terrapin going from fresh water to 50% sea water shows an increase in its osmotic pressure which is mainly due to an increase in Na and Cl concentrations. The blood of terrapins living in sea water compared with the blood of terrapins living in 50 % sea water shows a higher osmotic pressure which is the result solely of a higher urea concentration; Na and Cl concentrations are no longer affected in this second stage of adaptation. Urine of 50% sea-water terrapins and of sea-water terrapins is generally isosmotic to the blood while the urine of fresh-water terrapins is usually hypo-osmotic. The bladder appears to play an essential part in reducing water loss in the seawater terrapins but is not implicated in the salt balance. When each animal is considered individually, the urea concentration in the urine is always higher than in the serum, suggesting that the high urea concentration in the blood of terrapins adapted to sea water is due to an urea accumulation in the bladder.
Hypo-Osmotic Urine in Nereis Diversicolor
Authors: Smith Ralph I. 
Published: April 2021

ABSTRACT
Although Beadle as early as 1937 suggested that the urine of Nereis diversicolor O. F. Müller might be of lower concentration than the body fluids when this worm is hyperregulating in low salinities, there has been no direct measurement of urine concentration to support this reasonable idea. Jørgensen & Dales (1957) studied osmotic water uptake and loss in N. diversicolor and calculated that this animal reduces its permeability to water by over 60% when in fresh water. On the assumption that chloride permeability was comparably reduced, they calculated that the observed rate of chloride exchange and the level of chloride concentration in the coelomic fluid were compatible with the production of a small volume of urine isotonic in chloride to the body fluid. However, Potts & Parry (1964) in reviewing this matter regarded the evidence of Jørgensen & Dales for reduced permeability to water as not well founded and, without presenting new data but by making the assumption that no changes in permeability occurred, drew up a balance-sheet for chloride exchanges which led them to postulate a reduction of chloride loss in low salinities by production of an hypotonic urine. Although there is no incompatibility between reduction of chloride loss by reduction of permeability to water (and hence urine volume) and by resorption of chloride from a consequently hypotonic urine, the fact that different authors can postulate these as alternative mechanisms on the basis of the same data makes it evident that measurements of urine concentration and volume would be useful in further attempts at analysis of the regulation of chloride and water in N. diversicolor. In a preceding paper (Smith, 1970a) there has been shown a correlation between chloride loss and weight loss compatible with the production of hypotonic urine by this species at low salinities, but this evidence is not conclusive. It has further been shown (Smith, 1970b) that N. diversicolor reduces its apparent permeability to water (as D2O) in low salinities, which seems to confirm the view of Jørgensen & Dales (1957), but the urine volumes calculated were such as to make it probable that chloride resorption and production of a urine hypotonic in chloride to the body fluid can also take place.
Sodium Regulation in the Freshwater Mollusc Limnaea Stagnalis (L.) (Gastropoda: Pulmonata)
Authors: Greenaway Peter 
Published: April 2021

ABSTRACT
Sodium regulation in normal, sodium-depleted and blood-depleted snails has been investigated. Limnaea stagnalis has a sodium uptake mechanism with a high affinity for sodium ions, near maximum influx occurring in external sodium concentrations of 1·5–2 mM-Na/1 and half maximum influx at 0·25 mM-Na/1. L. stagnalis can maintain sodium balance in media containing 0·025 mM-Na/1. Adaptation to this concentration is achieved mainly by an increased rate of sodium uptake and a fall of 37% in blood sodium concentration, but also by a reduction of the sodium loss rate and a decrease in blood volume. A loss of 23% of total body sodium is necessary to stimulate increased sodium uptake. This loss causes near maximal stimulation of the sodium uptake mechanism. An experimentally induced reduction of blood volume in L. stagnalis increases sodium uptake to three times the normal level. About 40% of sodium influx from artificial tap water containing 0·35 mM-Na/1 into normal snails is due to an exchange component. Similar exchange components of sodium influx were also observed in sodium-depleted and blood-depleted snails in the same external sodium concentration.
The Central Course of the Hair Afferents and the Pattern of Contralateral Activation in the Central Nervous System of the Scorpion, Heterometrus Fulvipes
Authors: Sanjeeva-Reddy P. , Rao Kandula Pampapathi 
Published: April 2021

ABSTRACT
As in the crustaceans and insects, so in the scorpion the primary afferent fibres constitute a considerable proportion of the axons in the central connectives. The possibility of a sensory neurone sending collaterals, while passing through a ganglion, which activate a contralateral interneurone has been conclusively demonstrated. This type of activation differs from the pattern of contralateral activation so far demonstrated in the insects and crustaceans. In the latter groups, the available evidence indicates the activation of contralateral interneurones by the terminal branches of the sensory axons, but not by the collaterals. It has been emphasized that in the scorpion, but not in insects and crustaceans, the tactile input from a single hair is adequate to trigger the central responses, which in itself is an advantage in analysing the integrative processes and functional connexions between neurones.
The Role of 5-Hydroxytryptamine and Cyclic Amp in the Control of Fluid Secretion by Isolated Salivary Glands
Authors: Berridge M. J. 
Published: April 2021

ABSTRACT
Isolated salivary glands of Calliphora have been used as a system on which to study the mode of action of a hormone. Cyclic AMP, which is thought to mediate the action of many different hormones, can stimulate fluid secretion equally as well as 5-HT. Methyl xanthines, which inhibit the hydrolysis of intracellular cyclic AMP by phosphodiesterase, can stimulate secretion and prolong recovery time after removal of 5-HT. Methyl xanthines can sensitize salivary glands to both 5-HT and cyclic AMP. Butyryl derivatives of cyclic AMP can stimulate secretion, but their effect is slower and lasts longer. Certain amino acids and malate support fluid secretion more effectively than trehalose or glucose. It is concluded that cyclic AMP plays an important role in the ability of 5-HT to control fluid secretion by salivary glands.
Modifications in the Automatic Diver Balance Technique
Authors: Bergfors T. , Mild K. H. , Løvtrup S. 
Published: April 2021

ABSTRACT
The automatic electromagnetic diver balance, described by Larsson & Løvtrup (1966), is based on the principle that a diver with density less than the surrounding medium is prevented from rising to the surface by an electromagnetic force acting on a small piece of iron placed in the diver. Since it was first introduced, the balance has displayed certain imperfections which have hampered experimental progress. The primary causes of these disturbances have been traced to temperature oscillations in the flotation medium, to details in the electronic design and to the magnetic materials used in the core and in the diver. In the course of the work to remedy these sources of trouble our understanding of the theory of the method has greatly improved and as a consequence we have been able to devise other innovations which enhance the precision of the method. This report presents in brief outline the theory and the various modifications introduced.
Ionic Content of Haemolymph in the Cockroach, Periplaneta Americana
Authors: Pichon Y. 
Published: April 2021

ABSTRACT
The haemolymph of the American cockroach, Periplaneta americana, has been analysed for Na+, K+ and Ca2+ ions in different experimental conditions. The ionic content of the haemolymph is maintained constant after the first larval instar. It is characterized by a rather high K+ level and a particularly large variability which could be related either to the nature of the diet (lettuce) or to numerous alterations of the blood and tissues in relation to the moulting cycle. The regulation of this ionic content when the animal is given different diets is particularly effective. Starvation results in a decrease in the mean ionic concentration in the blood, this decrease following a pronounced increase of the Na+ and K+ levels when starvation is associated with dehydration. The blood K+ level can be raised artificially with high K+ diets (lettuce leaves or high K+ saline) but is then very variable. These results are discussed in terms of absorption, excretion and storage mechanisms. The analysis of blood samples collected successively from the dorsal thorax of different individuals shows that, when the animals are fed normally, the ionic composition varies widely, showing that in these conditions the haemolymph is not homogenous. Serial measurements of blood ions in different regions of the animal show unequal distribution of Na+, Ka+ and Ca2+. This result is discussed in view of the very special circulatory system of insects when compared with that of vertebrates. The overall picture of insect blood which can be drawn from these experiments is that the complexity of the regulatory system together with the fact that the circulatory system is open and lacunous allows relatively wide variations in the ionic concentration to occur on both sides of a genetically fixed mean. This particular feature must be taken into account when one considers the physiological role of blood ions in mechanisms such as excitation, conduction or muscular contraction.
The Visual Mechanisms of Tenebrio Molitor: Some Aspects of the Spectral Response
Authors: Yinon U. 
Published: April 2021

ABSTRACT
The spectral responses of a ‘stored product’ insect, Tenebrio molitor, have been studied electrophysiologically. Although primarily inhabiting a darkened environment the insect possesses a visual mechanism which could enable it to discriminate various wavelengths. The visible range for T. molitor lies between &lt;350 and 700 mμ; and the efficiency and sensitivity curves both have maxima between 520 and 550 mµ. Latency and amplitude also indicate maximum response in this same region of the spectrum. Under normal conditions of dark adaptation the screening pigment does not affect the spectral sensitivity. Miniature threshold potentials concealed in the normal background noise were detected by the use of the computer of average transients. The two principal components of the ERG, as well as minor components which were occasionally detected, were similarly related to wavelength. This seems to imply that the various ERG components originate in receptors of one single type.
Effects of Sub-Lethal High Temperature On an Insect, Rhodnius Prolixus (Stål.)
Authors: Okasha A. Y. K. 
Published: April 2021

ABSTRACT
The reproductive activity in both sexes is completely inhibited during the exposure of adults to 34°C immediately after feeding. The changes that take place in the reproductive system in males and females during exposure parallel those brought about by starvation or allatectomy. Females exposed for 6 days to 34°C immediately after feeding, then decapitated and placed at 28°C, fail to form eggs, while those left with the head intact form mature eggs. The course of oxygen consumption of normal males and females is compared with that of insects placed immediately after feeding at 34°C and their respiration measured at the same temperature. It seems that the corpus allatum is not active at high temperature, or if active its hormone is ineffective. It is suggested that it is the synthesis of specific adult proteins which is interfered with by high temperature, hence the inhibition of the reproductive activity.
Chloride Regulation at Low Salinities by Nereis Diversicolor (Annelida, Polychaeta)
Authors: Smith Ralph I. 
Published: April 2021

ABSTRACT
The ability of the common brackish water polychaete worm Nereis diversicolor O. F. Müller to regulate osmotically and ionically has been well established (Schlieper, 1929; Beadle, 1937; Smith, 1955; Hohendorf, 1963; Oglesby, 1970; and others). Jørgensen & Dales (1957) demonstrated an uptake of chloride against the concentration gradient at low salinities, with a maximum rate of exchange under steady-state conditions at external chloride concentrations of 65–120 mM/I, and a drop in uptake rate to about one-third of that maximum in fresh water (Cl = 1·4mM/l). Fretter (1955) demonstrated a comparable uptake of sodium against the concentration gradient in this species, but without the maximum shown in the chloride exchanges.
Aspects of the Physiology of Terrestrial Life in Amphibious Fishes: II. The Chilean Clingfish, Sicyases Sanguineus
Authors: Gordon Malcolm S. , Fischer Siegmund , Tarifeño S. Eduardo 
Published: April 2021

ABSTRACT
A study has been made of major aspects of the physiological adaptations for terrestrial life possessed by the amphibious clingfish, Sicyases sanguineus, on the coast of central Chile. These fish can survive for more than 112 days out of water, if not exposed to severe dehydration or thermal stresses. Rates of evaporative water loss while out of water are low. Upper lethal temperatures are also low, reflecting the uniformly cool water temperatures of their environment. In nature the fish rarely leave areas in which they are frequently washed over by waves. These fish demonstrate an unusual combination of metabolic and cardiovascular adjustments to emersion. Metabolic rates (oxygen consumption) of small (1–5 g weight) fish are higher out of water than in water. Larger fish show a pattern of intermittent oxygen uptake when out of water. Heart rates respond to emersion (and associated cessation of breathing movements) in the pattern of the diving syndrome. Lactic acid concentrations in the blood gradually increase above control levels during the first few hours of emersion, then remain constant at about × 3 control level. There is no indication of peripheral vascular shutdown during emersion. Emersion produces a marked shift towards ureotelism in waste nitrogen production. There appears to be no systemic accumulation of ammonia during emersion. The generality of the results, and also their physiological significance, are discussed.
The Control of Water Loss in Desert Tenebrionid Beetles
Authors: Ahearn Gregory A. 
Published: April 2021

ABSTRACT
Total water loss in tenebrionid beetles was composed of transpiratory losses from the cuticle and spiracles, water associated with defaecation, and water from the release of defensive quinone droplets or oral fluids. Freshly killed specimens of E. armata, C. muricata and C. verrucosa had higher transpiration rates over long and short exposures than did living animals of the same species. These results may reflect the cessation of active water retention by cuticular and spiracular regulation in dead animals. Cuticular transpiration, although low in absolute rate, was a greater source of water loss than respiratory transpiration in E. armata, C. muricata and C. verrucosa at temperatures from 25 to 42·5°C and at 0% R.H., suggesting that spiracular control of water loss was of considerable importance in maintaining water balance. A marked increase in respiratory transpiration over previous low rates was observed at 40°C for E. armata and at 42·5°C for C. muricata and C. verrucosa, and indicated a temperature-induced breakdown in spiracular water regulation due to increased respiratory activities. In contrast, cuticular transpiration maintained a linear rate of increase over the temperature range investigated. A direct relationship existed between oxygen consumption and estimated respiratory transpiration for E. armata from 25 to 40°C and at 0% R.H. Evidence for the presence of discontinous respiration and unidirectional tracheal air flow in E. armata was presented. Cuticular transition temperatures were measured for E. armata (40°C), C. muricata (47·5°C), and C. verrucosa (50°C) with results showing that the autumn species (E. armata) possessed a lower cuticular breakdown point than either of the two summer species. Much of the success of tenebrionid beetles in desert habitats is due to the development of highly impermeable cuticles and well regulated spiracular control mechanisms for reducing the loss of body water.
Temperature Dependence of the Neural Control of the Moth Flight System
Authors: Hanegan James L. , Heath James Edward 
Published: April 2021

ABSTRACT
The transition from the warm-up motor pattern to the flight motor pattern in the saturnid moth H. cecropia, is described. The transition from warm-up to flight was found to be dependent on the temperature of the thoracic ganglia. A model to account for the two different motor output patterns and the transition of the warm-up pattern to the flight pattern is proposed.
Active Transport of Caesium by the Isolated and Short-Circuited Midgut of Hyalophora Cecropia
Authors: Zerahn Karl 
Published: April 2021

ABSTRACT
The short-circuited midgut from the larvae of Hyalophora cecropia can actively transport potassium and rubidium from blood side to lumen. In this paper it is demonstrated that caesium also can be actively transported. Transport of potassium does not interfere with the metabolism of the midgut; nor does transport of caesium. Potassium and rubidium compete for the transport mechanism in a one-to-one ratio but competition between potassium and caesium is more complicated. At high caesium:potassium ratios the active transport taking place is transport of caesium; when the ratio is 2 there is more transport of potassium than of caseium; when the ratio is i there is no transport of caesium.
Geotaxis in Motile Micro-Organisms
Authors: Roberts A. M. 
Published: April 2021

ABSTRACT
It is suggested that the principal cause of geotaxis in many motile micro-organisms is a gravity-induced hydrodynamic torque, the size of which depends upon the shape of the organism. The nature of the torque has been investigated using small scale models. An expression for the distribution of organisms in long, vertical columns has been derived. The distribution of Paramecium in long, vertical columns has been determined, and it has been shown that the strength of the hydrodynamic interaction is sufficient to account for the negative geotaxis usually exhibited by this organism. The induction of positive geotaxis in certain circumstances has been considered. The survival value of negative geotaxis for free-swimming organisms in search of food may explain the characteristic shape of many protozoa.
Components of A Response Programme Involving Inhibitory and Excitatory Reflexes in the Surf Clam
Authors: Mellon DeForest , Prior David J. 
Published: April 2021

ABSTRACT
Electrical records from ganglion cells in the central nervous system and from intact muscle groups controlling siphon retraction and shell-valve adduction have revealed qualitative similarities in the response characteristics of two neurone-effector systems following stimulation of tactile afferents. Simultaneous electrical records from neurones and muscle indicate that Type I ganglion cells are motoneurones to the fast portion of the posterior adductor muscle. The waveform and polarity of the post-synaptic responses of Type 1 cells depend critically upon the intensity of stimulation over intact sensory pathways. High-intensity input transiently excites the fast portion of the adductor; low-intensity input inhibits the adductor motoneurones. The input organization of Type I neurones therefore permits discrimination of stimulus magnitude and thus controls the characteristics of the response programme."
The Study of Evaporation from Small Surfaces by the Direct Measurement of Water Vapour Pressure Gradients
Authors: Machin John 
Published: April 2021

ABSTRACT
The construction, maintenance and calibration of a sensitive instrument capable of making numerous vapour-pressure measurements within humidity gradients by the dew-point method is described. Coefficients of diffusion of water vapour in air, calculated from observed vapour-pressure gradients and measured rates of evaporation agree with theoretical and other experimental values in still air. Apparent coefficients in wind speeds between 10 and 100 cm/s were significantly lower than those in still air. This finding, together with the performance of the dew-point probe, is discussed in relation to its possible use in the study of evaporation from animals and plants."