bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Physiology of the Vertebrate Autonomic Nervous System. I. Innervation of the Urinary Bladder of the Toad (Bufo Marinus)
Authors: Burnstock G. , O’shea Judith , Wood Margaret 
Published: April 2021

ABSTRACTThe anatomy, physiology and pharmacology of the innervation of the bladder of the toad (Bufo marinus) have been studied. Motor fibres only have been demonstrated to innervate the toad bladder. These fibres travel mainly in the 9th spinal nerve, but may also be present in the 10th, 7th and occasionally in the 8th spinal nerves. Usually, all these fibres reach the bladder via the pelvic nerves. The response of the bladder to nerve stimulation was qualitatively the same whichever nerve was stimulated and whatever parameters of stimulating pulse were applied. The optimal frequency at 20° C. was about 20 pulses/sec. ACh causes contraction of the toad bladder. Adrenaline and noradrenaline usually cause relaxation, but dopamine and low concentrations of noradrenaline can cause weak excitation. The bladder is insensitive to both histamine and 5-HT. Atropine reduced the response of the bladder to pelvic nerve stimulation by up to 50%. Eserine did not potentiate the nerve-mediated response, but nor did it potentiate the direct action of ACh. All the adrenergic blocking agents used reduced or completely blocked the nerve-mediated response, but the response to applied ACh is also reduced under these conditions. All the ganglionic blocking agents tested reduced the nerve-mediated response. However, only mecamylamine markedly reduced the response without affecting the action of applied ACh. It was concluded that a division into sympathetic and parasympathetic innervation of the toad bladder was not justified, and that the nerve fibres which innervate this organ are probably all of one type, regardless of their origin, with at least 50 % of the pelvic nerve fibres being pre-ganglionic. The pharmacological evidence presented favours the view that these nerves are cholinergic rather than adrenergic. The evolutionary implications of these results have been discussed.
The Relation of Oxygen Consumption to Substrate Particle Size in Two Burrowing Mayflies
Authors: Eriksen Clyde H. 
Published: April 2021

ABSTRACT
This study is concerned with the relation of oxygen consumption to substrate particle size in the morphologically similar burrowing mayflies Ephemera simulans and Hexagenia limbata. Nymphs, 16 –24 mm in length, were placed at 13·0 ° C. for 24 hr. before experimentation. Oxygen consumption experiments employed the standard ‘oxygen consumed in a closed bottle’ technique and a modification. The standard technique was referred to as the ‘blank-bottle’ method, while the modification was called the ‘substrate-bottle’ method (washed substrate fractions were placed in the bottle). The relationship between substrate particle size and oxygen consumption was indicated by a bimodal curve. The oxygen consumption fell, rose and fell once more as the particle size decreased from ϕ – 4 to ϕ + 5. Substrate selection experiments with E. simulans nymphs revealed an inverse relationship between selection for particle size and oxygen consumption. The burrowing front legs of the nymphs seem to be modified for a given substrate (coarse for E. simulans ; fine for H. limbata) and, the less favourable the substrate, the more work that must be done to gain admittance or to burrow further. The particle size in which the nymphs showed the least oxygen consumption was considered to be an ‘optimal substrate’ (ϕ – 1 for E. simulans and probably silt for H. limbata).
Properties of Interneurones in the Abdominal Nerve Cord of A Dragonfly Nymph
Authors: Fielden Ann 
Published: April 2021

ABSTRACT
Responses of single interneurones in the abdominal connectives of the dragonfly nymph following electrical stimulation of the segmental nerves were investigated. Excitation and inhibition were seen in fibres with a resting discharge. Repetitive trains of impulses, varying between units and with the source of the afferent volley, were common. Changes in the intensity and frequency of stimulation affected the pattern of the repetitive responses. An increase in the intensity of the volley shortened the latency and increased the length of the train, while an increase in rate reduced the number of impulses. Most interneurones responded to stimulation of more than one afferent pathway. Multisegmental fibres and multiple connexions of fibres were common. These responses are compared with those of spinal interneurones and discussed in relation to their function in the animal.
Analysis of the Haemolymph of Arion Ater L. (Gastropoda: Pulmonata)
Authors: Roach D. K. 
Published: April 2021

ABSTRACT
Methods are described for the collection of slug haemolymph and its analysis for cations, anions, total electrolytes, protein, Δ and pH. Of the cations measured, potassium and calcium show the greatest variation, being two to three times as variable as sodium, the most constant. About 20 % of the blood calcium exists in a bound form. Of the anions measured, chloride is the most concentrated and least variable. Sulphate and alkalinity are about equally variable, three times the chloride fluctuation. The phosphate concentration is very low. The variation of total electrolytes is only half that of the total solutes, as measured by Δ, while protein is very variable. The pH is remarkably alkaline but varies only within narrow limits. Formulae are given for two physiological salines, capable of maintaining both muscular and ciliary activity.
The Control of Meal Size in the Blood Sucking Bug,Rhodnius Prolixus
Authors: Bennet-Clark H. C. 
Published: April 2021

ABSTRACTThe object of this investigation was to examine the mode of operation of the pharyngeal pump of Rhodnius and its possible role in determining rate of feeding and maximum size of meal. The rate of pulsation of the pump remains constant throughout the meal, falling only in the last few seconds. The pump is filled by muscular withdrawal of the piston and empties by elastic return of the piston. The properties of the pump, which is very small, were studied on a working model. The model displayed marked ‘click’ properties, the force behind the emptying stroke increasing as the stroke progressed ; thus the emptying stroke, once initiated, was always completed. The pressure volume relations of the isolated abdomen were explored as a function of time. It is concluded that the pump is stopped at a critical abdominal pressure of 2·5 cm. Hg., which prevents the initiation of the emptying stroke, that the rate of feeding is mainly limited by the rate of filling of the pump and that the size of the meal taken depends upon the ease with which the cuticle can be stretched. Confirmatory evidence is adduced and discussed.
Studies On Crop Function in the Cockroach (Periplaneta AmericanaL.)
Authors: Davey K. G. , Treherne J. E. 
Published: April 2021

ABSTRACTThe nervous pathway involved in the control of crop-emptying has been worked out by the method of nerve section. This pathway involves nerve 5 from the pharynx to the frontal ganglion, the recurrent nerve, the oesophageal nerve and ganglion, the ingluvial nerve and ganglion Function is not abolished by nerve section between the brain and the frontal ganglion. The sensory end of the pathway is in the pharynx where there is a sense organ which, it is suggested, is an osmoreceptor. A preliminary account of its structure is given.
Spectral Sensitivity of the Herring, Clupea Harengus L
Authors: Blaxter J. H. S. 
Published: April 2021

ABSTRACT
Herring (Clupea harengus) require light for feeding and avoiding nets. The threshold light intensity for these behaviour patterns and also for phototaxis, using different colours of tight, was measured and used to obtain spectral sensitivity curves. The maximum sensitivity of dark-adapted herring lay between 510 and 520 mμ. The threshold light intensity, using white light, varied from 3·6 × 10−2 to 2·9 × 10−4 photopic lux, depending on the behaviour being studied. A parallel experiment on a dark-adapted human subject gave a maximum sensitivity at 500 mμ and a threshold light intensity, using white tight, of 3·4 ×10−7 photopic lux. Pigment extracted from dark-adapted eyes of herring had a maximum absorption at 500 mμ. Suggestions are made for measurement of underwater light intensity in studies on fish behaviour.
The Passage of Spermatozoa Through and Into the Zona Pellucida of the Rabbit Egg
Authors: Dickmann Z. 
Published: April 2021

ABSTRACT
To obtain information about the sperm pathway through the zona pellucida of the rabbit egg, ordinary and phase contrast microscopy were used to study (1) zonae through which spermatozoa had passed, and (2) spermatozoa within zonae.
The observations revealed that the spermatozoon makes a narrow slit in the zona as it passes through it. Such slits have a characteristic shape—’ the penetration curve ‘. It is concluded that to pass through the zona, the spermatozoon must follow the penetration curve.
Most of the spermatozoa observed within the thickness of the zona apparently started on the curved course and then stopped. They may have stopped within the zona because they were deficient in a substance which normally acts in conditioning the zona to allow spermatozoa to pass through it.
Hair-like structures protrude from the front ends of sperm heads into the zona. No definite conclusion has been reached as to whether they are slits in the zona or solid structures ; however, the pictorial evidence favours the interpretation that they are filaments protruding from the sperm heads.
Relative Refractoriness and Patterned Discharge of Locust Flight Motor Neurons
Authors: Wilson Donald M. 
Published: April 2021

ABSTRACT
The threshold recovery after impulse propagation in locust peripheral motor axons to flight muscles is described. The refractoriness is large enough to have functional significance for at least 10 msec, and may be detected after 50-100 msec. The refractoriness to successive impulses accumulates. Ganglionic and axonal preparations demonstrate frequency division, apparently due to the refractoriness of the motor neuron. Accumulating refractoriness gives rise to non-integral division. Behaviour of the locust preparations is compared to that of an electronic model. Antidromic stimulation during flight shows that refractory oscillation may regulate the interval between the closer spaced pairs of impulses in the motor units during flight, but that the wingbeat cycle must have another cause.
Frog Fast Muscle: I. Mechanical Power Output in Isotonic Twitches
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
The paper is primarily concerned with predicting the response of the muscle (frog ilio-fibularis fast fibres) to a given stimulus under given conditions of load. The predictive value of theories based on ‘active state ‘is considered in this context. A method is described for measuring the speed of shortening at frequent intervals during an isotonic twitch. A family of speed vs. tension curves is drawn up, each curve representing a particular time after the stimulus. These are translated into power vs. tension curves. The rate of fall of mechanical power output increases linearly with time after the stimulus, but is independent of tension. At the beginning of the twitch, mechanical power output increases slightly with temperature, but later in the twitch the trend is reversed, as rate of fall of power also increases with temperature. The high extensibility, characteristic of resting muscle, reappears suddenly at the end of an isotonic twitch, causing a ‘break’ in the speed record. This occurs earlier at low than at high tensions. The basis of predicting an isometric twitch from isotonic data, based on certain assumptions which have been made by previous authors, is explained. The tension peak in an isometric twitch is reached sooner than would be predicted on these assumptions.
Functional Design of the Tracheal System of Flying Insects as Compared with the Avian Lung
Authors: Weis-Fogh Torkel 
Published: April 2021

ABSTRACT
A process as demanding in power as that of flapping flight influences most physiological systems very greatly and above all the respiratory system. In the thorax of adult winged insects, it has become so intricate and integrated by fusion and extension that it is difficult to describe in comparative or in functional terms. In fact, because of lack of knowledge about the functional morphology little is known about the supply of oxygen to the wing muscles and the exchange of respiratory gases between the thorax and the ambient air.
Response of Fast Muscle Fibres to Series of Impulses
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
The peak power at the beginning of an isotonic twitch is increased if it is initiated while a previous twitch is still in progress ; the effect is cumulative over the first few twitches of a series. The time taken to drop from peak power to zero power is not affected. The power cycle in an isometric tetanus is considered and a possible method of predicting isometric tension, as a function of stimulus rate, from isotonic measurements, is explained. The steady component of tension is found to vary approximately with the logarithm of the stimulus rate in various fast muscles of the frog and dogfish. The problem of incorporating the results of the present and previous papers in an empirical muscle model is reconsidered.
Gill Ventilation and the Role of Reversed Respiratory Currents in Carcinus Maenas (L.)
Authors: Arudpragasam K. D. , Naylor E. 
Published: April 2021

ABSTRACT
A method is described for obtaining continuous records of the direction of flow of the respiratory current of Carcinus by recording changes of pressure in the gill chamber. Frequent and rhythmic reversals of the normally forward-flowing respiratory current appear to irrigate the upper surfaces of the posterior gills and do not serve primarily to clean the gills. The rate of reversal of this respiratory current increases spontaneously at times of high tide. It decreases under conditions of carbon-dioxide accumulation and increases under conditions of oxygen depletion in the absence of excess carbon dioxide. The pattern of gill ventilation varies according to whether crabs are totally in water, partially buried in sand, or in very shallow water.
Factors Altering Spiracle Control in Adult Dragonflies: Water Balance
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
Dragonflies caught in the wild display a marked variation in the degree of control exercised over their spiracles. In the laboratory desiccation produces tighter control and hydration looser control of spiracle 2: that is, in a partially desiccated insect the thresholds of the spiracular responses to carbon dioxide and to oxygen lack are raised. In desiccated insects the frequency of motor impulses to the spiracles is higher than in hydrated individuals. These effects can be reproduced by perfusion with physiological salines of various strengths. The reaction does not depend on the osmotic pressure of the solution but on the concentration of one or more of its constituents. The isolated mesothoracic ganglion is able to mediate this reaction.
Factors Altering Spiracle Control in Adult Dragonflies: Hypoxia and Temperature
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
The steady output of impulses in the two motor axons to spiracle 2 of mature individuals of the large African gomphid dragonfly, Ictinogomphus ferox Rambur, is reduced in frequency with hypoxia and abolished in about 2 % oxygen. After perfusion of the insect with hypertonic saline the threshold of this response is raised, whereas, following perfusion with hypotonic solutions, it is lowered. Teneral dragonflies give only a weak response to hypoxia—comparable to that of the mature insect perfused with hypertonic saline. This may help to conserve water before feeding commences. Little change in the frequency of motor impulses follows gassing with carbon dioxide mixtures in air up to 20% ; this is in contrast to the reactions reported in some other insects. A raised temperature causes an increased frequency and the Q10 for the reaction is 2·7 (15-25° C.). Above 30-35° C. the frequency declines rapidly. A rise in the threshold of the hypoxic response does not accompany the increased frequency brought about by a raised temperature. A similai; increase in frequency occurs when either the head or the thorax alone is heated. Pterothoracic temperatures of about 30-35° C. are probably maintained in this species while perching in the sun. In this temperature range it is able to take off instantly when potential prey is sighted. High pterothoracic temperatures are considered in relation to spiracle control.
‘Sliffer’s Patches’ and the Thermal Sense in Acrididae (Orthoptera)
Authors: Makings P. 
Published: April 2021

ABSTRACT
The term ‘Slifer’s patches’ is applied in this paper to the series of specialized areas of cuticle which Slifer named ‘antennal crescents’ and ‘fenestrae’. None of the existing evidence supports her suggestion that these patches have a thermoreceptive function. Behaviour changes caused by damaging them can be reproduced by damaging other parts of the cuticle. The antennal-lowering response is not dependent upon stimulation of the patch situated near the antennal base. Destruction of all of the patches does not reduce the ability of locusts to orientate to, and assume the basking posture under the influence of, a lamp ; nor does it reduce their ability to respond similarly to a heat source in darkness and with a cooled floor on which the locusts move. It does not change the leaning response produced by heat stimulation of decapitated locusts. The antennal scape and articular membrane are more effective in producing an antennal-lowering response when stimulated by a hot probe than are the antennal patches or adjacent areas. The median response-time for kicking of the hind legs in response to the local application of a hot probe to the abdomen is shorter when the probe is applied to a part of the normal cuticle than when it is applied to a patch. The antenna, including the flagellum, is sensitive to heat. Stimulation of the distal part of the flagellum by means of a hot wire produced an avoiding response when the wire temperature rose above 40°C. If one antenna is removed locusts in arena tests show a marked tendency to turn the intact side of the body away from a lamp, or a heat source in darkness. Locusts with both antennae removed show a reduced tendency to akinesis under the influence of a heat source in darkness. The detection by locusts of heat stimulation at intensities above the nociceptive threshold may depend on a sensory system which is at least partly distinct from that involved at lower intensities.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D. 
Published: April 2021

ABSTRACT
Observations of earlier workers on the chromatic responses to local heating or cooling of the skin of Phoxinus have been confirmed. They have also been found to hold true for anaesthetized fish, in which finer control and observation are possible. The results of a series of nerve-section experiments are held to exclude any possibility that the responses of the intact fish are mediated by a nervous reflex from thermoreceptors in the skin. The responses of melanophores following section of the chromatic motor tracts, or when isolated from the body, are considered to be independent cellular responses. Normal responses in the intact fish show clear temperature thresholds and are completely dependent upon continuation of the respiratory rhythm. Possible physiological mechanisms for mediating these non-adaptive responses are discussed and a new hypothesis is put forward.
Central Control of an Insect Segmental Reflex: I. Inhibition by Different Parts of the Central Nervous System
Authors: Fraser Rowell C. H. 
Published: April 2021

ABSTRACT
An earlier paper (Rowell, 1961a) described a reflex cleaning or grooming movement by the front leg in Schistocerca gregaria; it is evoked by stimulation of the sensilla of the prothoracic sternum. In the unrestrained animal this response can only rarely be seen, but under experimental conditions it can be obtained reliably if the connectives uniting the prothoracic ganglion to the rest of the C.N.S. are cut, provided that the tarsi of the front legs are not allowed to contact anything. Under all other conditions the reflex is partially or completely inhibited.
Co-Ordinating Systems and Behaviour in Hydra
Authors: Passano L. M. , Mccullough C. B. 
Published: April 2021

ABSTRACT
A technique of recording electrical activity from an intact, essentially normal specimen of Hydra is described. The existence of regularly recurring co-ordinated longitudinal contractions of the ectodermal muscles is confirmed and re-emphasized. Such contractions are found to consist of a patterned series of individual co-ordinated contractions, each preceded by a single large, compound potential. The overall contraction, consisting of a variable number between 5 and 12 or more contractions depending on species, is thus called a contraction burst. These contraction-burst potentials originate endogenously ; they are considered to be the most important effector activity in Hydra. Contraction-burst potentials originate in the hypostome and are conducted throughout the column at approximately 15 cm./sec. Contraction-burst patterns have been studied quantitatively in two species, showing interspecific differences between both regular contraction bursts and those associated with locomotion. Certain extrinsic and intrinsic variables affect contraction-burst frequency. Day-light, and nutritional state, both modify this rate, with the former giving rise to a circadian activity cycle under natural conditions. Single electric shocks usually cause a single co-ordinated muscle contraction. Such stimuli can markedly reduce endogenous contraction-burst activity. Sudden illumination interrupts contraction bursts temporarily, even halting those in progress. Blue light is most effective. This stimulus has been used as a tool to investigate the properties of the pacemaker systems concerned with contraction bursts. The nature and properties of these pacemakers is discussed.
Electrophysiological Investigations of the Heart of Squilla Mantis
Authors: Brown Hilary F. 
Published: April 2021

ABSTRACT
There was a seasonal variation in the strength of the effect which extracts of the pericardial organs of Squilla mantis exert on the animal’s heart. The extract was most effective in the spring and summer. An investigation was made of the way in which the pericardial organ extract acts at a cellular level to increase the amplitude and frequency of the heart beat. The extract did not affect the rate of impulse firing within the ganglionic nerve trunk burst. It increased the ratio of the number of impulses per burst : burst interval. It initiated burst firing in complete g.n.t.’s which had become quiescent, and in those which had previously given only one impulse in response to an applied stimulus. The junction potentials recorded intracellularly from Squilla heart muscle increased in height on adding pericardial extract. Some of this increase resulted from facilitation of the junction potentials at the increased heart rate, but 10–20% of the increase was rate-independent. These results suggest that the extract acts at a minimum of two primary sites within the heart.