bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Physiology of the Antennal Gland of Carcinus Maenas (L.)
Authors: Binns R. 
Published: April 2021

ABSTRACT
The space measured by inulin distribution, the ‘inulin volume’, has been determined, and represents approximately 20% of the body weight in crabs ranging in size from 20·0 to 57·2 g. After the injection of labelled inulin into crabs, the increase in activity of the medium is equal to the fall in blood inulin in all dilutions of sea water. Clearance of inulin from the blood is due only to urine production, and therefore the molecule can be used for quantitative investigations of antennal gland function. Urine production in various concentrations of sea water has been determined by measuring the clearance of inulin from the blood and the rates at which the tracer appeared in the external media. By these methods the mean rate of urine production in 100% sea water was estimated to be 4·4% body weight per day. In dilute sea water the rate of urine production increases ; for example, in 50 % sea water the urine flow is four times greater than in normal sea water.
Innervation Patterns of Fast and Slow Muscle in the Uropods of Crayfish
Authors: Larimer J. L. , Kennedy D. 
Published: April 2021

ABSTRACT
The innervation of 18 uropod and telson muscles in the crayfish has been studied in varying detail. Some muscles display purely phasic properties (short sarcomeres, electrically excitable membrane responses); others are strictly tonic (long sarcomeres, junctional potentials only, spontaneously active motor neurones); a few are mixed, but with anatomical segregation of fibre types. At least 55 efferent neurones are employed to operate these muscles. The tonic muscles all receive peripheral inhibition, and a given inhibitory axon serves only a single tonic muscle. Inhibitory and excitatory axons serving a given muscle discharge reciprocally and often respond to different reflex inputs. The average number of excitatory axons innervating tonic muscles is 2-3. The phasic muscles differ in the richness of excitatory innervation. Some receive as many as five axons per muscle, and as many as four per fibre; others are innervated by only a single motor axon. Many lack inhibitory innervation; where present, peripheral inhibitors may be shared between different phasic muscles. In no case were excitatory axons found to innervate anatomically separate muscles. In ‘mixed’ muscles there is predominantly separate innervation of phasic and tonic fibres; but in at least one case axons were found to serve fibres of both types. The shared axon was phasic in character. Some of the uropod and telson muscles are clearly homologous with axial muscles in more anterior abdominal segments. In a few of the former it was possible to make direct comparisons with the efferent neurones innervating their serial homologues. Differences were found in the size ratios of homologous axons, in their central location, and in their presence or absence.
The Possible Role of the Supra-Oesophageal Ganglion in the Responses of Nephtys (Polychaeta, Annelida) to Changes in Hydrostatic Pressure
Authors: Morgan Elfed 
Published: April 2021

ABSTRACT
The swimming activity of the isolated ‘tail’ region of Nephtys is not affected by changes in hydrostatic pressure. In contrast the responses shown by the isolated anterior third of the body are indistinguishable from those of intact worms. Decerebration, or transection of both circum-oesophageal connectives, also destroys the worms’ ability to respond, whereas transection of the connective on one side only does not. Not one of the sensory structures hitherto described in association with the supra-oesophageal ganglion appears to be the sole mediator of the response.
The Distribution of Po2 and Hydrostatic Pressure Changes Within the Branchial Chambers in Relation to Gill Ventilation of the Shore Crab Carcinus Maenas L
Authors: Hughes G. M. , Knights B. , Scammell C. A. 
Published: April 2021

ABSTRACT
Many studies have been made of the mechanisms which maintain the flow of water across the gills of aquatic animals. In no case, however, has it been possible to formulate a detailed account of the path of the water and blood relative to one another at the exchange surfaces. One of the reasons for this is because the gills are usually contained within enclosed cavities and also they may move during the ventilation cycle. The situation is more complicated as the walls of the branchial cavities may also be involved in the ventilation movements, as, for example, the operculum of teleost fishes. The further detailed analysis of gaseous exchange at gills, which is best known in fishes, has been held up because of the lack of information of this kind. The study of gill ventilation in the Crustacea has distinct advantages from this point of view. The wall of the branchial chamber is rigid and a window can therefore be fixed in it without disrupting the normal hydrodynamic conditions. Furthermore, the rigid exoskeleton allows the animal to be held in a fixed position, and it provides a site for the attachment of recording leads and water-collecting tubing. Another advantage is that the gills of these animals do not move during a normal respiratory cycle. Much work has been carried out on the ventilation of decapod Crustacea but few studies (e.g. Larimer, 1964) have made use of modern pressure recording equipment and oxygen electrodes.
An Acridid Auditory Interneurone
Authors: Rowell C. H. Fraser , McKay J. M. 
Published: April 2021

ABSTRACT
An auditory interneurone (‘alpha neurone’) of Gastrimargus africanus is described. It runs from the mesothoracic ganglion to the brain, and receives summating excitatory inputs from both tympanic nerves. There is no inhibition between the two units or their inputs. The lowest effective frequency is 5−8 kcyc./sec. and response is greatest at the highest frequency tested, 40 kcyc./sec. Threshold at 30 kcyc./sec. is approximately + 50 dB above 0·0002 dynes/cm.2, and response increases with amplitude from 60−90 dB, after which there is no further increase. Increase of amplitude also shortens response latency ; the correlation of latency and response strength is low and very variable. The response is slowly adapting, and mean impulse frequency declines exponentially with increasing length of short sound pulses. Directionality of unilateral sound is signalled by the alpha neurones in only 70% or less of trials, and at least 10% are discriminated ‘wrongly’. The low correlation between response strength and latency improves the signalling of directionality. A second ‘beta’ neurone is described briefly. It signals directionality of a unilateral sound with 100% accuracy, due to mutual inhibition between ipsilateral and contralateral systems, as in some tettigoniid interneurones. Ten or more apparently separate auditory interneurones have now been described in acridids ; this parallels the diversity of receptors described in the ear.
The Physiology of the Antennal Gland of Carcinus Maenas (L.)
Authors: Binns R. 
Published: April 2021

ABSTRACT
It is now well established that the antennal glands of Crustacea, both marine and fresh water, are concerned with regulation of the ionic composition of body fluids (Robertson, 1957; Shaw, 1960; Lockwood, 1962; Potts & Parry, 1964). This activity is considered by some to be the main function of the antennal gland (Webb, 1940; Parry, 1960). Because it produces urine and is undoubtedly concerned with ionic regulation, there is a tendency to discuss antennal gland function in terms of the physiology of the vertebrate kidney. The unqualified inference, often expressed in general zoology texts, that the antennal gland carries out all the functions of the vertebrate kidney is unwarranted, since information concerning antennal gland function, other than ionic regulation, is extremely limited. This is particularly so when considering nitrogen excretion by the antennal gland. A urine-producing ‘excretory organ’ is usually thought of as being concerned with, amongst other things, the elimination of nitrogenous waste products. This function is sometimes ascribed to the antennal gland, despite the fact that there is remarkably little information on this aspect of the physiology of the organ. After a survey of nitrogen excretion by Crustacea and a consideration of analyses of the urine of Maia, Delaunay (1931) concluded that the antennal gland was not concerned with nitrogen excretion and that its importance in this respect has been over-estimated by histo-physiologists. With only a little additional information available, Parry (1960) concluded that the antennal gland was concerned primarily with ionic regulation. Ramsay (1961) was more cautious and considered that because information is so limited, and because little is known of invertebrate biochemistry, the possibility remains that the antennal gland may be concerned with the removal of some excretory products.
Neural Patterns Associated With Ventilatory Movements in Dragonfly Larvae
Authors: Mill P. J. 
Published: April 2021

ABSTRACT
Rhythmic bursts of motor activity associated with the expiratory phase of ventilation have been recorded from the second lateral segmental nerves of posterior abdominal ganglia in Aeshna and Anax larvae. In Aeshna the rhythmic expiratory bursts contain one, or sometimes two, motor units; whereas in Anax there are almost invariably three units. In both animals only one unit is associated with action potentials in the respiratory dorso-ventral muscle. Motor activity synchronized with the expiratory bursts in the second nerves has been recorded from the other lateral nerves and from the last unpaired nerve. In addition the fifth lateral nerves carry inspiratory bursts. It has been confirmed that stimulation of a first segmental nerve can re-set the ventilatory rhythm by initiating an expiratory burst in the second nerves. The original frequency is immediately resumed on cessation of stimulation. The nature of the ventilatory control system in dragonfly larvae is discussed in relation to other rhythmic systems in the arthropods.
Analysis of the Mechanical Responses of Metathoracic Extensor Tibiae Muscles of Free-Walking Locusts
Authors: Usherwood P. N. R. , Runion H. I. 
Published: April 2021

ABSTRACT
Two techniques for indirectly measuring the mechanical responses of metathoracic extensor tibiae muscles (METM’ s) of free-walking locusts are described. First, processed data from neurograms of free-walking (donor) locust preparations were used to stimulate the neurones innervating the METM’s of restrained (recipient) preparations. The mechanical responses of the METM’s of the recipient locusts were recorded isometrically. Second, an electronic model of the METM was designed to give simulated electrical and mechanical responses following activation with processed neurographic data from donor locusts. Both of these techniques give only an indirect estimate of the mechanical responses of the donor METM’s and do not take into account the complex relationships between tension and length in these muscles. The mechanical responses of the METM during a variety of activities, especially walking, kicking and jumping, have been studied using these techniques and further information on the functional role of excitatory and inhibitory motomeurones has been obtained.
Effects of Divalent Cations On Spike Generation in the Longitudinal Somatic Muscle of the Earthworm
Authors: Ito Y. , Kuriyama H. , Tashiro N. 
Published: April 2021

ABSTRACT
Effects of various divalent cations on the spike-generation mechanism in the longitudinal muscle of the earthworm, Pheretima communissima, under sodium-free conditions were observed. In the sodium-free solution the membrane was hyperpolarized from −35 mV. to −55 mV. and the input resistance of the membrane increased from 32 MΩ to 52 MΩ. The spike amplitude was greater in sodium-free solution than in Ringer solution.The amplitude of the spike elicited by intracellular depolarizing currents in sodium-free solution was proportional to the external calcium concentration. The slope of the overshoot potential against tenfold change of the calcium concentration was 26 mV. Similar results could be observed with strontium.The threshold membrane potentials for spike generation varied under various concentrations of calcium. Strontium had nearly the same effect as calcium on the threshold membrane potential.The maximum rates of rise of the spike under various damped membrane potentials were measured in sodium-free solution. The maximum rates of rise of the spike showed sigmoidal curve against the changes of the membrane potential. The half-value of the inactivation curve was estimated to be −32 mV.It was concluded that the spike was elicited by the inward movement of calcium ions, presumably not only in sodium-free solution but also in normal Ringer solution.Strontium and barium ions also carried current during the active state of the membrane.Barium, however, inhibited the potassium conductance of the membrane during the resting and active states, i.e. depolarized the membrane, increased the input resistance of the membrane and prolonged the falling phase of the spike.Magnesium of itself could not elicit the spike in sodium-free solution but prevented spike generation by elevating the threshold membrane potential in the presence of calcium. In the presence of 10 mM Mg, the overshoot potentials recorded in the various concentrations of calcium were not affected, but the maximum rate of rise of the spike was reduced.Cobalt and manganese elevated the threshold membrane potential without changing the resting membrane potential and prevented spike generation. Cobalt was more effective than manganese in preventing spike generations. Cobalt and manganese reduced the amplitude of the overshoot potential and the maximum rate of rise of the spike.
The Direction of the Thrust Produced by the Heterocercal Tails of Two Dissimilar Elasmobranchs: The Port Jackson Shark, Heterodontus Portusjacksoni (Meyer), and the Piked Dogfish, Squalus Megalops (Macleay)
Authors: Simons J. R. 
Published: April 2021

ABSTRACT
It is generally held that the heterocercal tail of elasmobranchs (as well as certain primitive osteichthyans) generates a thrust which is angled upwards. The thrust is thought of as resolved into a horizontal component which drives the animal forward, and a vertical component which aids in the levitation of the creature in the water.
Diagonal Locomotion in De-Afferentated Toads
Authors: Harcombe Elnora Smith , Wyman Robert J. 
Published: April 2021

ABSTRACT
Twenty-eight toads (B. marinus) were de-afferentated by severing all spinal dorsal roots. Every animal made locomotory movements of one kind or another. The normal diagonal pattern was observed fairly often; and, once initiated, this pattern was usually maintained until the animal stopped walking. When a toad made any protraction movement following three steps of the normal pattern, then the fourth step was the appropriate step for the sequence in 66% of cases. When the preceding steps followed the normal pattern, the fifth step was correct in 67% of cases; the sixth in 62%; the seventh in 81% and the eighth in 41%. Random movement predicts 25% in all these cases. It is concluded that spinal afferents are not necessary for the co-ordination of diagonal locomotion.
Body Weight and the Energetics of Temperature Regulation
Authors: McNab Brian K. 
Published: April 2021

ABSTRACT
The interactions of basal rate of metabolism, thermal conductance, body temperature, lower limit of thermoneutrality, and body weight in mammals are compatible with Newton’s law of cooling. A small body weight will normally reduce the level and preciseness of body temperature, but a high basal rate of metabolism or a low thermal conductance may compensate for a small size and permit a high, precise temperature to be maintained. The parameters of energetics that fix the level and preciseness of body temperature in mammals are ultimately correlated in turn with the environmental parameters of climate and food habits. Birds generally have higher temperatures than mammals because the basal rates of metabolism are higher and the conductances lower in birds than in mammals of the same weight.
Extraneuronal Potentials and Potassium Depolarization in Cockroach Giant Axons
Authors: Pichon Y. , Treherne J. E. 
Published: April 2021

ABSTRACT
Elevation of the external potassium concentration resulted in a marked positivation of both intracellularly and extracellularly located micro-electrode tips, in intact connectives, with no appreciable reduction in the amplitude of the recorded action potentials. Sucrose-gap experiments showed that this effect was abolished when tension was applied to the nerve and/or if the connectives were briefly exposed to air. In such preparations continuous and relatively slow potential changes were observed, corresponding to depolarization of the giant axons, with only small extracellular positivations of around 5–6 mV. It is concluded that this effect resulted from the access of potassium ions into the extracellular system most probably as a consequence of the disruption of intercellular occlusions at the inner margin of the perineurium, a situation which contrasts with the restricted intercellular penetration associated with preparations exhibiting extracellular positivation. The possible ionic bases of the latter phenomenon are discussed.
The Viscosity of the Pike’s Endolymph
Authors: Ten Kate J. H. , Kuiper J. W. 
Published: April 2021

ABSTRACT
A micro method, based on Stoke’s law corrected for the influence of adjacent walls, if used for the determination of the absolute viscosity of the pike’s endolymph. Samples of maximally 19 μl were used. The absolute viscosity has an average value of 1·20 ±0·08 cP at 23 °C for ten individual pike labyrinths. The values obtained are compared to those measured by a micro-rolling-sphere viscometer. The absolute values determined by both methods agree within the limits of error. The values obtained for the pike’s endolymph agree with those obtained for other species, if the temperature-dependence of the viscosity of water is taken into account. Though the semicircular canals in mammals are smaller than those in pike of equal body mass, they appear equally sensitive, if the temperature effect on the endolymph viscosity is taken into account.
The Responses of the Marine Amphipods Corophium Arenarium and C. Volutator to Gradients and to Choices of Different Oxygen Concentrations
Authors: Gamble J. C. 
Published: April 2021

ABSTRACT
A gradient or choice apparatus, based on the ‘fluviarium’ principle and suitable for testing the responses of amphipod crustaceans such as Corophium volutator and C. arenarium to different dissolved oxygen concentrations is described. In a gradual oxygen gradient between 6·99 (100% air-saturated) and 0·17 ml O2/l (2·5% air-saturated) C. arenarium shows a significant preference for the oxygenated water while C. volutator is indifferent. The difference between the species is emphasized in experiments with a choice between the above-mentioned oxygen concentrations. Furthermore, in this situation C. volutator shows a greater preference for the deoxygenated water. The response in the choice situation becomes more definite after a period of time. Both Corophium species react immediately at the abrupt oxygen gradient in the choice chamber; C. arenarium is the more sensitive. It is concluded that C. arenarium responds to the dissolved oxygen gradient through an orthokinetic mechanism and that the difference between the two species of Corophium may be correlated with a difference in the oxygen regimes of their respective habitats.
Physiological Basis for Detection of Sound and Vibration in Snakes
Authors: Hartline Peter H. 
Published: April 2021

ABSTRACT
Snakes possess two sensory systems which respond to both air-borne sound and substrate vibration as shown by extracellular slow evoked potentials recorded in the midbrain. One involves the VIII cranial nerve and inner ear (designated ‘auditory system’); the other requires an intact spinal cord and probably originates in skin mechanoreceptors (designated ‘somatic system’). In species of the families Colubridae, Crotalidae, Boidae, the auditory system has a typical U-shaped frequency-threshold curve, similar to those found in other animals, but restricted to a narrow frequency range, c. 150 Hz to 600 Hz. The U-shaped curve has a distinct minimum threshold or best frequency. Frequency-threshold curves for sound and head vibration have only minor differences. The auditory system is not remarkably sensitive to sound. It is about 20 dB less sensitive than the human auditory system for air-borne sound between 200 and 400 Hz. It is remarkably sensitive to head vibration: at the best frequency, 1 Å peak-to-peak amplitude is suprathreshold. The auditory system responds not only to stimuli at the head but to sound and vibration delivered to the body alone. Responses to body stimulation by sound are caused by the same sensory end-organ that responds to head vibration. The role of the body in picking up sound for the auditory system can be substantial; thus the lung plays an important part in snake hearing, a novel situation among land vertebrates. The somatic system is not as sensitive to sound or to vibration as is the auditory system over most of the latter’s frequency range. The somatic system has a relatively flat frequency-threshold curve which lacks a distinct best frequency. The frequency range extends both above and below the range of the auditory system, 50−1000 Hz. The somatic system is insensitive to vibration of the head. Evoked slow potentials fail to show that either spinal or auditory system distinguishes between vibratory energy from the air and from the substrate. It is proposed that intensity information from the auditory system could be compared by the snake’s brain with intensity information from the snake’s somatic system in order to determine the relative amounts of air-borne sound and substrate vibration in an unknown natural stimulus.
The Efference Copy Neurone
Authors: Johnstone J. R. , Mark R. F. 
Published: April 2021

ABSTRACT
Neurones which fire at the same time as saccades are found in the tectal commissure of carp. They are unaffected by visual stimuli or by paralysis of eye muscles and so their activity is not directly related to sensory input. Twenty-two units have been examined. They fire in bursts only during eye movements and only for a particular direction of movement, either eyes-left or eyes-right. They begin to fire a few milliseconds before eye movement begins, slowly at first, reach a maximum frequency of about 300 Hz, then slow again and stop after about 100 ms. In two instances such units have been recorded simultaneously in paralysed fish with a tonically firing unit, presumably visual, which was suppressed during each burst. In one case the tonic activity after each burst was increased, in the other it was decreased. We suggest they are efference copy neurones, responsible for perceptual stability during eye movements. Their possible function is discussed in detail. They are not tectal motoneurones because the same eye movements continue after total removal of the tectum. Neither are they dependent on sensory input resulting from eye movement because their discharge patterns are unaffected by darkness or paralysis.
Dependence of Flight On Temperature Regulation in the Moth, Manduca Sexta
Authors: McCrea M. J. , Heath J. E. 
Published: April 2021

ABSTRACT
Manduca sexta can behaviourally regulate its temperature, but the temperature level is not determined by a simple thermal set-point. Thermoregulation is not localized in a cephalic nervous centre. Both of these characteristics distinguish thermoregulation in M. sexta from thermoregulation as seen in vertebrates. Sustained high temperature is a requisite for flight activity, but regulation of internal temperature is a secondary feature in M. sexta subserving efficient tuning of the flight system.