bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormonal Control of Excretion in the American Cockroach
Authors: Mills Richard R. 
Published: April 2021

ABSTRACT
When adult male cockroaches are deprived of water for 3 days the subsequent overcompensation of water ingestion causes the release of a diuretic hormone into the blood. Ligation experiments indicate that the hormone was released from the posterior part of the abdomen. The testing of various tissues extirpated from within this region revealed that only extracts of the terminal abdominal ganglion could promote diuresis. Homogenates of ganglia from normal animals fail to elicit the diuretic response ; this and other evidence suggests the presence of an antidiuretic hormone.
Conduction Velocities and Their Temperature Coefficients in Sensory Nerve Fibres of Cockroach Legs*
Authors: Chapman K. M. , Pankhurst J. H. 
Published: April 2021

ABSTRACT
The cockroach-leg preparation of Pumphrey (1936) and Pringle & Wilson (1952) lends itself easily to measurements of conduction velocity in afferent nerve fibres from many of the larger mechanoreceptive sensilla of the leg. Conduction velocity is a quantity that can be measured quite precisely, and it has an important bearing on several open problems involving sensory mechanisms in insects, as well as in cellular neurophysiology more generally. One group of problems relates to the sensory transfer functions for tactile spine mechanoreceptors of Periplaneta, determined by Pringle & Wilson (1952) and Chapman & Smith (1963). Sensory transfer functions are quantitative expressions of the stimulus-response relationship, which describe some aspects of the temporal sensory code used in information transmission, and which provide useful insight in identifying component transducer mechanisms in the sensory ending. Conduction velocity is important in this context because it contributes quantitatively to the sensory code, and because it generates a quantifiable experimental artifact in the analysis of transducer mechanisms. In the present work these effects are evaluated and are shown to be small but not negligible.
Hepatic Vein Sphincters in Elasmobranchs and Their Significance in Controlling hepatic Blood flow*
Authors: Johansen Kjell , Hanson David 
Published: April 2021

ABSTRACT
The liver exerts its influence in general cellular metabolism and homeostatic control within limits set by the quality and quantity of blood perfusing it. Hepatic outflow reflects hepatic portal flow which is influenced by the diverse blood flow requirements of other visceral organs engaged in metabolic and absorptive functions. In addition, the hepatic blood flow constitutes a sizeable fraction of the total venous return to the heart and is important in the maintenance of an effective overall circulation.
The Strength of the Pigeon’s Wing Bones in Relation to Their Function
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
Simple methods are described for applying known bending and twisting moments to pigeon bones. The ultimate bending and torsional strengths of the humerus and radio-ulna are determined. Lift distributions are calculated from a strip diagram on the assumption that local lift coefficient is constant across the span. The position of the centre of lift is calculated for (a) gliding, in which the relative air speed is entirely due to the forward motion of the bird; and (b) hovering, in which it is entirely due to rotation of the wing about the shoulder joint. Estimates of the ultimate load factor of the humerus in bending and twisting yielded 8·8 and 9·0 respectively in gliding, and 5·7 and 5·6 in hovering. Corresponding figures for the radio-ulna were 6·9 and 9·1 in gliding, and 4·0 and 5·1 in hovering. The pectoralis insertion is strong enough to apply 4·2g f in gliding and 2·9g in hovering, so the muscles would be forcibly extended before any danger could arise of the bones being broken by excessive lift. A lift coefficient of at least 3·4 is achieved during the downstroke of hovering.
Command Interneurons in the Crayfish Central Nervous System*
Authors: Atwood H. L. , Wiersma C. A. G. 
Published: April 2021

ABSTRACT
The motor effects evoked by stimulation of each of eight command fibres in the circumoesophageal commissures of the crayfish are described. The fibres obtained appeared to have widespread connexions in all or most of the lower ganglia. For certain fibres the response was stronger on the homolateral side of the animal ; for others it was symmetrical. The frequency of stimulation of a command fibre generally had a pronounced influence on the speed of the evoked response. In addition, segments of the total response could be elicited selectively by alteration of the frequency and duration of stimulation. Although the responses associated with most of the fibres were not sensitive to the fine temporal pattern of the applied stimulation, for one fibre the motor output depended clearly on the spacing of the stimulating pulses.
The Initiation of Action Potentials in the Somatic Musculature of Ascaris Lumbricoides
Authors: Castillo J. del , de Mello W. C. , Morales T. 
Published: April 2021

ABSTRACT
The results of previous work (DeBell, del Castillo & Sanchez, 1963; del Castillo, de Mello & Morales, 1963) led to the conclusion that the rhythmic action potentials controlling the somatic muscle layer of Ascaris are of myogenic origin, being generated at the muscle syncytium. As shown in Fig. 1, this is a strip of tissue formed by the interlacement of the terminal arborizations of the arms (or innervation processes) that each individual muscle cell sends to either the dorsal or the ventral main nerve cords.
Zinc Regulation in the Freshwater Crayfish (Including Some Comparative Copper Analyses)
Authors: Bryan G. W. 
Published: April 2021

ABSTRACT
In the Plymouth area, estuarine decapod crustaceans like Carcinus maenas and Palaemon serratus have much higher concentrations of zinc in the blood than marine species such as Homarus vulgaris and Maia squinado. These differences between species with different powers of osmotic and ionic regulation have not been explained, but they were the starting-point of the present work. This is a study of the freshwater crayfish Austropotamobius pallipes pallipes (Lereboullet) to see whether adaptations to fresh water include modifications in zinc regulation.
The Derivation of the Motor Command to the Spiracles of the Locust
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
Three principal motor patterns have been distinguished in the nerves to the closer muscle of spiracle 1 of the locust. Pattern 1 brings about muscular contraction and spiracle closing; pattern 2 maintains the closure and may be brought about either by the activity of pacemakers located in each motoneurone or by synaptic activity or by a mixture of both. The possible origins of pattern 2 activity have been located by antidromic stimulation and by observations on the occurrence of impulse synchronization between the units of one segment and those of adjacent segments. In pattern 3, firing slows or stops and the spiracle opens. In most individuals of Locusta, pacemaker activity predominates in pattern 2 firing, while in Schistocerca synaptic activity is more common. Different individuals of either species may remain consistent to one firing plan for long periods ; their effect at normal frequencies at the muscle is indistinguishable. Electrical stimulation of split bundles of the connectives has gone some way to distinguishing between the activity of possibly three command interneurones which run from the metathoracic ganglion and synapse with the spiracle motoneurones. These produce 1:1 excitation, acceleration of pacemaker activity or inhibition of the pacemakers, and in the intact insect are believed to bring about accurate synchronization of the spiracle movements with abdominal pumping.
The Function of the Conus Arteriosus in the Port Jackson Shark, Heterodontus Portusjacksoni
Authors: Satchell G. H. , Jones M. P. 
Published: April 2021

ABSTRACT
The conus arteriosus is a muscular chamber interposed between the ventricle and ventral aorta in Elasmobranchii, Holocephalii and the more primitive families of bony fish. Since Duverney (1702) suggested that it functioned as an extra ventricle, it has been variously regarded as an elastic reservoir to minimize pressure fluctuations (Keith, 1924; Daniel, 1934), an accessory pumping chamber (Gegenbaur, 1866, Stöhr, 1876, Sudak, 1965), and a valvular structure to regulate the out-flow of blood from the ventricle (Home, 1823; Pettigrew, 1864; March, Ross & Lower, 1962). Both the conal pressure recordings of Sudak (1965) in Mustelus canis and the cinematographic analysis of March et al. (1962) in Triakis semifasciatus show that conus systole occurs prior to ventricular relaxation. However, our knowledge of the sequence of the valve movements is still largely conjectural. This paper reports an investigation of conal function in the Port Jackson shark, Heterodontus portusjacksoni. The anatomy of the conus will be briefly described, and a hypothesis of its mode of action will be out-lined. The evidence for this will then be presented, and the function of the conus discussed.
Membrane Potentials in the Central Nervous System of a Phytophagous Insect (Carausius Morosus)
Authors: Treherne J. E. , Maddrell S. H. P. 
Published: April 2021

ABSTRACT
The nerve cord of the stick insect is surrounded by a fat-body sheath. This sheath encloses an extraneural space and thus interposes an additional fluid compartment between the neural lamella and the haemolymph. The axons in the thoracic connectives were found to be relatively small, the largest ones averaging 7−11 μ in diameter. The apparent resting potentials of axons, impaled with glass capillary microelectrodes, were found to be relatively small, averaging only 25·1 mV., with an overshoot of 59·3 mV. in action potentials in intact preparations. In the absence of the neural fat-body sheath the resting potentials were increased to a mean value of 40·3 mV., there being no significant alteration in the total amplitude of the action potentials. This effect appears to result from the interpolation of a positive potential of some 15−20 mV. between the indifferent and recording electrodes. The positive potential was abolished, in intact preparations, when the nerve cords were bathed with solutions of elevated chloride concentration. Positive potentials were also obtained when gradients of chloride ions were maintained across the isolated fat-body sheath. It is suggested that the positive potentials may result from a chloride diffusion potential across the neural fat-body sheath. The results are discussed in relation to the ability of the axons of this species to function in ganglia and connectives bathed with solutions of low sodium concentration.
Some Effects of Receptor Muscle Contraction on the Responses of Slowly Adapting Abdominal Stretch Receptors of the Crayfish
Authors: Brown M. C. 
Published: April 2021

ABSTRACT
Stimulation of the motor fibres innervating the slowly adapting abdominal stretch receptors of the crayfish was carried out under the following circumstances : With the receptors at a constant length the frequency of stimulation was varied. A maximal response from the receptors, which averaged about 50 impulses/sec., was obtained with stimulation rates of 50 − 80/sec. But low rates of stimulation (e.g. 10/sec.) had a powerful excitatory action, often 70% of maximal. With the receptors stretched different amounts the motor fibres were stimulated at a constant rate. The increase in the receptor discharge caused by the contraction was the same over the range of lengths studied. The receptors were stretched at a series of constant velocities (0· 05 − 10 mm./sec.) to the same final length with and without motor-nerve stimulation. The contraction increased the frequency rise during the dynamic phase of stretch and increased the amount by which the frequency decayed at the end of the ramp. The phasic response of the de-efferented receptor has previously been described by the following transfer function Fs = a Г (1 — k)sk, where a and k are constants. To a first approximation the effect of receptor contraction on this phasic response was to increase the value of the constant a, but to leave k unaffected.
Ionic Regulation in the Queen Conch, Strombus Gigas (Gastropoda, Prosobranchia)*
Authors: Little Colin 
Published: April 2021

ABSTRACT
The concentrations of sodium, potassium, calcium, magnesium, bicarbonate, chloride and sulphate in the haemolymph of Strombus have been measured. Greatest differences between concentrations in haemolymph and sea water were found for bicarbonate and sulphate. Haemolymph has been compared with haemolymph dialysed against sea water, and the comparison suggests that sodium, calcium, magnesium and chloride are in passive equilibrium; potassium is actively absorbed, and sulphate is actively eliminated. Nernst potentials have been calculated for the measured concentration ratios of ions in haemolymph and sea water, and have been compared with the potential difference measured between haemolymph and sea water in vivo. These observations show that sodium and magnesium are in passive equilibrium; chloride is taken up actively (significant at the 5 % level of probability) and potassium may be taken up actively (significant at the 10% level); calcium and sulphate are actively eliminated (significant at the 5% level). The differences between these conclusions and those derived from dialysis experiments are discussed. Analyses have been made of the composition of pericardial and kidney fluid, and the rate of loss of urine has been measured. It is concluded that pericardial fluid is produced by ultrafiltration from the haemolymph; the mean rate of production of urine is low, at 11·5 % of the blood volume per day (3 ml./kg./hr.), but small differences of concentration between haemolymph and sea water indicate that calcium and potassium must be lost at a relatively faster rate than other ions. Analyses have been made of the composition of stomach fluid. This contains almost no sulphate or bicarbonate, but the concentrations of other ions are similar to those of haemolymph, except for calcium, which is probably derived from calcareous sand grains. The basic mechanism of formation of stomach fluid has not been explained. The rate of loss of stomach fluid to the exterior is very slow (0·10−0·16 ml./ kg./hr.), but this fluid is rinsed out of the rectum by sea water drawn in from the outside. An analysis of one sample of mucus from the mantle cavity suggests that mucus glands may be responsible for the low concentration of sulphate in the haemolymph.
Sodium Regulation in the Fresh-Water Amphipod, Gammarus Pulex (L.)
Authors: Sutcliffe D. W. 
Published: April 2021

ABSTRACT
Sodium influx and loss rates in Gammarus pulex were measured at constant temperatures. The sodium loss rate was immediately influenced by a change in temperature, with a Q10 of 1·5 to 2·0 at temperatures between 0·3 and 21·5°C. The sodium influx rate is apparently influenced in the same way. The sodium uptake mechanism in G. pulex from three localities was half-saturated at an external concentration of 0·10−0·15 mM/1. sodium. The total sodium loss rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to about 0·2 mM/1. sodium. 18 % of the sodium was lost in urine with a sodium concentration estimated at 30−50 mM/1. The remainder of the sodium loss was due to diffusion across the body surface. In animals acclimatized to concentrations below about 0·2 mM/1. sodium the sodium loss rate was reduced, due to (a) a lower diffusion rate following a fall in the blood sodium concentration, and (b) the elaboration of a more dilute urine. There was a very close association between changes in the blood sodium concentration, the elaboration of a very dilute urine, and the rate of sodium uptake at the body surface. The results indicate that a fall in the blood sodium concentration leads to simultaneous activation of the sodium uptake mechanisms at the body surface and in the antennary glands. It is estimated that, by producing a dilute urine, total sodium uptake in G. pulex is shared equally between the renal uptake mechanism and the mechanism situated at the body surface. In sea-water media G. pulex drinks and expels fluid from the gut. In a medium slightly hyperosmotic to the normal blood concentration the amount imbibed was equal to the normal rate of urine flow when in fresh water.
The Ability of Limulus to See Visual Patterns*
Authors: Von Campenhausen Christoph 
Published: April 2021

ABSTRACT
Phototactic reactions of young and adult Limulus are described. A method has been developed for studying the optokinetic responses of young animals to moving patterns. Evidence is presented that young animals can see the movement of patterns which consist of light and dark vertical stripes. The response is weak, and visual stimuli appear to have little influence on the behaviour of Limulus. Reasons for this are discussed.
Response Heterogeneity in Adductor Muscle Efferents of the Surf Clam*
Authors: Mellon DeForest , Mpitsos George J. 
Published: April 2021

ABSTRACT
Neuromuscular control in the Mollusca presents numerous interesting problems to the comparative physiologist. Among these are the extent of polyneural and multi-terminal innervation, the possibility of peripheral inhibition, and the anatomical basis for wholly peripheral reflex activities. Perhaps in no area are the problems more intriguing—and the experimental results more equivocal—than with regard to the physiology of lamellibranch tonic smooth muscle. These muscles are unique, not only for the fact that they are able to exert the largest known force for weight of muscle tissue, but also for their well-known ability to remain in the contracted state for prolonged periods of time with very little expenditure of metabolic energy (for a review, see Hoyle, 1964). While these muscles can also contract in a phasic manner, relaxing quickly after a brief twitch-like response, in some cases there is no histological differentiation to complement the functional dichotomy. It is therefore logical to inquire whether the different states of activity may have their bases in different types of excitatory synapses made with the muscle fibres by specific ‘tonic’ and ‘phasic’ motoneurons. Another suggestion (Takahashi, 1960) is that phasic responses occur following simultaneous activity in excitatory and inhibitory nerve fibres, the latter drastically limiting the duration of the contracted state of the muscle.
Stepping Patterns in Tarantula Spiders
Authors: Wilson Donald M. 
Published: April 2021

ABSTRACT
A descriptive model for the walking patterns of eight-legged animals similar to one applicable to some insects is presented. Data from films of walking tarantulas are compared to the gaits predicted by the model. The model is found to be inapplicable to the tarantula data in two important respects. Some of the common walking patterns of the tarantulas are not predicted by the model, and the several patterns found are not correlated with frequency differences. The tarantula gaits are best described in terms of the phase-relationships between leg pairs. Bilaterally opposite legs and segmentally adjacent legs tend to be used in antiphase. There is much phase variation, giving different stepping sequences, but this variation is by and large not correlated with speed. Incapacitation of some of the spider’s legs results in adaptive changes in phasecoupling between the other legs. A mechanistic model which could explain both insect and spider data is tentatively suggested. It is based on negative coupling between the oscillators controlling each leg.
Control of the Circadian Rhythm of Activity in the Cockroach
Authors: Brady John 
Published: April 2021

ABSTRACT
Harker has reported (i960) that the locomotor rhythm in the cockroach is maintained only if a secretion from the corpora cardiaca is delivered to the sub-oesophageal ganglion via the pair of small nerves connecting these two organs. Roberts has counterclaimed (1966) that neither this nerve nor the corpora cardiaca themselves are concerned in the control of the rhythm. It has been possible to confirm Roberts’s findings that these nerves can be severed, and much (possibly all) of the corpora cardiaca removed, without affecting the periodicity of the rhythm. Brief periods of enforced activity are shown to increase peak activity in the rhythm, whereas stress in the form of minor wounding depresses it. Cockroaches are found to maintain rhythmicity after the almost complete elimination of the medial neurosecretory cells from their brains. It is suggested that the differences between the views of Harker and Roberts concerning the influence of the corpora cardiaca may be explained in terms of the type of actograph used and the possibility that a cardiacum secretion controls the amount of activity but not its periodicity.
Control of the Circadian Rhythm of Activity in the Cockroach
Authors: Brady John 
Published: April 2021

ABSTRACT
Since 1955 Harker’s work on the control of cockroach activity rhythms by a hormonal clock in the sub-oesophageal ganglion has stood largely unchallenged, but recently Roberts (1966) has questioned several of her claims; in particular he finds it impossible to transfer rhythms by implanting this ganglion. Sub-oesophageal ganglia from rhythmic donors were implanted into 29 headless Periplaneta americana in a variety of ways and three different actographs used. In 2 cases the hosts showed bursts of activity for 2 or 3 days after implantation, roughly coincident with the donor’s previous rhythm; a further 8 implanted animals showed rather uncertain signs of an induced rhythm, but the remaining 19 were all apparently arrhythmic. Cauterization of the neurosecretory cells of the sub-oesophageal ganglion in situ showed that cockroaches can remain rhythmic in the absence of the cells described by Harker (1960 c), and probably in the absence of all cells in this ganglion which are stained by paraldehyde-fuchsin. Implantation of abdominal ganglia plus their respective neurohaemal organs (Brady & Maddrell, 1967) did not elicit rhythms in eight headless hosts. Cutting the circum-oesophageal commissures, or post-sub-oesophageal ganglion connectives, like beheading, appears to interfere seriously with the rhythmic expression of activity; one animal remained apparently rhythmic after this operation, however. Harker’s proposal for a second clock (1960b) requires that phase-shifts of less than 5 hr. shall be completed within a single activity cycle; this did not occur in the twelve cases observed, phase-shifting being gradual and taking several days before reaching the entrained steady-state. It is suggested that most of the divergent results of Harker, Roberts and Brady could be plausibly correlated if cockroaches have an electrical pace-maker in the brain co-ordinating rather ephemeral neuro-endocrine rhythms in the nerve-cord ganglia.
Conduction and Contraction in the Column of Hydra
Authors: Josephson Robert K. 
Published: April 2021

ABSTRACT
A suction electrode is described which allows long-term recording of spontaneous activity from essentially unrestrained Hydra. These electrodes were used to hold the animal while measuring column contractions and to measure the conduction velocity of the electrical potentials (contraction pulses = CPs) associated with contraction. CPs are conducted in the column at 3·4−8·1 cm./sec. The conduction velocity generally differs in the basal and hypostomal directions but the direction of faster conduction varies from animal to animal. The latency between CPs and measurable column contraction is 0·1−0·15 sec. During isometric contractions following single CPs there is a rapid tension rise reaching a peak in about 1 sec. which is usually followed by partial relaxation and then a second, slower tension rise. Available evidence indicates that both tension components are due to contraction of longitudinal musculature and both are activated by the same conducting system.