bluuebunny/crossref_metadata_2025 huggingface dataset:
Conduction Velocities and Their Temperature Coefficients in Sensory Nerve Fibres of Cockroach Legs*
Authors: Chapman K. M. , Pankhurst J. H.
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Homing of Single Pigeons—Analysis of Tracks
Authors: Michener Martin C. , Walcott Charles
Published: April 2021

Pigeons trained by releases along a constant compass line were repeatedly tracked to their lofts from the same training points 30-50 miles away. Their tracks differed from day to day by several miles, and the birds usually did not follow any obvious landmarks. The pigeons were released from new release points and on many of the tracks followed a definite sequence of orientation methods: the birds began flying in the same compass direction that had got them home from the training point, then they apparently switched to a rather accurate navigation method which got them to within 10 miles of the loft, where they seemed to pilot by a few familiar landmarks to the loft entrance. There is no evidence that most of the pigeons learned or could use landmarks extensively more than 10 miles from the loft, even over area which they crossed more than twenty times. The flight of pigeons from the training points and new release points at distances of 13 miles or more depended strictly on the visibility of the sun.
Spontaneously Induced Rhythm of Tidal Periodicity in Laboratory-Reared Carcinus
Authors: Williams Barbara G. , Naylor E.
Published: April 2021

Laboratory-reared shore crabs show circadian rhythmicity which is transformed to approximate tidal rhythmicity after a period of chilling to 4° C. Periodogram analysis of the results characterizes the periodicity of the two types of rhythm, which suggest that the ability to show a rhythm of tidal periodicity is an inherited feature of shore-crab physiology.
Propulsion by Hispid Flagella
Authors: Holwill M. E. J. , Sleigh M. A.
Published: April 2021

Equations are derived for the propulsive velocities and power dissipation of undulating hispid flagella. The observed rates of movement of water around the flagella of two chrysomonad flagellates and the translational speed of Ochromonas malhamensis agree closely with values calculated if it is assumed that the flagellar mastigonemes remain perpendicular to the flagellar surface and that these mastigonemes lie in two diametrically opposed rows situated in the plane of the flagellar wave.
Muscle Activity During Flight in Some large Lepidoptera
Authors: Kammer Ann E.
Published: April 2021

The names and functions of the main mesothoracic flight muscles in Lepidoptera are reviewed. The wingbeat period in satumiid moths and monarch butterflies is long and variable. The three parameters, wingbeat period, burst length (number of times a motor unit is activated per wingstroke) and stroke amplitude are interdependent and positively correlated. Partial amputation of the wings in satumiids decreases wingbeat period. Cutting the sensory nerves from the wings increases the period. These results indicate that the influence of wing movement on wingbeat period is mediated by receptors near the base of the wing. The central nervous mechanisms which generate motor patterns during flight in Lepidoptera are discussed and compared with those in locusts. It is proposed that both mechanisms can be described by a single model, with minor differences in the mechanism of burst production.
The Relationship Between Blood Ions and Blood-Cell Density in Insects
Authors: Brady John
Published: April 2021

Pairs of blood samples were taken from individual Periplaneta americana, the first sample being used for a live-blood haemocyte count and the second (collected 10 sec. later) for potassium and sodium determinations. Analysis of these matched data on cell count and whole-blood ion concentration reveals a positive correlation between the haemocyte density and the potassium concentration, the mean regression coefficient being +0·83 mM K+/1. of blood for 10,000 cells/μl. Similar analysis of the sodium data gives a negative correlation, with a mean regression coefficient of − 1·69 mM N+/1. for 10,000 cells/μl. Haematocrit estimations on heat-fixed blood, whose haemocyte density was simultaneously determined, indicate a mean haemocyte volume of 720 μ3. If the correlations relate entirely to the contents of the haemocytes, comparison with the haemocyte volume would indicate that the cell sap contains 115 mM/1. of potassium and probably less than about 60 mM/1. of sodium ; these levels are very similar to those reported for other tissues of the cockroach. Since cockroach blood contains relatively little potassium these figures suggest that a significant proportion of the whole-blood potassium may be contained within the haemocytes and so not be immediately available physiologically. Wounding is found to raise the haemocyte density by up to 4 times; at the same time the whole-blood potassium concentration rises and the sodium falls. A table is given comparing haemocyte counts and potassium levels in the blood of six closely studied insect species, the information having been compiled from different sources in the literature.
Current-Voltage Relations in the Isolated Giant Axon of the Cockroach Under Voltage-Clamp Conditions*
Authors: Pichon Y. , Boistel J.
Published: April 2021

An experimental method of recording and controlling the membrane potential of a small area of the membrane of the cockroach giant axon is described. The recorded action potentials were essentially similar to those previously recorded by other methods. The membrane currents resemble those reported for the squid axon, the node of Ranvier in frog nerve and the lobster giant axon. Small cathodal polarizations gave only small outward currents; larger depolarizations (10–100 mV.) gave an initial inward current which changed into a delayed outward current. The initial inward current attained a maximum with depolarizing pulses of 40-50 mV. and showed a reversed, outward, flow of about 100 mV. Delayed outward currents increased continuously with increasing impulse voltage. The initial inward current was larger when the pulse was preceded by an hyperpolarizing prepulse. It is concluded that, although the early inward currents were in all probability related to Na+ ions and the delayed outward currents to K+ ions, the possible participation of Ca2+ and Cl− ions to the ionic currents cannot be excluded.
Short-Term Learning and Interocular Transfer in Detour Experiments with Octopuses
Authors: Wells M. J.
Published: April 2021

Octopuses will make detours down a corridor with opaque walls and will make a correct left-right choice at the far end in order to attack a crab seen to one side of the passage through the transparent windows of a home compartment. In all, 1071 trials were carried out. In 883 of these a detour was completed, rightly or wrongly; in the remaining trials the octopuses failed to complete detours within 5 min. of the start of the trial. The percentage of errors rose with the time spent in the maze. Animals that completed their runs within 20 or 30 sec. of entering the corridor rarely made a mistake; animals that took 2 min. or more, whether due to imposed delays (animal shut in the corridor) or to slow exploration of the maze, made as many errors as correct responses. After removal of the vertical lobe from the brain the octopuses made more errors, particularly in the slower runs. There was also a higher proportion of trials at which they failed to complete a detour at all. These failures are not due to a failure of interocular transfer or to locomotor defects. The results are discussed in relation to the function of the vertical lobe, interocular transfer, the nature of representations of recent events within the optic lobes and the establishment of more permanent memory traces in discrimination experiments.
Integration of Visual Stimuli by the Crayfish Central Nervous System*
Authors: Wiersma C. A. G. , Yamaguchi T.
Published: April 2021

For the crayfish, properties of visually reacting intemeurone types in the optic nerve are described on the basis of single-unit analysis. Sustaining fibres show : (a) ‘surround’ inhibition over the whole retina, including the excitatory field; (b) ‘on’ and ‘off’ effects at field boundaries; (c) a dark discharge in deteriorated preparations; (d) an increase in adapted firing rate and response to flashes in an ‘excited state’ of the preparation; (e) increased overall impulse frequency to fast-moving shadows at frequencies of 2–10/sec. which elicit short bursts. Dimming fibres, having mainly reversed properties, show: (a) bursts followed by adaptation to a lower ferquency level of spikes on light dimming; (b) total inhibition by illumination for times proportional to light intensity; (c) responsiveness to quickly moving shadows. ‘Jittery’ movement fibres lack directional sensitivity. Forthem: (a) total illumination and contrast have, within a wide range, no effect on discharges to moving targets; (b) large, dark cards moved at constant speed are seen only near their visual field boundary; (c) the less predictable the movement of a small dark object is, the longer its excitatory effect lasts; (d) responsiveness of field parts exposed is decreased for long durations; (e) no firing is caused by active or passive eye motions. Space-constant fibres show changed location and size of their excitatory fields with eye position. Their potential visual fields below the horizontal plane are un-responsive, due to inhibition caused mainly by statocyst input. Two eye muscle motor fibres, also under statocyst control, are influenced by fight on the limited sensory fields of two pairs of identifiable sustaining fibres. The two motor fibres, which innervate antagonistic muscles, are reversely excited and inhibited by these fields.
Temperature Acclimation of the Functional Parameters of the Giant Nerve Fibres in Lumbricus Terrestris L
Authors: Lagerspetz Kari Y. H. , Talo Antti
Published: April 2021

Temperature acclimation in poikilotherms has been the subject of several recent reviews and symposia. Many of the acclimation phenomena occurring at the organismal or organ level have been shown to be accompanied by corresponding compensatory cellular changes. However, only in a few instances has thermal acclimation also been demonstrated to occur in isolated surviving tissues of animals (Precht & Christophersen, 1965; Lagerspetz & Dubitscher, 1966; Schlieper, 1966). In these cases of acclimation the mechanism of acclimation thus operates on the cellular or tissue level.
Temperature Acclimation of the Functional Parameters of the Giant Nerve Fibres in Lumbricus Terrestris L
Authors: Talo Antti , Lagerspetz Kari Y. H.
Published: April 2021

The effect of temperature on the refractory period in nerve fibres is of the same magnitude as its effect on the duration of the action potential (Tasaki, 1949) or as the effect of temperature on the duration of the falling phase of the spike (Adrian, 1921). Temperature coefficients (Q10) as high as 4 have been calculated for the refractory period in single fibres of the frog by Schoepfle & Erlanger (1941). According to Tasaki (1949), the Q10 value of the absolute refractory period is about 3·5 for a single node in the myelinated fibres of the frog, when determined for the temperature interval 13·7-19° C.
The Circadian Flight Activity of the Mosquito, Anopheles Gambiae: Phase Setting by the Light Regime
Authors: Jones M. D. R. , Hill M. , Hope A. M.
Published: April 2021

The circadian cycle of flight activity of individual, sugar-fed, Anopheles gambiae females has been studied, using the flight-sound as an indicator of activity. In an LD 12:12 régime (alternating 12 hr. light: 12 hr. dark), activity peaks follow both light-off and light-on. The mosquitoes are moderately active in the dark, but are inactive in the light after the first half-hour. If the light period is extended, the activity is delayed until light-off. Light appears to have an inhibitory effect, but the insects may show some activity towards the end of a 48 hr. light period. Cyclical activity continues in constant dark with a period of approximately 23 hr. A late light-off resets the cycle; an early light-off does not. When the LD 12:12 régime is advanced by 6 hr. the cycle is re-entrained within 2−3 days. Light in the second half of the subjective night appears to advance the cycle. It is suggested that the activity is controlled by an endogenous rhythm which possibly controls the release of an excitatory hormone. The effect of light may be mediated through an inhibitory hormone.
Sodium, Chloride and Water Balance of the Intertidal Teleost, Xiphister Atropurpureus
Authors: Evans David H.
Published: April 2021

Studies were undertaken to determine the degree of regulation of sodium, chloride and water displayed by the intertidal teleost, Xiphister atropurpureus, over a range of salinities. The plasma concentrations of sodium and chloride declined by approximately 15 % in 10 % sea water (48 mM-Na/kg.) and the intracellular and extracellular spaces increased by approximately 6% in 10% sea water.
Sodium, Chloride and Water Balance of the Intertidal Teleost, Xiphister Atropurpureus
Authors: Evans David H.
Published: April 2021

The rate of loss of sodium, chloride and water via the urine and the rate of intake of sodium, chloride and water by ingestion of the medium was determined for the euryhaline teleost, Xiphister atropurpureus. The urinary losses of sodium and chloride were approximately 0·5 mM/kg. fish/day in both 100% sea water (480 mM-Na/kg.) and 10% sea water. The ingestion of sodium and chloride by drinking the medium amounted to approximately 4 mM/kg. fish/day in 100% sea water and approximately o-i mM/kg. fish/day in 10% sea water. The low rate of urine flow in 10 % sea water and the low drinking rate in 100 % sea water indicate a relative impermeability to water in both salinities.
Respiration and Tracheal Ventilation in Locusts and other Flying Insects
Authors: Weis-Fogh Torkel
Published: April 2021

In small insects there is no need for respiratory movements because the rate of diffusion of oxygen and carbon dioxide is adequate even during flight, but when the thorax is more than a few millimetres in diameter the primary tracheae or the air sacs which supply the wing muscles must be ventilated (Weis-Fogh, 1964b). Apart from various auxiliary mechanisms described by Miller (1960 a, 1964), the respiratory movements are of two different types: the well-known abdominal movements which result in abdominal pumping of air and haemolymph and the little-known movements of the thoracic walls which are caused by the wing movements themselves and which result in thoracic pumping at wingstroke frequency (Weis-Fogh, 1956a, 1964a). The existence of a thoracic mechanism has been suspected for a long time (du Buisson, 1924; Krogh, 1941; Krogh & Zeuthen, 1941) but was denied by Fraenkel (1932a) who investigated the abdominal respiratory movements and their control in a variety of large insects during tethered flight. Lack of suitable methods seems to have prevented further studies.
Active Transport by the Cecropia Midgut
Authors: Harvey W. R. , Haskell J. A. , Nedergaard S.
Published: April 2021

From two lines of evidence, we conclude that the potassium transport gives rise directly to the midgut potential, i.e. that the active potassium transport mechanism is electrogenic. First, diffusion potentials of neither potassium, sodium, magnesium, calcium, nor chloride could give rise to the large midgut potential if values for tissue concentrations are accepted for their respective activities in the epithelium. Secondly, no externally added cation other than potassium is required to sustain either the potential or short circuit current, no specific anion is required, and no metabolic ion is known to be produced in sufficient amount to act as a counter ion for potassium in a non-electrogenic process. Changes in the concentration of potassium on the blood-side of the midgut always lead to changes in potential in the direction predicted by the Nernst equation. Moreover, a tenfold change in potassium concentration leads to the expected 59 mV. potential change provided that the prior midgut potential is at least 130 mV. This effect could be attributed either to the stimulation of an electrogenic potassium pump or to a potassium diffusion potential across the blood-side barrier.
Some Observations on the Role of the Body Wall of Acanthocephalus Ranae in Lipid Uptake
Authors: Hammond R. A.
Published: April 2021

Acanthocephalus ranae has been found to take up glyceryl tri[oleate-9,10-3H] solely through the surface of the trunk. The proboscis and lemnisci play no part in the uptake of this material. The large amounts of lipid present in the latter organs may be evidence of their involvement in lipid excretion. Fat-soluble dyes are taken up by the animal and accumulate in lipid droplets in the lemnisci and proboscis wall. It is suggested that such dyes do not enter the animal through the surface of the proboscis, as has been suggested previously, but through the surface of the trunk. The structure of the acanthocephalan body wall is discussed in relation to the uptake of nutrients.
The Electrical Activity of the Radial Nerve in Diadema antillarum Philippi and Certain Other Echinoids
Authors: Millott N. , Okumura H.
Published: April 2021

The propagated massed potentials which follow stimulation of the radial nerve in Arbacia, Diadema, Echinus and Paracentrotus are described. Approximate values for the averaged absolute and relative refractory periods and the conduction velocity were obtained. The response of Diadema has a double peak which is shown to represent responses of nerves differing in excitability and conduction velocity. The fast potential is concerned with spine movement. The slow potential is related to inhibition of spine movements excited photically.
The Location of Penetration Barriers in the Ganglia of the American Cockroach, Periplaneta americana (L.)
Authors: Eldefrawi M. E. , Toppozada A. , Salpeter M. M. , O’Brien R. D.
Published: April 2021

The nature and location of the barrier system which partially protects the nervous system in insects has been investigated in the American cockroach by studying the fluxes of 14C-butanol, 14C-butyrate, 14C-butylamine and 3H-butyltrimethylammonium. Disruption of the sheath covering the ganglia has little effect on the influx of butanol and butyrate, but increased that of butylamine and butyltrimethylammonium. 2,4-Dinitrophenol slowed the influx of only those compounds whose metabolism it blocks. Effluxes show a fast and a slow component. Disruption of the sheath increases the amount but not the rate of the fast component; it raises the rate of the slow component for butanol, butyrate and butyltrimethylammonium, but not always. Nerve cords stained with methylene blue and freeze-sectioned show dye concentrated in the fat tissue surrounding the nerve cord, then in the neural lamella; a little penetrated the cell bodies of glia and neurones, but the neuropile was unstained. These findings suggest that the external sheath plays some part in restricting cation influx; apart from this the barrier system is a function of the whole ganglion, except that the neuropile may enjoy special protection.
Sodium Regulation in the Amphipod Gammarus duebeni Lilljeborg from Freshwater Localities in Ireland
Authors: Sutcliffe D. W. , Shaw J.
Published: April 2021

A quantitative study of sodium influx and loss was made on populations of Gammarus duebeni obtained from four freshwater localities in Ireland. Characteristic features of sodium regulation in animals from the four localities were as follows, (a) The sodium influx increases gradually with increasing external sodium concentrations, but a maximum (saturation) level is abruptly reached at an external concentration of 1−2 mM/l. and the transporting system is half saturated at about 0·5 mM/l. sodium. (b) Over the range of sodium concentrations found in fresh waters a low rate of sodium uptake is sufficient to balance sodium losses at concentrations down to between 0·5 and 0·25 mM/l. At lower concentrations the influx is increased and the loss rate is reduced, (c) Calculations suggest that hypotonic urine containing approximately 40 mM/l. sodium is produced at external concentrations ranging from fresh water to 40 % sea water. At external concentrations below 0·25 mM/l. sodium the urine concentration is probably reduced to well below 40 mM/l. sodium. A detailed comparison is made of sodium regulation at external concentrations ranging between 0·07 and 1 mM/l. sodium in G. duebeni from fresh water in Ireland and from fresh water and brackish water in Britain. It is suggested that G. duebeni in Ireland constitutes a distinct physiological race adapted for living in fresh waters with relatively low sodium concentrations.
Motor Neurone Coupling in Locust Flight
Authors: Kendig Joan Johnston
Published: April 2021

Techniques are described for recording in locust thoracic ganglia from single units identifiable as the motor neurones of specific flight muscles. There are at least two kinds of excitatory interactions among flight-muscle motor neurones. A spike in one motor neurone may be electrically transmitted to another with little delay but much attenuation. Stimulation of a group of motor neurones produces a second, probably chemically transmitted, potential with a latency of 5−6 msec. No short-term inhibitory interactions between motor neurones were observed. Activity in one motor unit of the flight system has long-term effects on the motor neurones of other units, excitatory in some cases and inhibitory in others. Single impulses in sensory neurones have little effect on motor neurones; sustained sensory input to a motor neurone produces a slow depolarization and increase in impulse frequency. Antidromic impulses in one group of motor neurones can entrain orthodromic impulses in another motor neurone. These data are discussed with reference to the hypothesis that the pattern of locust flight—rhythmic synchronous bursts of synergist activity, strict alternation between antagonists—can be produced by motor neurone interactions alone.
Influence of Temperature on the Transmembrane Potential of Ascaris Muscle Cells
Authors: DeBell Jean T. , Sanchez V.
Published: April 2021

It has been shown that there is an almost linear inverse relationship between the transmembrane potential of the somatic muscle cells of Ascaris lumbricoides and the bath temperature between 38° and 20°C. It has also been shown that the spike frequency reflects these changes, decreasing at a rate of 0·6 impulse/sec./mV. D-Tubocurarine interferes with the response of these cells to thermal changes between 38° and 20° C. but it is ineffective below 20°C. It is proposed that the presynaptic nerve fibres are responsible for the thermal sensitivity of the muscle cells, since the amount of depolarizing neurohormone spontaneously released at the neuromuscular junctions would depend upon the temperature.
Studies on the Absorption and Metabolism of D-(u-14C) Glucose by Polymorphus minutus (Acanthocephala) in vitro
Authors: Crompton D. W. T. , Lockwood A. P. M.
Published: April 2021

The absorption and initial metabolism of glucose by the acanthocephalan Polymorphus minutus have been studied in vitro under conditions designed to approximate to those in vivo. The results of the investigation of the absorption of glucose are compatible with the assumption that a carrier system is involved in the transport of glucose. The carrier system is half-saturated at an external glucose concentration of about 0·25 mg./ml. and is tending towards full saturation when the external glucose concentration reaches 2·0 mg./ml. P. minutus has been shown to be capable of absorbing glucose against a concentration gradient. The rate of glucose absorption, at a given glucose concentration, has been found to fall when the worms have been acclimatized to that concentration. It has been estimated that P. minutus requires about 4 μg. glucose/mg. wet weight of worm/hr. in vivo, assuming that the external glucose concentration is at least 2·0 mg./ml. After 4 hr. incubation with radioactive glucose the radioactive label has been detected in a variety of metabolites extracted from the worms. Evidence is presented indicating that these include : glucose, sugar phosphates, maltotriose, UDPG, glycogen, amino sugars, amino acids and organic acids. Trehalose has not been detected in P. minutus, and a possible evolutionary significance of this result is discussed.