bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Metabolic Cost of Swimming in Ducks
Authors: Prange Henry D. , Schmidt-Nielsen Knut 
Published: April 2021

ABSTRACT
The metabolic cost of swimming was studied in mallard ducks (Anas platy-rhynchos) which had been trained to swim steadily in a variable-speed water channel. At speeds of from 0·35 to 0·50 m/sec the oxygen consumption remained relatively constant at approximately 2·2 times the resting level. At speeds of 0·55 m/sec and higher the oxygen consumption increased rapidly and reached 4·1 times resting at the maximum sustainable speed of 0·70 m/sec.. The maximum sustainable swimming speed of the ducks coincided with the limit predicted from hydrodynamic considerations of the water resistance of a displacement-hulled ship of the same hull length as a duck (0·33 m). The cost of transport (metabolic rate/speed) reached a minimum of 5·77 kcal/ kg km at a swimming speed of 0·50 m/sec. Ducks swimming freely on a pond were observed to swim at the speed calculated in experimental trials to give minimum cost of transport. Drag measurements made with model ducks indicated a maximum overall efficiency (power output/power input) for the swimming ducks of about 5%. Ships typically have maximum efficiencies of 20–30%. Because of the difficulty in delimiting the cost of swimming activity alone from the other bodily functions of the duck, overall efficiency may present an incorrect description of the swimming performance of the duck relative to that of a ship. An hydrodynamic parameter such as speed/length ratio whereby a duck excels conventional ships may present a more appropriate comparison.
Single-Session Learning by Octopuses
Authors: Wells M. J. , Young J. Z. 
Published: April 2021

ABSTRACT
In order to study the mechanisms of learning it is desirable to evolve techniques for evaluating long-lasting changes brought about by single events in the lives of animals. Techniques for the study of ‘one-trial learning’ are well known for vertebrates, but tend to involve learning not to perform some act that is followed by punishment. One-trial learning opens up the possibility of investigating the effects of electroconvulsive shock, spreading depression, anaesthetics, drugs and so on on the establishment of long lasting records in the central nervous systems.
Optomotor Responses and Nystagmus in Intact, Blinded and Statocystless Cuttlefish (Sepia Officinalis L.)
Authors: Messenger J. B. 
Published: April 2021

ABSTRACT
Evidence is reviewed confirming that the eyes of Sepia move under the influence of gravity, angular acceleration and visual receptors. Visual nystagmus and optomotor responses are described in free-swimming Sepia; these survive bilateral destruction of the statocysts, though they are abolished by blinding. Post-rotatory nystagmus is shown by intact animals in a plain background; in bilaterally blinded animals there are post-rotatory movements of the head. These responses disappear if the statocysts are removed. The post-rotatory nystagmus of intact animals is almost completely suppressed by visual cues. Other effects of blinding and statocyst removal are described.
Effects of Catecholamines On the Neuromuscular Junction of the Somatic Muscle of the EarthwormPheretima Communissima
Authors: Ito Y. , Kuriyama H. , Tashiro N. 
Published: April 2021

ABSTRACTEffects of catecholamines and adrenergic blocking agents on the neuromuscular junction of the somatic muscle of the earthworm, Pheretima communissima were studied by the microelectrode technique. Effects of catecholamines and their blocking agents on the post-junction membrane could be summarized as follows: (a) Adrenaline and isoprenaline (10−8–10−5 g/ml) hyperpolarized the membrane in proportion to the applied concentration. However, noradrenaline (10−8–10−5 g/ml) had no effect on the membrane potential, (b) Changes of the membrane resistance which appeared on treatment with catecholamines were in parallel with the changes of the membrane potential, (c) In the presence of excess calcium ions and in sodium-free (tris) solution, adrenaline and isoprenaline had no effect on the membrane potential or on the input resistance of the membrane. An increase of potassium ions and reduction of chloride ions had no relation to the actions of adrenaline and isoprenaline on the post-junctional muscle membrane, (d) Propranolol competitively inhibited the action of isoprenaline on the post-junctional muscle membrane but phentolamine had no effect on this action. Effects of catecholamines and their blockers on the m.e.j.p. and m.i.j.p. were observed, (a) After treatment with picrotoxin, the m.e.j.p. could be recorded in sodium-free solution. The frequency of the m.e.j.p. was increased by noradrenaline and adrenaline but not by isoprenaline. In normal Ringer’s solution isoprenaline slightly increased the frequency of m.e.j.p. but this appeared to be due to the effect of isoprenaline on the post-junctional membrane, (b) Phentolamine increased the mean amplitude of the m.e.j.p. but had no effect on the frequency of the m.e.j.p. After treatments with phentolamine effects of noradrenaline were inhibited, (c) After pre-treatment with d-tubocurarine, noradrenaline and adrenaline increased the frequency of the m.i.j.p. but only adrenaline increased the mean amplitude. Isoprenaline had no effect on the frequency but increased the mean amplitude of the m.i.j.p. From the above results it is concluded that the α-response to catecholamines increased the release of chemical transmitter from the nerve terminals; the β-response increased the membrane potential and the input resistance of the post-junctional muscle membrane. Both α-and β-responses to the catecholamines facilitated the transmission mechanism of the earthworm somatic muscle.
Function of the Supernumerary Sense Cells and the Relationship Between Modality of Adequate Stimulus and Innervation Pattern of the Scorpion Hair Sensillum
Authors: Sanjeeva-Reddy P. 
Published: April 2021

ABSTRACT
Mechanical stimulation of a single hair results in the discharge of four or five sense cells thereby refuting the classical generalization that mononeural innervation is characteristic of the mechanoreceptive hairs. By electrophysiological methods three functional units can be recognized: the ‘L’, ‘I’ and ‘S’ units. The ‘L’ unit conveys information about the duration and velocity of the dynamic phase; its discharge is phasic. The ‘I’ unit conveys information about the duration of the static phase and about the displacement of the hair; its discharge is tonic and the duration of discharge increases with extent of displacement. The ‘S’ unit is highly sensitive but responds only during the initial phase of displacement; if the hair is already extensively displaced the ‘S’ unit does not respond to further movement. These findings indicate that all the functional units may be meaningfully concerned in encoding the parameters of a mechanical stimulus. The widespread occurrence of multiple innervation of receptors, and its functional significance, is discussed; and a thorough re-investigation of stimulus—response relationships in the mechanoreceptive hairs of arthropods is advocated.
Oxygen Uptake and Transport by the Rainbow Trout During Exposure to Carbon Monoxide
Authors: Holeton George F. 
Published: April 2021

ABSTRACT
Rainbow trout, brown trout and pike were exposed to 5% carbon monoxide which was sufficient to combine with over 90% of their haemoglobin. Trout tested at 10 and 15°C did not survive exposures to carbon monoxide longer than 30 min, but those tested at 5°C survived exposures of up to 3 h. Even at 5°C the trout were weakened and unable to stay upright. The respiratory responses of trout exposed to 5% carbon monoxide at 5°C for 30 min were examined in detail. The trout responded to carbon monoxide with an increase in the flow of blood and water past the gills. As a result the mean partial pressure gradient of oxygen from water to blood across the gill membrane was increased. In spite of these changes oxygen uptake fell by 40%. An increase was observed in heart rate and blood pressure in both the ventral and dorsal aorta of CO-exposed fish. There was a drop in the oxygen diffusing capacity or transfer factor of the gills of CO-exposed trout. Although the fish were rendered anoxic there was no bradycardia, suggesting that this reflex response depends upon either environmental or arterial PO2 and not upon arterial oxygen content. The observed responses to carbon monoxide may be a result of either anoxia, anoxaemia, reduced pH, or a combination of these factors
The Control of Sodium Uptake by the Larva of the Mosquito Aedes Aegypti (L.)
Authors: Stobbart R. H. 
Published: April 2021

ABSTRACT
The time-course of the fluxes causing net sodium uptake through the anal papillae, and the control of this uptake, have been studied in fed sodium-deficient fourth-instar larvae of the mosquito Aëdes aegypti in 2 mM/1 NaCl. Influx, outflux and uptake rate all decline exponentially with time, suggesting that effective negative feedback operates continually upon the transporting system. Uptake is impaired or eventually stopped when certain tissues are destroyed, or ligatured or clamped out of the circulation. The effect is not explicable in terms of impaired circulation of haemolymph through the papillae, and is taken to indicate that a hormone is involved in sodium uptake. Interruption of the nerve cord suggests that an abdominal monitoring centre conveys information forwards along the nerve cord to a control centre in the thoracic ganglia to inhibit or increase hormone production. The hormone is apparently produced by the thoracic ganglia and the retro-cerebral complex (corpora allata and homologues of the prothoracic glands combined). Evidence that a second hormone, produced in the head, is also involved in sodium uptake is at present inconclusive. A possible mechanism of hormone action is suggested and discussed in relation to what is known of the functioning of the ionic carriers in the anal papillae.
The Central Nervous Control of Colour Change in the Minnow (Phoxinus Phoxinus L.)
Authors: Gentle Michael J. 
Published: April 2021

ABSTRACT
A series of ablations were carried out in the optic tectum of the minnow, Phoxinus phoxinus, in order to investigate its importance in colour change. The presence of the anterior or posterior tectum alone one on or both sides caused persistent pallor in normal fish. The presence of the anterior tectum on one side and the posterior on the other enabled the fish to adapt chromatically to its background. Small bilateral removals from the dorsal part of the optic tectum did not effect colour change. Larger removals from the dorsal tectum reduced the extent of change and still larger removals caused the fish to pale on all backgrounds.
Sun Navigation in Homing Pigeons—Attempts to Shift Sun Coordinates
Authors: Walcott Charles , Michener Martin C. 
Published: April 2021

ABSTRACT
Small time errors in the biological clocks of pigeons appear to have no effect on their navigation. An error of 2 h seems to shift the pigeons’ orientation as predicted by a suncompass hypothesis, but 6 h shifts gave initial orientation that was too scattered to analyse. Alteration of the apparent sun altitude with mirrors at the loft was without effect on navigation. The administration of 30% D2O in the pigeon’s drinking water combined with a random light schedule and holding at a westerly point had no effect on the pigeon’s homing. We conclude that the pigeon’s navigation is probably not based on either the sun or on accurate sense of time at the home loft.
Acoustic Location of Prey by Barn Owls (Tyto Alba)
Authors: Payne Roger S. 
Published: April 2021

ABSTRACT
Barn owls (Tyto alba) can locate prey in total darkness using only the sense of hearing, with an error of less than 1° in both the vertical and horizontal planes. Differences between the behaviour of barn owls flying at prey in complete darkness (analysed from films taken under infra-red illumination) and their behaviour in the light are correlated with the problems they must face in acoustic orientation. Experiments with owls trained to strike a concealed loudspeaker show that they depend on frequencies of sound above 5 kHz. Measurements of sound pressure in the region of the owl’s eardrum, made with a probe-tube microphone while moving a loudspeaker around the owl’s head, reveal that for frequencies above 8-5 kHz the ear is highly directional. At such frequencies, regions of high sensitivity (tightly isolated by peripheral regions of low sensitivity) are directed along different paths for the two ears. These regions of good sensitivity are correlated with the asymmetry of the barn owl’s external ears. Movements of a flap of skin in front of the ear opening changes the overall directional sensitivity patterns by redirecting the regions of maximum sensitivity. A theory is presented to explain how a barn owl might locate the position of a sound source by moving its head until the intensity of all frequencies comprising a complex sound is brought to a maximum in both ears (aided perhaps by differences in inter-aural time delay that are enhanced by intensity disparities).
Rhythmic Activity in the Insect Nervous System
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
Spiracle 1 of Sphodromantis lineola possesses a moveable valve equipped with two closer muscles which act as synergists, receive identical innervation but act on different regions of the valve. The two muscles are controlled by two motor axons which produce simultaneous small EPSPs in the two muscles of the left and right spiracles. Valve activity can be facultatively coupled to the abdominal ventilatory rhythm. Three patterns of coupling have been recognized. Ventilation-coupled activity includes burst formation. Similar repetitive bursts can be produced in the spiracle nerves of an isolated segment by treatment with CO2 and by mechanical stimulation.
The Role of the Lateral-Line Efferent System in Xenopus Laevis
Authors: Russell I. J. 
Published: April 2021

ABSTRACT
Efferent impulses have been recorded from branches of lateral-line nerves. The functional significance of the efferent innervation and its action on afferent impulse activity has been examined. Neither mechanical stimulation of the lateral-line receptors nor electrical stimulation of afferent nerves excites lateral-line efferent activity. Trains of efferent impulses accompany all active movements for their duration. In immobilized animals a close correlation exists between impulses in lateral-line efferent nerve fibres and motor impulses in ‘large’ nerves innervating ‘twitch’ muscles, but not with impulses in nerves innervating ‘slow’ muscles. A close similarity also exists between impulse activity in different lateral-line efferent fibres. Whereas electrical stimulation of ascending tracts in the spinal cord fails to excite lateral-line efferent fibres, stimulation of the spinal cord in the region of descending reticular motor axons causes efferent impulses to follow each pulse after brief, constant, latencies. It is suggested that the efferent neurones may be innervated by axon collaterals from reticular cells. Electrical stimulation of efferent fibres innervating a lateral-line receptor produces transitory inhibition of impulse activity in the afferent nerve fibres. The inhibition has a long variable latency (11-30 ms) and persists for 40-60 ms. Upon cessation of inhibition, caused by a train of efferent impulses, afferent impulses reappear at an accelerated frequency (after-discharge), and quickly return to resting frequency. A role of the lateral-line efferent neurones during active movement is discussed.
A Preparation of Aplysia Fasciata for Intrasomatic Recording and Stimulation of Single Neurones During Locomotor Movements
Authors: Weevers R. De G. 
Published: April 2021

ABSTRACT
Methods are described for suspending and clamping Aplysia fasciata so as to permit intrasomatic recording from neurones of the head ganglia during locomotor and other behavioural activities. Sensory responses of neurones in the pedal ganglion are classified into four main types, all being distinct from those of pleural ganglion cells. The pedal ganglion may well contain ‘motor cells’ for the greater part of the somatic musculature. Preliminary results suggest that the pleural LGC may be involved in promoting a change from swimming to creeping behaviour.
Observations of the Effects of Changes in Hydrostatic Pressure and Illumination On the Behaviour of Some Planktonic Crustaceans
Authors: Lincoln R. J. 
Published: April 2021

ABSTRACT
Daphnia magna responds vigorously to a large increase in hydrostatic pressure when in total darkness, but this response is very much depressed in the presence of light. The weak response of Daphnia in light is apparent over a wide range of intensity. The effect of pressure on Daphnia appears to be largely kinetic and does not involve a specific orientation of the swimming activity. The overt threshold for Daphnia and Calanus under laboratory conditions are in the region of 3.5 bar (50 p.s.i.) and 0.7 bar (10 p.s.i.) respectively. The barosensitivity is not abolished by repetitive compression and decompression. Observations made of the behaviour of Calanus indicate that the pressure response is not inhibited by light as it is in Daphnia. Calanus which have been maintained at high ambient pressure for several hours remain sensitive to small increments of pressure. The response appears similar to that obtained at the level of atmospheric pressure.
Behavioural Physiology of the Colonial Hydroid Obelia
Authors: Morin James G. , Cooke Ian M. 
Published: April 2021

ABSTRACT
Spontaneous electrical potentials from Obelia geniculata hydranths were recorded using fine-tipped suction electrodes. The primary behavioural responses of the hydranths were observed and correlated with specific electrical potentials: the contraction potential (KP) associated with hydranth withdrawal, the mouth-opening potential (MOP) associated with mouth opening, and the tentacle contraction potential (TKP) associated with oral flexion of individual tentacles. KPs occurred in rhythmic bursts while the TKP and MOP responses were infrequent and non-rhythmic. Two other species, O. longissima and Gonothyraea loveni, were shown to produce the same three types of potentials with corresponding behavioural responses. .The MOP activity may occasionally drive the KP responses within a hydranth, but the coupling is very loose. None of the other possible interactions within a hydranth was observed. .No interaction of any of the potentials between adjacent hydranths was found in the absence of external stimuli. .It seems likely that the KPs in Obelia are homologous with the contraction potential (CP) in Hydra and the hydranth potential (HP) in Tubularia. MOP and TKP activity do not show apparent homologies with potentials of the other hydroids Hydra, Tubularia and Cordylophora.
The Visual Mechanisms of Tenebrio Molitor: Changes in the Electroretinogram as Function of the Stimulus Duration
Authors: Yinon U. 
Published: April 2021

ABSTRACT
The ERG complex of the compound eye of the yellow mealworm bettle Tenebrio molitor (L.) separates into two components with stimulus durations of longer than 100 ms. These are the ‘on’ and the ‘off’ effects. Above stimulus durations of 1 s the positive potential following the ‘on’ is faster and the positive ‘off’ is followed by a small negative one. The latent period of the ‘on’ is independent of the stimulus duration while for stimulus durations of longer than 300 ms the ‘off’ latency is coupled with the end of the stimulus. If measured after the extinction of the stimulus the ‘off’ latency is affected by the stimulus duration. The ‘on’ and ‘off’ amplitudes behave similarly for various stimulus durations. Both originate in the receptor cells. The Bunsen-Roscoe Law of photochemistry holds for stimulus durations of 10-40 ms. For a given intensity, the amplitudes diminished for durations longer than 300 ms.
The Effect of Light Regimes On the Circadian Rhythm of Flight Activity in the Mosquito Aedes Taeniorhynchus*
Authors: Nayar J. K. , Sauerman D. M. 
Published: April 2021

ABSTRACT
The flight activity patterns of groups and individuals of sugar-fed A. taeniorhynchus females have been studied under different light regimes, by recording of flight sound as an indicator of flight activity. In an LD 12:12 regime, flight activity occurs both at light-off and light-on, forming a bimodal ‘alternans’ pattern. This basic pattern of flight activity persists with a periodicity of 23.5 h under continuous DD, but under continuous LL is masked over by irregular excessive outbursts of activity. The flight activity rhythm originates for the first time in the adult stage, and it is not carried over from rhythms of developmental stages. Flight activity rhythms can be entrained to a new light regime within 24 –36 h which is rather fast. An early light-off does not reset the phase of the rhythm, but a delayed light-off does. The flight activity rhythm can be entrained to 24 h light regimes other than LD 12:12. But a single stimulus of less than 12 h is not effective in initiating the bimodal circadian rhythm. Frequency demultiplication within certain limits can entrain the flight activity rhythm to 24 h. This flight activity rhythm of A. taeniorhynchus is compared with the activity rhythms of Aopheles gambiae and Culex pipiens pallens. It is concluded that the basic bimodal alternans pattern of flight activity is a persistent property of the circadian oscillating system, which suggests that other activity rhythms involving flight are dependent on the same rhythm.
A Quantitative Study of the Ionic Basis of Extraneuronal Potential Changes in the Central Nervous System of the Cockroach (Periplaneta Americana L.)
Authors: Pichon Y. , Moreton R B. , Treherne J. E. 
Published: April 2021

ABSTRACT
Measurements have been made of the extraneuronal potential changes produced by replacement of sodium ions with other organic and inorganic cations in the solution bathing isolated abdominal connectives. On the basis of the observed extraneuronal potential changes it is possible to arrange monovalent cations in the following sequence of effectiveness: It is concluded that the ionic dependence of the extraneuronal potentials is similar to that of a theoretical model system consisting of a perineurial diffusion barrier in series with a long, narrow channel representing the system of intercellular clefts connecting the inwardly facing surface of the perineurium with the extraaxonal fluid. On the basis of this model the effect of high external concentrations of, for example, potassium ions would be to depolarize the outwardly facing perineurial cell membranes. The considerable departure of the observed potentials from the values predicted by the Nernst equation can be accounted for in terms of the short-circuiting effect, due to the finite ionic permeability of the tight junctions between perineurial cells. Qualitative predictions can also be made concerning the rates of movement of potassium and sodium ions in the extracellular system.
Innervation of the Abdominal Intersegmental Muscles in the Grasshopper
Authors: Tyrer N. M. 
Published: April 2021

ABSTRACT
Extracellular records from the motor neurones to the median internal dorsal muscles (abdominal intersegmental) of Melanoplus differentialis have been made simultaneously with intracellular records from the muscle fibres. Four types of PSP have been recorded intracellularly: type 1, a large PSP with a regenerative response and a small overshoot; type 2, a PSP of between 5 and 15 mV; type 3, a PSP of between 1 and 5 mV; type 4, a hyperpolarizing PSP of up to 5 mV. Although there is variation in the size of the spikes recorded en passant, the four types of PSP can generally be correlated with large, medium, small and very small spikes. Evidence is presented to demonstrate that there are two motor units for each type of PSP in the dorsal intersegmental muscles. Each muscle appears to have a mixture of muscle fibres of each unit. This is consistent with the anatomical finding of eight motor neurones supplying the muscles.