bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Ephestia Kuehniella on the Development of its Parasite Nemeritis canescens
Authors: Corbet Sarah A. 
Published: April 2021

ABSTRACT
The first larval instar of Nemeritis lasts longer in young caterpillars of Ephestia than it does in older caterpillars. First-instar Nemeritis larvae in young hosts feed and grow very slowly, but they remain capable of fast growth if transferred to older host caterpillars. Measurements of the protein concentration, the amino acid concentration and the freezing-point depression show rapid changes in the composition of the haemolymph of Ephestia caterpillars at that stage of larval development at which they first become capable of supporting the fast development of first-instar larvae of Nemeritis. It is suggested that the rate of development of Nemeritis larvae depends on their rate of feeding, and that their rate of feeding is determined by a behavioural response to the composition of their food, the host’s haemolymph; they feed slowly in young host caterpillars because the concentration of solutes (notably amino acids) in their food is so high. A similar situation may hold when the development of insect parasites is delayed in diapausing hosts.
The Patterns of Renal Electrolyte Excretion in the Duck (Anas platyrhynchos) Maintained on Freshwater and on Hypertonic Saline*
Authors: Holmes W. N. , Fletcher G. L. , Stewart D. J. 
Published: April 2021

ABSTRACTThe renal excretion of water and electrolytes was examined in starved ducks maintained on fresh water and on hypertonic saline containing 284 mM/l. NaCl and 6·0 mM/l. KCI. No significant differences were observed in the urine flow, glomerular filtration rate, renal plasma flow and the excretory rates of K+, NH4+ and inorganic phosphate between these two groups of birds. The excretory rates of Na+, Cl- and Ca2+ were significantly higher in saline-maintained birds than in the freshwater-maintained birds. NH4+ appeared to be a major cationic component which occupied over half of the available osmotic space in the urine of both the freshwater-maintained and saline-maintained birds. In saline-maintained birds the excretion of K+ and inorganic phosphate appeared to be independent of the available osmotic space in the urine whereas the excretion of Na+ and Cl- appeared to be very dependent upon this factor. These observations suggest that the kidneys of the saline-maintained bird constitute the primary pathway for the excretion of K+, NH4+ and inorganic phosphate, and that with respect to the excretion of Na+ they constitute a relatively minor pathway.
Quantitative Analysis of Swimmeret Beating in the Lobster
Authors: Davis W. J. 
Published: April 2021

ABSTRACT
High-speed motion pictures of the metachronous movements of the abdominal swimmerets of the lobster Homarus americanus were analysed. Measurements were made on films produced before and after removing part or all of individual swimmerets. Analysis of the intact swimmeret system provided quantitative constraints for models of the neural mechanisms underlying swimmeret beating. For example, the conduction velocity of the anterior-moving, metachronous wave increases with increasing frequency of swimmeret beating, as does the powerstroke amplitude and velocity of each swimmeret. The phase positions of individual swimmerets in the movement cycle are the same regardless of the frequency of swimmeret beating, and so are the ratios of powerstoke duration to returnstroke duration. The durations of the powerstroke, returnstroke and the short pauses between them decrease as the frequency of swimmeret beating increases. Removal of a swimmeret weakens the movements of ipsilateral swimmerets on adjacent segments, but does not affect the movements of contralateral swimmerets. Control experiments were performed to reduce the possibility that the effects were mechanical. The results suggest that proprioceptive feedback from the movements of individual swimmerets plays a supplemental role in the intersegmental coordination of the swimmerets of one side, but that contralateral proprioceptive influences are weak or absent.
The Mechanism of Burrowing of Some Naticid Gastropods in Comparison with That of Other Molluscs
Authors: Trueman E. R. 
Published: April 2021

ABSTRACTThe burrowing activity of naticid gastropods, described by use of ciné film and electronic recordings, shows four stages, together termed the digging cycle, which are repeated cyclically until burial is complete. In each cycle the retraction and extension of the propodium is integrated with the alternate swelling of two regions of the foot by the movement of blood within the pedal sinus. The shell is pulled into the sand with the propodium dilated by the fluid pressure generated by the columellar and intrinsic pedal muscles. The role of water in the expansion of the foot of Polinices is discussed. In a comparison of the burrowing process of naticids with that of other molluscs a general similarity is observed throughout the phylum and in other soft-bodied invertebrates. The major differences between the burrowing of gastropods and that of bivalves are discussed and indicate that in former burrowing is an adaption of normal surface locomotion, whereas the bivalves are more primitively adapted to an infaunal mode of life.
Effects of Eyestalk Removal On Rhythmic Locomotor Activity in Carcinus
Authors: Naylor E. , Williams Barbara G. 
Published: April 2021

ABSTRACT
Male Carcinus collected in summer and given several days to recover from eyestalk ablation showed a continuously high level of activity. Injection of eyestalk extract inhibited activity. Unlike control animals from which retinae were removed, experimental animals did not show a rhythm after chilling. Chilling the eyestalks alone elicited a rhythm similar to that appearing when the whole animal was chilled. The results are consistent with the view that locomotor rhythmicity is mediated via an inhibitory hormonal mechanism in the neurosecretory cell groups of the eyestalk. There is no direct evidence that the neuroendocrine mechanism alone constitutes an autonomous clock, however, and it is in any case probably co-ordinated by one or more other rhythmic systems within the crab.
The Genesis of Certain Cardiac Arrhythmias in Fish
Authors: Satchell G. H. 
Published: April 2021

ABSTRACT
The hearts of both elasmobranch and teleost fish are known at times to beat at a particular phase of the respiratory cycle and thus to exhibit a regular rhythm locked to that of respiration (Lyon, 1926; Lutz, 1930; Satchell, 1960; Shelton & Randall, 1962). In the laboratory, the hearts of Squalus acanthias and Mustelus antarcticus usually exhibit a 1:2,1:3 or 1:4 rhythm, the P wave of the electrocardiogram occurring as the mouth opens in the appropriate respiratory cycle. Lyon (1926) reported a 1:1 co-ordination in Carcharias sp. In Squalus acanthias it is known that respiration stimulates receptors in the pharynx, the afferent fibres of which pass up the branchial branches of the glossopharyngeal and vagus nerves to the medulla; the efferent limb of the reflex is the cardiac vagus nerve (Satchell, 1960).
Medium and Long-Term Changes in the Behaviour of Visual Neurones in the Tritocerebrum of Locusts
Authors: Horn G. , Fraser Rowell C. H. 
Published: April 2021

ABSTRACT
Extracellular recordings were made from single units in the tritocerebrum of locusts. The units responded to objects moved anywhere in the contralateral visual field. They were relatively insensitive to stationary stimuli and did not respond to auditory or tactile stimulation. Responses to successive movements gradually declined even when an interval of several minutes elapsed between each movement. The number of impulses evoked by a stimulus was strongly influenced by the amount and timing of previous stimulation. Such influences occasionally lasted for several hours. The responses of some cells to the first few groups of stimuli presented at the beginning of an experiment were non-decremental, but the response to subsequent stimulation was always decremental. Many of the units showed directional preferences, discharging more vigorously to movement in one direction than in the reverse direction. In no case was movement inhibitory to the cell. The directional preferences were modified by primacy so that for a number of presentations a unit responded preferentially to the directional characteristics of the first of a group of stimuli. The cells were insensitive to movement of the whole visual field brought about by movement of the whole animal, but still retained their responsiveness to relative movement within the visual field.
A Critical Study of the Evidence for Peripheral Inhibitory Axons in Insects
Authors: Usherwood P. N. R. 
Published: April 2021

ABSTRACT
The metathoracic anterior coxal adductor (a.c.a.) muscle of the locust and the grasshopper is innervated by a peripheral inhibitory axon similar to the inhibitory axon which innervates the metathoracic extensor tibiae muscles of these insects. No evidence was found to justify calling this axon an inhibitory-conditioning axon. Hyperpolarizing inhibitory postsynaptic potentials (IPSPs) are normally recorded from a.c.a. muscle fibres during stimulation of this axon, and if the bathing medium contains a high concentration of potassium ions the tonic fibres of the a.c.a. muscle relax slightly during inhibitory stimulation. The IPSPs are chloride potentials and can be converted to depolarizing responses by changing either the external or internal chloride concentration of the a.c.a. muscle fibres. Depolarizing IPSPs are frequently accompanied by small contractions of a.c.a. muscle fibres innervated by the inhibitory axon. The a.c.a. muscle fibres are permeable to potassium and chloride ions but influx of potassium chloride is much faster than efflux. Therefore when a.c.a. muscle fibres are loaded with chloride by exposing them to high-K saline (20−100 m-equiv. potassium/I.) and are then returned to normal (10 m-equiv. potassium/1.) saline the internal chloride concentration remains elevated for some time and during this period the equilibrium potential for the inhibitory response is less negative than the resting potential and the IPSPs are depolarizing. Depolarizing IPSPs are usually recorded from a.c.a. muscle fibres of locusts and grasshoppers when these fibres are transferred from their normal bathing medium, haemolymph, to 10 K saline. Probably the main reason for this reversal of the IPSPs is the entry of KC1 into the muscle fibres during dissection of the nerve-muscle preparations. Large quantities of KC1 would be released into the environment surrounding these preparations from muscle fibres cut and removed during dissection. Depolarizing IPSPs were more frequently recorded from muscle fibres of grassfed locusts than from fibres of starved locusts. The potassium concentration of haemolymph of grass fed locusts is higher than that of locust saline (10 m-equiv./l.). The potassium concentration of locust haemolymph presumably fluctuates in vivo but these fluctuations are too slow to affect the sign of the IPSP. The IPSPs are therefore always hyperpolarizing in vivo. The effect of changes in the potassium concentration of the bathing medium on the magnitude and polarity of the IPSP could account for the diverse responses recorded previously from a.c.a. muscle fibres of locusts and grasshoppers.
Control of the Circadian Rhythm of Activity in the Cockroach
Authors: Brady John 
Published: April 2021

ABSTRACT
A study was made of the concentration of potassium and sodium in the blood of Periplaneta americana to determine whether daily fluctuations occur which might imply ionic control of the circadian locomotor activity rhythm. Analyses were carried out on 166 blood samples taken at different times of day. A fall of about 10% occurred in the potassium concentration during the first hour of darkness; there was also a gradual decline of 2% in the sodium concentration. However, series of six successive blood samples taken over a period of 3 weeks from ten individual cockroaches revealed no daily change in the level of potassium, sodium or haemocyte density. No conclusions are drawn on the activity control aspect, but the results do suggest that daily changes may occur in cockroach blood ions.
Further Studies On Gradient-Dependent Diversification in the Pupal Cuticle of Galleria Mellonella
Authors: Stumpf Hildegard F. 
Published: April 2021

ABSTRACT
In last instar larvae pieces of integument from different regions of the sixth segment have been transplanted to the fourth segment. The formation by the grafts of a ridge (region 2) and of region-3 cuticle, normally occurring only in the fifth, sixth and seventh abdominal segments, has been studied in the pupa. Grafts containing presumptive regions 1, 2 and 3 developed these regions when transplanted to an equivalent position in the fourth segment. Grafts containing only presumptive region 1 formed also region-2 cuticle and region-3 cuticle when transplanted to the anterior part of the fourth segment. Grafts containing only presumptive region 3 formed also region-2 cuticle and region-1 cuticle when transplanted immediately posterior to the bristle B1 in the fourth segment. The results support the concentration-gradient concept. They reveal that the gradients in the fourth and the sixth segments are of the same nature and that the difference in the cuticular structure of these segments must result from a difference in competence. The concept of determination is discussed in relation to these results. Deceased, October 1967. See editor’s note, p. 59.
The Effect of Ultrasonic Irradiation On the Survival of Daphnia Magna
Authors: Wells P. N. T. 
Published: April 2021

ABSTRACT
Apparatus is described for the irradiation of Daphnia magna by 3 MHz. ultrasound, under controlled temperature conditions. The lethal level for heat exposure was established for Daphnia. It is shown that there was a threshold of irradiation level below which immediate death was due to heat. Above the threshold level for non-thermal damage, streaming in the environment of the animal became considerable. Long-term observations confirmed the existence of a threshold level for nonthermal damage during irradiation.
Thermoacclimatory Variations in the Haematology of the Common Carp, Cyprinus Carpio
Authors: Houston A. H. , Dewilde Mary Anne 
Published: April 2021

ABSTRACT
The haematology of winter, summer, and autumn populations of carp has been investigated as a function of acclimation temperature. Red-cell number, packed-cell volume, and haemoglobin tend to vary directly with temperature. Mean erythrocyte volume is increased at very low temperatures but, like mean erythrocytic haemoglobin and mean haemoglobin/unit erythrocytic volume, tends to be stable at moderate to high temperatures. Although the data suggest a temperature-correlated increase in blood oxygen capacity, it is apparent that the animals must invoke other forms of cardiovascular-respiratory adjustment as well. On a seasonal basis increases in oxygen capacity are seen at low, but not high, acclimation temperatures. It is suggested that this form of response may be related to the pattern of capacity acclimation typical of cyprinid fishes.
Motoneurone Discharges to the Eyecup Muscles of the Crab Carcinus
Authors: Burrows M. , Horridge G. A. 
Published: April 2021

ABSTRACT
During imposed tilt the eyecup of the crab tends to preserve an absolute position which depends upon the tonic activity of eight of the nine eyecup muscles. The detailed activity of all these muscles during imposed tilt in different planes has been recorded intracellularly. The slow- and fast-motoneurone discharges to the eyecup muscles differ in that the former have intervals which are more variable at lower frequencies but the latter are more variable at higher frequencies. The standard deviation of the interval between impulses is 20–30% of the mean interval for a wide range of frequencies of the tonic motoneurones. This large scatter is tolerable because the slow muscle fibres are sluggish and because the eyecup is also visually stabilized by a system of long time-constant. In roll the two eyecups move in opposite directions relative to the midline of the animal. In pitch the two eyecups move in the same direction relative to the body of the animal, but in neither case is there a correlation between individual impulses to the muscles of the right and left eyecups which are active at the same time. Possible mechanisms of linkage between the two eyecups are discussed.
The Onset of the Fast Phase in the Optokinetic Response of the Crab, Carcinus
Authors: Horridge G. A. , Burrows M. 
Published: April 2021

ABSTRACT
The onset of the fast phase in the optokinetic response is a part of a centrally determined programme. An eyecup moving in a slow phase toward the mid line governs the onset of the fast phase for both eyes and leads by 40−60 msec. Repeated reflex withdrawal of a governing eyecup suppresses the onset of the fast phase; similar stimulation of a governed eyecup has no effect on fast phases. After shocks applied near the governing eye the onset of the fast phase occurs earlier in the slow phase. Mechanical stimulation has the same effect. If the eyecup receives a shock whenever it moves too near the mid line in a slow forward phase, it soon changes the position of onset of the fast phase so that the shocks are avoided. The tonic motor frequency to muscle 21 at which the fast phase normally occurs is reduced. The effect is lasting. This plastic change is adaptive but is not learning; the earlier onset occurs irrespective of how or when the shocks are applied. The reinforcement need not supply any possibility of association. In a behaviour pattern which depends on a centrally determined programme of motor impulses for each stimulus situation the element of plasticity is one further component of the central pattern, so arranged that it is adaptive.
Development of A Computer Model Simulating Some Aspects of the Cardiovascular-Respiratory Dynamics of the Salmonid Fish
Authors: Taylor W. , Houston A. H. , Horgan J. D. 
Published: April 2021

ABSTRACT
A digital computer simulation depicting some features of cardiovascular-respiratory interaction in the salmonid fish has been developed. This embodies six controlled system relationships; three of which are mass balance equation describing oxygen transport and storage in the extra-branchial, branchial and general body phases. A Fick equation, and two relationships approximating the transport characteristics of venous and arterial blood are also included in the system equations. Three feedback equations provide for adjustments in cardiac output, ventilation and exchange surface area. The model predicts, with reasonable accuracy, values for ventilation, cardiac output and blood gas tensions under conditions of routine and moderate activity in an oxygen-sufficient environment. Qualitative agreement between predicted and experimental values has been obtained in simulations of responses to progressive environmental hypoxia. The study emphasizes the probable role of venous oxygen tension in the regulation of ventilatory and cardiac activity. A central role for branchiovascular responses in adaptation to elevated oxygen demand is also indicated. The existence of a depressor function, operating under conditions of acute hypoxia to dampen positive ventilatory feedback effects is suggested by simulation of responses to reduced environmental oxygen tensions.
Motor Performances of Some Cephalopods
Authors: Trueman E. R. , Packard A. 
Published: April 2021

ABSTRACT
It has long been recognized that contraction of the mantle muscles of a pelagic cephalopod produces high hydrostatic pressure in the mantle cavity, a jet of water from the funnel and movement of the animal in the opposite direction (Fig. 1). As a result of their investigation of the responses of squid muscle to repetitive stimulation of giant nerve fibres, Prosser & Young (1937) considered that the expulsion of each jet of water, occurring in locomotion, is a single unitary act which is performed in an all-or-nothing manner. Absence of any increased response in fresh muscle preparations at higher frequencies showed that a single nerve impulse carried by a giant axon is capable of activating every muscle fibre that it reaches. In parallel with the decapod fast system there is a slow system made up of many small-diameter nerve fibres, which when stimulated provoke smaller graded muscular contractions in a mantle preparation (Young, 1938). This author assumed that these graded contractions produced the mantle movements involved in respiration. The graded contractions were further studied by Wilson (1960) who demonstrated that Octopus (O. bimaculatus and 0. bimaculoides) also have a fast and a slow system. The fast system of Octopus, unlike that of the decapods, shows marked facilitation of the mechanical response and a single: twitch takes 160 m.sec. to reach maximum tension. Summation of Octopus fast and slow systems and of the squid slow response take place in a two-phase manner, a rapid increase in tension being followed by a slower rise.
On Respiration in the Dragonet Callionymus Lyra L
Authors: Hughes G. M. , Umezawa Shun-Ichi 
Published: April 2021

ABSTRACT
The usefulness of a bottom-living fish, the dragonet (Callionymus lyra), in experiments on fish respiration is described. The position and nature of its opercular opening made it possible to determine directly the volume of water pumped over the gills and the of the mixed expired water. The normal ventilation volume for a 100 g. fish was about 30 c.c./min. The relationship between cardiac and respiratory rhythms was investigated and showed a variety of ratios. The heart usually beats more than once during each respiratory cycle. Individual variations in the coupling between these rhythms was common and close couplings were observed in the absence of anaesthetic and at normal . Changes in minute volume produced by altering the hydrostatic pressure across the respiratory system did not affect the heart rate. Percentage utilization fell at higher flow rates. Changes in flow per cm. of water pressure gradient was less with negative gradients than when the static pressure on the mouth side exceeded that in the opercular collecting chamber. Oxygen consumption of the fish is directly related to the ambient over a wide range (30-120 mm. Hg). Sudden lowering of the in the inspired water leads to compensatory responses in which the minute volume is maintained or increased as a result of a rise in stroke volume and lowered respiratory frequency: there is also a marked bradycardia. During recovery the increased oxygen consumption of the fish resulted from a rise in utilization rather than a change in the respiratory rate or ventilation volume. Analysis of the time course of the changes in heart rate and ventilation volume in experiments in which was changed supports the view that the receptors mediating bradycardia occur on the gills and respond directly to the change in rather than to the secondary increase in flow produced by the hypoxia.