bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Shape Discrimination in Octopus After Removal of the Vertical Lobe
Authors: Muntz W. R. A. , Sutherland N. S. , Young J. Z. 
Published: April 2021

ABSTRACT
In all previous investigations of the effects of vertical lobe removal on the discrimination of shape by Octopus, the animals were trained with the shapes presented successively, i.e. they were trained to attack one shape (the positive) when presented on its own, and not to attack another (the negative) when presented alone. Under these conditions, animals lacking the vertical lobes can learn to perform above chance with easy visual discriminations, but post-operative performance is much poorer than in unoperated controls whether animals are trained before or after the operation (refs, in Young, 1961). Animals are very severely impaired on a difficult discrimination, and may indeed give no evidence of learning. Some findings suggest that the poor performance is partly due to fluctuations in the tendency to attack that result from removal of the vertical lobes; thus operated animals tend to take any shape shown immediately after having been fed (whether it is positive or negative) and tend not to take any shape shown after receiving a shock.
Preparation for Flight by Hawk-Moths
Authors: Dorsett D. A. 
Published: April 2021

ABSTRACT
Moths belonging to the family Sphingidae are not capable of controlled flight until the temperature of the flight muscle has been raised by a preliminary period of vibrating the wings. The flight-temperature of forty-five specimens of Deilephila nerii varied between 34 and 45° C., but individuals always flew at the same temperature. The temperature inside the thorax rose at a mean rate of 4·2° C./min. Alteration of the ambient temperature affects the duration of the warming period but not the flight-temperature. The flight-temperature shows a positive correlation with the wing loading. In Deilephila and two other genera of similar dimensions, an increase of 50 mg. in the wing loading corresponds to a rise of 5 ·75 ° C. in the flight-temperature. A method of measuring the rise in wing-beat frequency during the warming period is described. The thoracic temperature increases linearly with the frequency. It is concluded that the frequency of the wing beat is determined principally by the wing loading, whilst variations in the other parameters of the wing stroke provide the ‘fine control’ of flight regulation required during flight and whilst hovering.
Olfactory Stimuli and Oviposition in the Blowfly, Phormia Regina Meigen
Authors: Wallis D. I. 
Published: April 2021

ABSTRACT
The work described attempts to elucidate the sensory mechanisms involved in the act of oviposition. A brief account of the morphology of the ovipositor and the distribution of the various sensilla on it is given. Behavioural experiments have shown unequivocally that receptors on the anal leaflets of the ovipositor are olfactory and can mediate oviposition. Flies are able to discriminate when antennal, palp and labellar receptors are blocked, but not when the ovipositor pegs are waxed over as well. A method for waxing the latter is described. Sensilla on the antennae, labellum and ovipositor perceive the olfactory stimuli which are important in inducing oviposition. Possibly there are olfactory receptors at other sites which mediate other types of behaviour. Tactile stimuli perceived mainly through sensilla on the ovipositor can play an important role in egg distribution and a minor role, possibly, in inducing oviposition. All the evidence suggests the pegs are the olfactory receptors on the ovipositor which mediate oviposition. A summary of factors known or suspected to influence oviposition is given.
On The Nervous Control of the Velar Cilia of the Nudibranch Veliger
Authors: Carter G. S. 
Published: April 2021

ABSTRACT(1) The beat of the velar cilia of the Nudibranch veliger is intermittent and appears to be under the control of the organism. (2) Fibres lying between the cells which bear the velar cilia are described. They end near the outer surface of these cells in fibrils which resemble those of the muscle-plate in structure. They stain with specific nerve-stains and were shown to be in all probability continuous with nerves lying deeper in the tissues. It is concluded that these are nerve-fibrils. (3) Within the ciliated cell at the level of the terminal fibrils of these fibres there is a layer of granules which stain with methylene blue. (4) The cilia of cells which have been separated from the tissues beat actively but the beat is continuous and not intermittent. (5) In the presence of various narcotics the intermissions are inhibited more quickly than the beat of the cilia is affected and at a lower concentration of the drug. (6) Some drugs which are not known to act as narcotics were used and with certain exceptions, which are discussed, did not have this effect. (7) In an acid medium the beat is slower but the intermissions continue so long as the cilia beat. (8) In an alkaline medium the intermissions are inhibited before the beat is affected. This is discussed and it is suggested that it is in accordance with recent work on the effect of changes in the reaction of the medium on nerve-tissue. (9) It is concluded that the nerve-endings found among these cells are regulatory and are concerned in the causation of the intermissions. The beat of the cilia is therefore under the control of the nervous system of the animal.
The Hydrogen-Ion Concentration of Natural Waters, I. the Relation OfpH To The Pressure Of Carbon Dioxide
Authors: Saunders J. T. 
Published: April 2021

ABSTRACTThe evidence that the variations which occur in the hydrogen-ion concentration of a natural water have any direct effect on the inhabitants living under natural conditions is scanty and not very convincing. On the other hand, there is good evidence to show that many animals are tolerant of the changes in hydrogen-ion concentration of their native habitat. These variations can hardly be related to distribution, epidemics of conjugation and the like, for these are known to occur at very different values of the hydrogen-ion concentration. Occasionally it can be shown that the variations are sufficiently extreme to cause the total extinction of certain species, but this will only be in very small pools. It is true, of course, that profound changes can be produced in biological reactions in the laboratory by altering the hydrogen-ion concentration of the medium in which the reaction is taking place, but these changes are nearly always greatly in excess of the natural changes occurring in the normal environment. It appears to me that the real importance of the measurement of the hydrogen-ion concentration of a natural water is that it can be used as an accurate measure of the carbon dioxide produced by the animals and of the photosynthetic activity of the plants. But to use the measure of the hydrogen-ion for this purpose we must know something of the underlying principles involved in the measurement and must not merely be content with matching the colour produced by the addition of an indicator with the colour of a buffer solution prepared by a rule of thumb method.
The Energy-Sources in Ontogenesis
Authors: Needham Joseph 
Published: April 2021

ABSTRACT
Investigation of the ammonia content of the developing hen’s egg shows that though in absolute amount it steadily increases during incubation, in percentage of the embryonic weight it declines. The intensity of production of ammonia reaches its highest point on the fourth day, i.e. five days before that of urea production, and seven days before that of the production of uric acid. The absolute amounts of nitrogen excreted in the form of ammonia are so small, however, that the curve for protein combusted by 100 gm. of embryo each day is hardly affected, and rises to a peak between the eighth and ninth days. These results are compared with others already in the literature of chemical embryology, which seem to bear on the theory of recapitulation. They afford further support to the conception of an ontogenetic succession of energy-sources.
The Vitality of the Spermatozoa in the Male and Female Reproductive Tracts
Authors: Hammond John , Asdell S. A. 
Published: April 2021

ABSTRACT
Methods and experiments are described for testing the length of fertility of the sperms in the male and female tracts of rabbits. The sperms may retain their fertility in the male tract up to 38 days, but in the female tract only up to 30 hours. In cases where the sperms had remained in the female tract for 24-30 hours before ovulation small litters were frequently produced; it is suggested that this is due to the end point of the vitality of the sperms falling within the limits of time during which the process of ovulation occurs. The bearing of these results on problems of fertility and sterility is discussed.
Temperature and Time of Development of the Two Sexes in Drosophila
Authors: Bonnier Gert 
Published: April 2021

ABSTRACT
The time of development at 25° C. up to the moment of pupation is found to be for females and males respectively 116·62 ± 0·19 and 116·78 ± 0·20 hours. During the pupal stage the two times are 111·36±0·15 and 115·46 ±0·13 hours. At 30° C. the corresponding figures are (in the same order): 99·95 ± 0·49, 103·37 ± 0·43, 78·15 ± 0·50 and 84·26 ± 0·34 hours. These figures show that there is a statistical significance in the differences of the times of development of the two sexes for both the periods at 30° C. but only for the pupal stage at 25° C. It is pointed out that the fact that the longer time of male development as compared with female development at 25° C. is confined to the pupal stage, may be correlated with the other fact that the essential parts of the secondary sexual characters are developed during this stage. It is shown that there is a negative correlation between the pre-pupal and pupal times of development, indicating that the longer the first time is, the shorter is, as a rule, the other time and “vice versa. With the aid of statistical methods it is shown that the shortening of the time of development at 30° C. as compared with the time at 25° C. is much more pronounced for the pupal than for the pre-pupal stage. This last fact is discussed and it is emphasised that the ordinary methods of studying the influence of temperature on development are too rough to be of more than of a descriptive value, the only way of getting a deeper insight into the processes of development by temperature studies being the separate studies of a number of short intervals.
The Growth of Fish
Authors: Gray J. 
Published: April 2021

ABSTRACT
In most studies of post-embryonic growth it is customary to accept the observed increment in the total mass of the organism per unit time as an index of growth. Davenport (1897) found, however, that the opening phases of development of the frog were characterised by a very rapid rise in the water content of the embryo whilst the dry weight during this period gradually decreased. He concluded from these facts that the process of early embryonic growth was of a different and more “passive” nature than the more “active” growth which later ensues. Passive growth was regarded by him and by others as some form of imbibition, whilst the subsequent “active” growth involved the conversion of organic substances into living tissue and so involved an increase in dry weight. In the case of terrestrial animals, however, it has been known for some time that with increasing age the percentage of water in the organism falls, and the recent figures of Murray (1926) show that this fall is detectable at a very early age. It must be remembered that Davenport’s figures apply to the whole larva which in its early stages is heavily charged with yolk, whereas Murray’s figures apply to the embryo alone.
Uterine Grafts
Authors: Hammond John 
Published: April 2021

ABSTRACTFoetal tissues were transplanted into the pseudo-pregnant uterus of the rabbit, a suitable position for such grafts owing to the raised nutrition of the uterus occurring in the early stages of pseudo-pregnancy. Several tissues particularly large amounts of cartilage and small quantities of epithelial tissue persisted and grew, the former undergoing ossification. The growth of these foetal tissues in the pseudo-pregnant uterus did not cause the corpus luteum of pseudo-pregnancy to persist or the mammary gland to thicken as in pregnancy. Since—(a) the foetal tissues only grew where they were attached to the muscle layer of the uterus, although every effort was made to attach them to the mucosa; (b) the parts of the grafts lying in connection with the mucosa were absorbed rather than nourished; and (c) the introduction of living foetal tissue failed to cause any further development of the deciduomata which were produced by cutting the pseudo-pregnant mucosa—it is suggested that normally the attachment of the foetus is caused by the active erosive (digestive) agency of the foetal trophoblast, a function which is absent in the cells of the foetus itself. It seems probable that just as the small deciduomata are formed as a response to a cut so the large maternal placenta is formed as a response to the continuous erosion by the foetal trophoblast.
A Note on Haemerythrin
Authors: Marrian Guy Frederic 
Published: April 2021

ABSTRACTThe effect of change of temperature on the dissociation curve of oxyhaemerythrin is shown. The heat of combination between haemerythrin and oxygen has been calculated to be 10,350 calories per gramme molecule of oxygen. It has been shown that oxyhaemerythrin is only stable over a small range of pH. The pigment appears to be most stable at pH 8·0 and 9·0. Variation of hydrogen-ion concentration between pH 6·0 and pH 10·0 appears to have little effect on the dissociation curve of oxyhaemerythrin. Oxyhaemerythrin can be converted to a yellow “methaemerythrin” by the action of oxidising agents. The change occurs spontaneously at slightly acid hydrogen-ion concentrations. Attempts to show the presence of haem in the haemerythrin molecule have been unsuccessful. The nature of the purple colour produced by the action of concentrated H2SO4 on a solution of oxyhaemerythrin is discussed. Photographs of the absorption spectra of oxyhaemerythrin, methaemerythrin and the H2SO4 product of oxyhaemerythrin are shown.
The Relation OfSpirostomum AmbiguumTo The Hydrogen ION Concentration (Alkaline Range)
Authors: Jenkin Penelope M. 
Published: April 2021

ABSTRACTA recovery method is described for determining the survival time of Spirostomum ambiguum (Ehrenberg) major in solutions of different hydrogen ion concentration. The survival time is defined as the longest time for which the animals can remain in the solution of harmful hydrogen ion concentration and afterwards recover their normal appearance when transferred back to a solution, the hydrogen ion concentration of which is known to be harmless. The results are given of experiments carried out in two solutions both of which provided media of known hydrogen ion concentration, but allowed this factor to be controlled by entirely different substances. The solutions were : Palitzsch’s borax-boric acid buffer mixture diluted ten times with glass distilled water. Cambridge tap-water (-0042 N carbonates) containing regulated amounts of carbon dioxide in solution. These experiments showed that the hydrogen ion concentration was a very important factor in determining the survival time of Spirostomum in the medium. In media of pH 7·4 the Spirostomum survive indefinitely but in solutions of pH 9·4 they rapidly die after greater or less swelling, according to the osmotic pressure of the medium. The time of survival decreases with increasing alkalinity and between pH 9·0 and 7·6 it is inversely proportional to the hydrogen ion concentration. Between pH 7·6 and 7·4 the time of survival is not proportional to the hydrogen ion concentration and a very slight decrease in the hydrogen ion concentration at this point will cause a very considerable, and quite disproportionate, decrease in the time of survival. It is suggested that such a slight decrease in the hydrogen ion concentration of the water is the possible explanation of the very sudden disappearance of Spirostomum from ponds, where it was existing in very large numbers.The destruction of the Spirostomum in media of greater alkalinity than pH 7.4 is probably due to the increase in alkalinity affecting the body wall in such a way that it becomes more permeable to water, the result, as observed, being that the animals swell up and eventually burst.
Humidity Reactions of Three Aquatic Amphipods, Gammarus Duebeni, G. Oceanicus and Pontoporeia Affinis in the Air
Authors: Lagerspetz Kari 
Published: April 2021

ABSTRACT
It has been previously shown that the aquatic isopod Asellus aquaticus—when taken out of water—is able to select the higher of two different humidities of the air (Lagerspetz & Lehtonen, 1961). In that connexion, it was suggested that some aquatic amphipods, when exposed to air, would probably also exhibit behavioural reactions to differences in atmospheric humidities.
The Effect of Temperature on Locust Flight Muscle
Authors: Neville A. C. , Weis-Fogh Torkel 
Published: April 2021

ABSTRACT
In a recent study of the motor activity in relation to the wing movements of flying desert locusts, muscle action potentials were used to indicate mechanical activity of single motor units and also to demonstrate the motor repertoire of the central nervous system at the unit level (Wilson & Weis-Fogh, 1962). In order to do this it was essential to know exactly how the recorded potentials are related to the mechanical response at the relatively high thoracic temperature of flying locusts, 30–42° C. ; this information is provided here. During flight at medium intensity most muscles are fired a single time per stroke cycle and the movements are based upon ordinary twitch activity, but in some control reactions and during more powerful flight, D. M. Wilson discovered that locusts often make use of double firing, i.e. a unit is fired by two closely spaced action potentials (in the locust normally 4–8 msec.). In cases where the tetanus : twitch ratio is higher than unity this can obviously result in more force and power and he suggested that this may provide an important control mechanism in such systems which operate essentially on a twitch basis (Wilson, 1960). It was therefore of interest to investigate the mechanical effect of double firing.
The Relation Between Stimulus Parameters and Current Flow Through Stimulating Electrodes
Authors: Rowell C. H. Fraser 
Published: April 2021

ABSTRACT
The flow of current through a small metal electrode, such as is commonly used in stimulation experiments, has been studied. The wave-form resulting from rectangular voltage pulses has been examined with various electrodes, preparation impedances and analogue networks. Variation of pulse repetition rate, when all other parameters are constant, causes wide variation of current flow and lesser variation of wave-form. An attempt has been made to relate these changes to physical changes occurring at the electrode tip during polarization of the electrodes. Calculations indicate that the amount of gas generated by the currents commonly used in stimulation experiments would produce gross distortion of the tissues in the absence of diffusion, and may do so in practice when large currents are used. It is concluded that changes of threshold with changes of pulse repetition rate are as likely to be due to the physical effects described here as to the physiological characteristics of the stimulated nervous system, to which they have sometimes been ascribed.
Some Factors in the Activation of Crab Movement Receptors
Authors: Mendelson Martin 
Published: April 2021

ABSTRACT
The activation of movement receptors in Pachygrapsus crassipes is examined. Lengthening and shortening of the elastic strand of the propodite-dactylopodite (PD) organ are respectively the adequate stimuli for movement receptors responding uniquely either to closing or opening. These stimuli are also effective on the isolated PD organ. Twisting of the strand is without effect. Intracellular records from the receptor cells show apparent intermittent generator potentials during effective stimulation. No electrical activity is observed at subthreshold speeds or during movement in the inappropriate direction. The action potentials are initiated in the distal process at a considerable distance from the soma. Nicotine applied to the PD organ in high concentration elicits spike discharges of high frequency and long duration; it has no effect when applied to the axons. Applied to the PD organ in low concentration it potentiates the effect of mechanical stimulation without itself eliciting spikes. These findings are discussed in relation to the structure of the receptor endings and a mechanism is tentatively suggested to account for the unidirectional sensitivity.
The Filter-Feeding of Artemia
Authors: Reeve M. R. 
Published: April 2021

ABSTRACT
The rates of filtration and of ingestion have been studied in Artemia of different ages feeding on pure cultures of plant cells of three different species, the concentrations of cells being varied over two orders of magnitude. The animal is capable of regulating its rate of feeding in such a way that, as the cell concentration increases, the filtration rate maintains a constant maximum value while the ingestion rate increases. When the concentration reaches a value at which a constant maximum ingestion rate is attained, the filtration rate falls off. In older animals the maximum ingestion rate is reached at a lower cell concentration than in younger animals. The maximum filtration rate is independent of cell size. The maximum ingestion rate is inversely related to cell size, the total volume of cells ingested being the same for three species of plant cells. The means whereby the animal maintains a maximum rate of total volume of cells ingested per unit time, irrespective of their size, has been investigated and is discussed.
Negative Pressures Produced in the Pharyngeal Pump of the Blood-Sucking Bug, Rhodnius Prolixus
Authors: Bennet-Clark H. C. 
Published: April 2021

ABSTRACT
The sucking pump of Rhodnius drives blood from the host into the abdomen at a rate of up to 20 mm.3/min. The stylet canal is 8–10 μ diameter at the apex and the rate of taper is not more than 1 μ increase in diameter/100 μ length. The pressure required to force water through such a tube at that rate is about 2 atmospheres. The pressure required with blood would be higher. The musculature of the pump is theoretically capable of exerting a force on the pump piston of at least 2·5 atmospheres, while contracting at the required speed. The bug is capable of feeding at near to the normal rate when the surrounding pressure is 0·2 atmospheres and also against a pressure gradient of 0·2 atmospheres. The retreating contact angle of insect cuticle to a blood-air interface is very low. It is suggested that the high tensile strength of the blood and the low contact angle of the pump walls to the blood are the reasons why cavitation does not occur in the feeding pump of Rhodnius when the internal pressure drops below the vapour pressure of blood.