bluuebunny/crossref_metadata_2025_split huggingface dataset:
Training, Speed and Stamina in Trout
Authors: Bainbridge Richard 
Published: April 2021

ABSTRACT
A number of trout (Salmo irideus) were kept continuously swimming for a period of 12 months in experimental tanks in which the water was made to rotate at a mean speed of 25 cm./sec. These fish become available for study in the ‘Fish Wheel’ and measurements were made of the maximum speed they sustained for periods of swimming of different duration. For bursts of swimming of up to 20 sec. duration the mean accomplishments of these fish were identical with those of the unexercised trout studied previously. Considerable variability was found amongst the specimens tested and the best of the present exercised fish were appreciably better than the best of the previous unexercised ones. The biggest improvement was 36% at the 10 sec. period of swimming; the mean percentage improvement for all periods was 11%. Some specimens were found better at swimming for short periods and others at swimming for longer. In the absence of comparable figures for the earlier fish, the measurements of cruising speeds sustained for periods up to hr. were compared with other figures in the literature and found to be about half some of these for wild fish. The implications of the results are considered and two interpretations stressed. First, it is assumed that there is a real identity of accomplishment for short periods of swimming, values being determined perhaps solely by gross mass of muscle; while for longer periods of swimming differences dependent upon respiratory rate etc. may well occur. Secondly, for such longer periods the discrepancies reported here may well be accounted for by differing degrees of stimulus and behavioural response under varied experimental conditions.
Olfactory and Visual Learning in the Red-Eared Terrapin, Pseudemys Scripta Elegans (Wied.)
Authors: Boycott B. B. , Guillery R. W. 
Published: April 2021

ABSTRACT
Terrapins have been trained to olfactory and visual stimuli. The animals are able to discriminate meat alone from meat with amyl acetate, vanillin, eucalyptus or a black figure. The olfactory discrimination is learned less readily than the visual discrimination under comparable conditions. Destruction of the olfactory nerves shows that amyl acetate and vanillin are olfactory stimuli. The discrimination to amyl acetate is lost for about 6 weeks after destruction of more than half of the olfactory nerves, and the postoperative feeding behaviour is temporarily altered. Olfactory lesions do not disturb the discrimination or feeding behaviour of animals trained to a visual situation. Animals with large olfactory lesions show recovery of the amyl acetate discrimination after 6 and more weeks of postoperative training. It remains to be determined whether the recovery is due to a taste or general chemical discrimination or to surviving olfactory fibres. The method should prove suitable for studying the olfactory and perhaps other functions of the chelonian forebrain.
Temperature Acclimation and the Nervous System in Fish
Authors: Roots Betty I. , Prosser C. Ladd 
Published: April 2021

ABSTRACT
The cold-blocking temperature of a simple reflex in goldfish (Carassius auratus) and bluegills (Lepomis macrochirus) was 10,° 5° and 1° C. respectively for fish acclimated to 35°, 25°, and 15° C. The response of 5° C. fish was not blocked at 1° C. Similar results were obtained with goldfish in which the spinal cord had been cut immediately posterior to the medulla. Conditioned inhibition of respiration in goldfish acclimatized to 30°, 25°, 15° and 5° C. was blocked at 20°, 15°, 10° and 1° C. respectively. A conditioned avoidance response of goldfish acclimated to 25° C. was blocked at 15° C. The cruising speed of green sunfish (Lepomis cyanellus) is related to the ambient temperature, and the upper and lower temperatures at which they do not swim are related to their thermal history. Peripheral nerves of bluegills and green sunfish acclimated to 25° C. continued to conduct impulses at temperatures below 5° C. It is concluded that the site of cold-block is in the central nervous system.
Structural Changes in the Suprarenal Gland of the Mouse During Pregnancy
Authors: Tamura Y. 
Published: April 2021

ABSTRACT
In the mouse there is no correlation between body weight, body length, and the size of the suprarenal gland. The size of this gland is not always indicative of its functional activity. Unilateral ovariotomy has no effect on the functional activity of the suprarenal gland. During pregnancy the gland becomes reduced in area. The hypertrophy of the zona glomerulosa occurs during pregnancy and at the 17 mm. stage it reaches the maximal secretory activity. Observations on the hypertrophy of the zona fasciculata are in agreement with those of other workers. This hypertrophy may be caused by either an enlargement of cells or an increase of their number. In the latter case it is due to the appearance of a new zone, zona gestationis. This zone reaches its maximal activity at about 17 mm., and at this stage so-called siderophile bodies (secretory granules) are visible in great numbers. Zona reticularis degenerates rapidly at an early period (before formation of placenta) of pregnancy, and at the middle of pregnancy the site of this zone is occupied by vacuoles. The hypertrophy of the medulla occurs at the closing period of pregnancy. Mitotic figures were observed in every zone except zona reticularis at an early period of pregnancy. The secretory activity of this gland increases slowly and reaches its maximum at about the third quarter of pregnancy, followed by a partial decrease during the last quarter.
Studies on the Sex-Ratio and Related Phenomena
Authors: Parkes A. S. 
Published: April 2021

ABSTRACT1872 normal mice bred during November 1922-October 1925 had an average litter-size of 6·18, and a male percentage of 51·7 ± ·77, both of which figures are lower than the corresponding ones found for 1921–2. The annual variation in the sex-ratio is, however, not very appreciable, the figures for the four years running 54·2 ± 1·04, 50·4 ± 3·22,52·2 ± I-18, 51·4 ± 1·09. The average size of litter during these four periods ranged from 6·65 to 5·93. Considerable seasonal variation in both fertility and sex-ratio occurred, the highest figures being fertility 6·46 and male percentage 55·9 ± 1·83 in the October-December quarter, and the lowest being fertility 5·82 and male percentage 48·2 ± 1·46 in the April-June period. Litter-size appeared to be uncorrelated with any sort of definite variation in the sex-ratio. Recent work on the mouse is discussed.
The Relation of Combined Nitrogen to the Physiological Activity of Azotobacter
Authors: Zoond Alexander 
Published: April 2021

ABSTRACT
Increasing concentrations of nitrate, amino acid and peptone decreased proportionally the amount of atmospheric nitrogen fixed in culture solutions oi Azotobacter. Increasing concentrations of sterile, unheated, plant extracts increased the amount of atmospheric nitrogen fixed up to a maximum limit, after which the fixation gradually decreased with further additions. The addition of sterile, unheated plant extracts to pure solution cultures greatly stimulated the multiplication of Azotobacter. Very heavy applications of plant material to soil effectively checked the assimilation of nitrogen, and at the same time greatly increased the concentration of nitrogen in the soil solution. It is suggested that Azotobacter always prefers to derive its nitrogen from a combined source but that plant tissues contain certain unknown “essential food substances” which stimulate the growth of the organism to such an extent that the supply of available nitrogen derived from moderate applications of vegetable material is soon exhausted, and the organism then assimilates nitrogen from the air.
A Chemical Study of the Manoilov Test for the Differentiation of the Sexes
Authors: Falk K. George , Lorberblatt I. 
Published: April 2021

ABSTRACTThe chemical differentiation between the sexes of substances derived from various animal and plant products, which is shown by the Manoilov reaction, has aroused considerable interest. An attempt to throw light on the chemical changes involved in this reaction, together with a simplification of the test, will be described in this paper. The test as described by Manoilov (1) consists essentially of successive additions to an aqueous or 60 per cent, alcoholic extract of the substance in question of a definite number of drops of solutions of the following substances : papain, dahlia (or methyl green), potassium permanganate, hydrochloric acid, and thiosinamine. If the test is successfully carried out, the preparation from the female gives a pink to red or violet solution, while that from the male remains colourless. The directions for carrying out the tests include definite pauses after the addition of some of the reagents, and precautions against agitating the mixtures until after the addition of the first four.
Lactic Acid in Fish and Crustacean Muscle
Authors: Ritchie A. D. 
Published: April 2021

ABSTRACTLactic acid is produced in the muscles of several species of fish examined and of lobsters under conditions in which it is known to be produced in other animals already studied. The quantity present is less than in the skeletal muscles of the land-living vertebrates. The highest concentration found (in haddock) is comparable to that found in mammalian heart muscle ; the lowest (in hake) is comparable to that found in reptilian smooth muscle. There is a remarkable difference between these two fish of the same family; greater than any difference observed between the skeletal muscles of land-living vertebrates.
Experiments on Artificial Cryptorchidism and Ligature of the Vas Deferens in Mammals
Authors: Cunningham J. T. 
Published: April 2021

ABSTRACTIt has long been known that as a rule the abdominal or undescended testis in man and other Mammals is sterile, and that normal and complete spermatogenesis does not occur in it. Dr F. A. E. Crew (2) suggested in 1922 that the cause of this infertility was the higher temperature of the abdominal cavity compared with that of the scrotal cavity. Mr Carl R. Moore ((5) 1922) of the Hull Zoological Laboratories, University of Chicago, made the same suggestion in the same year and has since published evidence in support of it (Moore, C. R.(6) 1924). He has shown that experimental cryptorchidism produces a condition of the testis essentially similar to natural cryptorchidism. The testis may be made to remain in the body cavity in Rodents, which have a wide and open inguinal canal, by separating the testis from the scrotal wall, pushing it into the abdomen, and closing the inguinal canal with a purse-string suture; by fastening the caput epididymis to the abdominal wall with a suture; or by everting the scrotal sac into the abdomen and securing its walls to the body-wall. In the adult guinea-pig 7 days’ retention was sufficient to produce degeneration of the various cells in the different stages of spermatogenesis.
Chemotaxis of Rabbit Spermatozoa
Authors: Dickmann Z. 
Published: April 2021

ABSTRACT
The aim of the study was to determine whether rabbit eggs’attract’ homologous spermatozoa in vivo.
Preliminary experiments showed that, in vitro, rabbit spermatozoa readily and irreversibly attach to the zonae of rat eggs.
When rat and rabbit eggs were transferred into oviducts of previously mated rabbits, a significantly larger number of spermatozoa collected within the rabbit eggs than on the zonae of the rat eggs. Since the experiments were designed so that rat and rabbit eggs had equal chances of sustaining collisions with rabbit spermatozoa, the great preponderance of spermatozoa in the rabbit eggs suggests that the latter exert a chemotactic influence on rabbit spermatozoa.
Motor Unit Distribution of the Dorsal Longitudinal Flight Muscles In Locusts
Authors: Neville A. C. 
Published: April 2021

ABSTRACT
The peripheral pathways of the ‘fast’ motor fibres to the locust dorsal longitudinal flight muscles are described at the single unit level, from electrophysiological and histological studies. This is summarized in a diagram on Pl. 1. Both pterothoracic dorsal longitudinal muscles consist of five anatomically distinct motor units, arranged in layers from dorsal to ventral. Each of the four more ventral units of both muscles receives a motor axon from the segment in front via the recurrent nerve, whereas the uppermost motor unit is innervated in each case from the segment containing the muscle. The motor units are nearly equal both in size and capability for work. Each of the five ‘fast’ motor axons innervates one topographically distinct bundle of muscle fibres. There is no overlap between muscle motor units. Even within a single muscle, motor units are capable of vibrating at independent frequencies. This indicates that the coupling of units which occurs during flight is neither structurally nor functionally rigid. With respect to peripheral features, the motor units within each dorsal longitudinal muscle are designed for fast response which improves the synchronization when the relevant neurons fire simultaneously (large motor axons, 15–25 μ in average diameter with high propagation velocity, 8 m./sec. at flight temperature). It is suggested that a tonic motor output, containing at least three units, which was recorded from mesothoracic nerve IBa, travels to the small lateral dorsal muscles.
Electrical Responses from Dually Innervated Tactile Receptors on the Thorax of the Crayfish
Authors: Mellon Deforest 
Published: April 2021

ABSTRACT
Electrophysiological recordings have been obtained from tactile receptors which occur in shallow pits on the crayfish carapace. Controlled mechanical stimulation has established that each receptor is innervated by a pair of sensory neurons. One of these neurons responds when the receptor is moved anteriorly, and the partner cell responds to displacement in the opposite direction. The receptors are sensitive to motion of the fluid medium in which they are immersed, and they may provide the animal with a means for determining the speed and direction of water currents. Vital staining procedures have confirmed the presence of two bipolar sensory cells associated with each receptor. An abrupt increase in the diameter of the sensory axons occurs several hundred microns proximal to the cell bodies of the neurons, and it is suggested that this is the locus of spike initiation.
Movement of the Flagella of Polytoma Uvella
Authors: Brokaw C. J. 
Published: April 2021

ABSTRACT
Dark-field photographic records of the wave patterns of moving flagella have been made using multiple-flash exposures at flash rates of up to 50 per sec. Patterns obtained from ATP-reactivated isolated flagella show reduced amplitude of bending, but are otherwise similar to those obtained from flagella under normal conditions. The co-ordination required to produce propagated waves of active bending appears to be preserved after isolation and reactivation. Addition of methyl cellulose to the medium to increase the viscosity reduces the frequency of beat much more than the amplitude. This behaviour can be partially explained by an analysis of the equations for sinusoidal wave movement of flagella which shows that maximum efficiency of forward swimming will be obtained if the amplitude of beat is maintained greater than times the wavelength, and variations in available power or viscosity are compensated by changes in beat frequency. Wave patterns at low frequencies in low ATP concentrations are unlike those obtained when the frequency is reduced by increased viscosity. The effect of ATP concentration on beat frequency is not explained by an effect on the power available for beating or by an effect on the ‘internal viscosity’ of the flagella.
A Stretch Reflex Controlling Wingbeat Frequency in Grasshoppers
Authors: Wilson Donald Melvin , Gettrup Erik 
Published: April 2021

ABSTRACT
The stretch receptors of the wing hinge of the locust Schistocerca fire once or twice at the top of the wingstroke during normal flight. Removal of the four stretch receptors results in a decrease of the wingstroke frequency to about one-half normal. Interference with the normal timing of the stretch-receptor input (mechanically or by electrical stimulation) does not affect the normal wingstroke frequency. With respect to this sensory source the centrally generated motor output pattern is independent of input phase. The results are discussed briefly in relation to the question of central v. peripheral control of locomotion.
Free Flight of Aphids in the Laboratory
Authors: Kennedy J. S. , Booth C. O. 
Published: April 2021

ABSTRACT
The working principles, design and operation of an apparatus for keeping aphids in free flight are described. It consists of a large black-walled chamber with a battery of lights above a central opening in the roof and a fan blowing air down past them into the chamber. The aphid flies up toward the lights and is held at a small, fixed distance from them by adjusting the downward air speed to balance the aphid’s rate of climb, which can thus be recorded continuously. The uninterrupted first flight of virginoparous Aphis fabae in this chamber comprises a brief erratic opening phase, a long ‘cruising’ phase during which the rate of climb declines, and a final brief erratic phase when it falls to zero and the aphid flies away from the lights. Contact with a non-host surface will then restore the previous behaviour and a number of flights, similar but of decreasing duration, ensue until exhaustion at hr. During one flight and over a series of flights there are changes in the aphid’s responsiveness to the main lights and to light reflected from the chamber walls or from small objects such as leaves presented in the chamber. There appears to be an optimal (‘preferred’) light intensity for the positive phototaxis, which starts high but declines as the photokinesis (locomotor excitation, measured by the rate of climb) declines, until near exhaustion when the phototaxis becomes negative even to the lowest intensities.
Osmotic Regulation in the Brackish Water Teleost, Blennius Pholis
Authors: House C. R. 
Published: April 2021

ABSTRACT
The sodium effluxes between the blood and the medium have been studied in Blennius pholis in 10, 40 and 100% s.w. and in transfer from 40 to 100% s.w. under equilibrium conditions with the isotope 24Na. In addition the sodium influxes have been studied in 40 and 100% s.w. in a similar manner. The total flux in 100% s.w. has been found to be 100 mm. Na/1. blood/hr., and in 40 and 10% s.w. it has been found to be 20 mm. Na/1. blood/hr. The results are interpreted as showing that the presence or absence of exchange diffusion does not alter the estimation of the active sodium efflux across the gills in 100% s.w. The efflux experiments showed that the animal had a rapid adaptive ability to osmo-regulate upon transference from 40 to 100% s.w. The electric potential differences between the blood and external medium have been measured in animals adapted to 10, 40, 100 and 150% s.w. and the blood serum concentrations of sodium and chloride ions have been measured in these media. The mean potential differences ± standard deviation in 10, 40, 100 and 150% S.w. have been found to be – 3 ± 4·5 mV., +23 + 4 mV., +23 + 3 mV. and + 29·5 ± 5 mV. respectively (external medium taken as reference). The results are interpreted as showing that there is active outward excretion of chloride ions in animals adapted to 150, 100 and 40 % s.w. and active inward absorption of chloride ions in 10% s.w. and of sodium ions in animals adapted to 40 and 10% s.w. The drinking rate in 100 % s.w. has been calculated to be 27 mm. Na/kg. fish/hr. or 6 % body weight/hr.
A Method for Chronically Implanting Stimulating Electrodes into the Brains of Locusts, and Some Results of Stimulation
Authors: Fraser Rowell C. H. 
Published: April 2021

ABSTRACT
Methods are described for implanting permanent stainless-steel electrodes into the brains of locusts, for stimulating the brain under near-normal conditions, and for localizing the electrode subsequently. Threshold currents measured under these conditions are lower than those required in acute preparations, or if the animal is restrained. The results of stimulation are described for four common aspects of behaviour. These are antennal movement, locomotion, feeding and sexual behaviour. The effect of stimulation on antennal and locomotory movements largely confirms previous work on crickets. Feeding and foraging behaviour, which is a very common result, is shown to be almost completely determined by peripheral stimuli at the time of brain stimulation. The role of the latter is permissive or disinhibitory rather than causal or excitatory. Integrated sexual behaviour is occasionally inhibited, but never elicited, by stimulation. This contrasts with observations on crickets, and its implications are discussed.
The Swimming Speeds of Plaice Larvae
Authors: Ryland J. S. 
Published: April 2021

ABSTRACT
The swimming speeds attained by hatchery-reared plaice larvae have been determined by measurements made (a) in still water, and (b) against a current flowing through a long glass tube. In still water contact stimuli were used to initiate swimming. No optomotor response was found, and it was not possible to use the ‘fish-wheel’ of Bainbridge (1958). Larvae in the experimental tube stemmed the current for brief periods only, their position then being near the periphery of the upper quadrant. The speeds were found to show a linear relationship to larval length multiplied by the height of the post-anal musculature. Observations in still water show that these values correspond to those of steady swimming: they are not maximum speeds. Speeds ranged from about 1·5 cm./sec. when newly hatched to 9 cm./sec. in late larvae. Darting velocities of up to 15 cm./sec. were recorded with half-grown (stage III) larvae. In such larvae cruising speeds were about three fish-lengths (3L) per second, and the maxima about 10L/sec. The design of gear for collecting fish larvae at sea is discussed. Only a high-speed tow-net, towed at about ten times the velocity attainable by the largest larvae and giving almost no warning of its approach, can be considered to collect a quantitatively balanced sample.
The Development of Phototaxis in the Frog (Rana Temporaria)
Authors: Muntz W. R. A. 
Published: April 2021

ABSTRACT
Many experiments have shown that when a frog is disturbed it escapes towards the light, and that blue light is more effective than any other colour in guiding this response (see Pearse, 1910, for a review). A previously reported experiment (Muntz, 1962 b) has shown that the greater effectiveness of blue light is not simply due to the animals’ possessing a greater sensitivity to light in this part of the spectrum, but involves colour vision; the animals will respond preferentially to blue irrespective of the intensity or saturation of the stimulating lights. They will, for example, choose a blue illuminated window in preference to a window illuminated by an additive mixture of the same blue light together with a green light, in spite of the fact that the latter window contains as much blue as the former, as well as the green.