bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Growth of Fish
Authors: Gray J. 
Published: April 2021

ABSTRACT
For the egg of any given species of animal there exists a range of temperature within which the embryo is capable of developing into a normal healthy organism. If the temperature of incubation be raised, the velocity of development of a cold-blooded embryo is increased ; if the temperature be lowered the velocity is decreased. In both cases the result is qualitatively similar; the mutual proportions of the various tissues and organs are, as far as is known, much the same in the final products. It is improbable that the velocity of every process which occurs during development is equally affected by changes in temperature; some processes will tend to respond to a greater extent than others. If, therefore, development were simply the summation of each separate process we would expect to find that the relative size of each organ would vary with the temperature at which the egg had been incubated. Consider, for example, two cells each capable of reproducing itself in 12 hours at 10° C. but differing from each other in their temperature coefficients of growth. If a rise of 10° C. increased the rate of development of one cell by 100 per cent., and that of the other by 200 per cent., then at the end of 12 hours’ development at 20° C. there would be five cells of one type for every seven of the other, whereas at 10° C. the numbers would be equal. The very fact that marked variations in the proportionate size of organs and tissues do not apparently characterise variations in the temperature of incubation indicates that, to some extent, the velocity of development of any one type of tissue or the velocity of any one embryological process is dependent on the velocity of other parallel processes, or that they are all controlled by the velocity of one fundamental reaction. By varying the temperature of incubation of the eggs of the trout, a convenient means exists of determining how far this picture of the embryological development of a fish is true, or how far some processes can be regarded as independent reactions.
On the Nature of Hereditary Size Limitation
Authors: Robb R. Cumming 
Published: April 2021

ABSTRACT
If it could be shown that the determination of organ size in the animal body is not reached by an independent process, but that the magnitude of any one structure is determined by that of others, such evidence, if of a strictly quantitative nature, would tend to affirm the existence of a physical mechanism regulating the relative growth of body components. It is the object of this paper to present such evidence, and to describe a model from physical chemistry which lends a reasonable interpretation to the diversification observed in the ontogenetic and phylogenetic history of organ size.
The Effect of Extracts of Suprarenal Cortex on the Blood Calcium
Authors: Mirvish L. , Bosman L. P. 
Published: April 2021

ABSTRACT
An extract has been prepared from the suprarenal cortex, which, when injected into rabbits, lowers the blood calcium to the extent of about 30 per cent. ; the maximum fall occurs after 24 hours, and returns to normal in about 48 hours. The extract prepared from the suprarenal cortex resembles that obtained from ovary and corpus luteum, both in physical characteristics, and in the production of a typical response on the part of the blood calcium. It would appear that the hormone of the suprarenal cortex that is capable of lowering the blood calcium is very similar and possibly identical with the hormone of the ovary, having the same function. A definite relationship has been established between the suprarenal cortex and the ovary, justifying the long-suspected connection between the two glands.
The Growth of Blackbeetles and of Cockroaches on Artificial and on Incomplete Diets. Part I
Authors: Żabiński Jan 
Published: April 2021

ABSTRACT
The normal development cycle at 25 ° of the blackbeetle lasts about 12 months, that of the cockroach about 3 months, so that in comparing the velocity of growth of these insects the ratio 4 : 1 may be taken (1 month is equivalent to 1 week). During approximately one-third of these periods the insects grow equally rapidly on synthetic as on normal diets. The entire development cycle of the blackbeetle could not be completed on a synthetic diet. The larvae attain barely one-third of the normal weight during the normal post-embryonic development period, after which they die, without, however, losing weight to any great extent. Blackbeetle larvae put on synthetic diets half-way through the growth period can attain sexual maturity. The cockroach is able to complete its entire development cycle on a synthetic diet, even when the only nitrogenous constituent is glycine. The symptoms of avitaminosis, which appear after the above-stated time, are lack of mobility, the appearance of a matt surface of the chitin envelope; should sexual maturity be attained, small dimensions and infertility are characteristic symptoms. Ovalbumin may be replaced by biologically deficient proteins such as gelatin, or even by glycine, without in any way affecting the character of growth. By diminishing the percentage nitrogen content in diets the rate of growth is distinctly diminished, but at the same time the period of its duration is prolonged. Blackbeetles and cockroaches are exceptionally resistant to the absence of nitrogenous constituents in their food, being able to maintain their body-weight over periods of time equal in length to that of the entire normal post-embryonic cycle. Even after prolonged inhibition of growth, the administration of a normal diet allows these animals to resume growth and attain sexual maturity, including the production of normal young. The rate of growth of insects which have been given normal food after long periods of inhibition of growth is independent of the actual age of the inSect, and corresponds to that which the animal possessed at the commencement of the period of inhibition. These insects do not survive long if fed upon exclusively protein diets, in the absence of carbohydrates. The addition of small quantities of butter, yeast, or vitamin B extracts to synthetic and complete diets does not lead to any enhancement of growth.
A Study of the Afferent Pathways of the Dragonfly Lateral Ocellus From Extracellularly Recorded Spike Discharges
Authors: Rosser B. L. 
Published: April 2021

ABSTRACT
The lateral ocellar nerve of adult dragonflies contains at least two kinds of afferent nerve fibres: the ‘giant’ afferent and small afferents. Efferent fibres are also present, but are not described here. The afferent fibres and receptor axons were studied by extracellular recording of their spike discharges. Experiments using light and electrical (D.C.) stimulation and the application of magnesium were performed. Responses of the giant afferent were analysed into a number of exponential components. The number could be altered experimentally. The giant afferent shows the phenomenon of ‘delayed response’, a delayed onset of the off-response to brief light stimuli. A qualitative model for delayed responses, incorporating the exponential components, is described. It is concluded that the small afferents behave in accordance with Ruck ‘s model of ocellar of functioning but that the giant afferent does not. It is proposed that inhibion in the giant afferent fibre is produced electrotonically, but there may be a synaptic contribution also."
Quantitative Analysis of the Speed of Snakes as A Function of Peg Spacing
Authors: Bennet S. , McConnell T. , Trubatch S. L. 
Published: April 2021

ABSTRACT
The speed of snakes moving by lateral undulation was measured on a smooth board studded with equally spaced pegs arranged in a hexagonal pattern. For some snakes speed was drastically reduced (by as much as 50%) as the ratio of body length to peg spacing was reduced from values as high as twelve to values near or below three. Speed is also influenced by the relative orientation of the pegs contacted by the moving snake. Snakes which can sidewind use this ability to maintain a constant speed when the number of contact points available is insufficient for continuous lateral undulation."
Urinary Bladder Volume and the Reabsorption of Water from the Urine of Crabs
Authors: Riegel J. A. , Lockwood A. P. M. , Norfolk J. R. W. , Bulleid N. C. , Taylor P. A. 
Published: April 2021

ABSTRACT
Measurements have been made to determine the blood volume, bladder volume, clearance of 131I-sodium diatrizoate and U/H for diatrizoate in the crabs Carcinus maenas and Macropipus (Portunus) depurator. Observed values of clearance blood volume and bladder volume in the two species at 18 °C were: Clearance (as % blood volume per day), Macropipus 56.1±14.5; Carcinus 27.1±5.8; Blood volume (as % body weight), Macropipus 21.0±4.0; Carcinus 19.2±3.0; Bladder volume (as % blood volume), Macropipus 12.1 ±5.0; Carcinus 11.0±8.0. It is shown that the measured U/H differs from that to be expected if no reabsorption of water or secretion of diatrizoate occurs. 14C-inulin and 51Cr-EDTA are excreted in an essentially similar manner to 131I-diatrizoate by Carcinus, implying that any active secretion of diatrizoate must be small in magnitude. Injections of ethacrynic acid decrease the U/H ratio for diatrizoate relative to that in control Carcinus injected with sea water. In some Carcinus the concentration of diatrizoate in the urine comes to exceed that initially present in the blood. Both these points are taken, with 3, as support for the conclusion that water can be withdrawn from the primary urine of Carcinus.
Attachment of Giardia - A Hydrodynamic Model Based on Flagellar Activity
Authors: Holberton D. V. 
Published: April 2021

ABSTRACT
The attachment of Giardia trophozoites can be modelled by viscous-flow equations demonstrating that a suction pressure arises from the viscous stress of a fluid flow led beneath the cell by flagellar activity. Changing fluid velocity is less significant in generating suction. Over the range of flagellar wave parameters observed from cells attached to glass, suction pressure may reach io2 dynes cm-2. Expressions for the bending of a thick disc under normal load allow an estimate of suction pressure in situ from its deforming effect on the gut-cell cortex. Allowing for alternative boundary states, calculations suggest that suction pressures close to 102 dynes cm-2 account for the deformations measured from electron micrographs. The shape assumed by a ventro-lateral flange determines the magnitude of the developed suction pressure and may constitute a control mechanism of attachment and detachment.
A Critical Examination of the Physical and Adrenergic Factors Affecting Blood Flow Through the Gills of the Rainbow Trout
Authors: Wood Chris M. 
Published: April 2021

ABSTRACT
Perfusion of the whole gill of Salmo gairdneri with a Newtonian medium under different afferent and efferent pressures has revealed considerable passive distensibility in the branchial vasculature. A capacity for autoregulation may exist. Changes in dorsal aortic pressure are relatively more effective than changes in ventral aortic pressure in altering branchial vascular resistance. Measurements of changes in vascular tone in the gills determined as the ratio of resistances in the experimental and the control states at one point on the pressure differential/flow profile can be extrapolated to the rest of the profile when the comparisons have been made at the same flow. True catecholamines cause a maximum 60 % decrease in vascular resistance (at the same flow) by stimulation of β1-adrenergic receptors in the gills. Branchial dimensions and perfusate viscosities have been measured and, together with the pressure differential/flow data, have been used to evaluate the Muir-Brown model of vascular resistance in the teleost gill. The model, with some limitations, fits the present data and suggests that both active and passive resistance changes are best explained by alterations in the number of secondary lamellae perfused.
A Study of the Malpighian Tubules of the Pill Millipede, Glomeris Marginata (Villers)
Authors: Farquharson Patricia Anne 
Published: April 2021

ABSTRACT
Isolated Malpighian tubules of Glomeris produce fluid which is identical to the bathing media with respect to ion concentrations and osmotic pressure. The tubules secrete normally in a potassium-free Ringer, but they cease to function in a sodium-free Ringer. The rate of fluid production is dependent on the availability of sodium ions, but it is also inhibited by higher concentrations (25 mM/1) of potassium ions. Throughout a wide variation in concentrations of sodium and potassium ions in the bathing Ringer, the concentrations of these ions in the tubule fluid are the same as their concentrations in the Ringer. Fluid production by the tubules of Glomeris is inhibited by ouabain at a concentration of 5 × 10−6 M/1 or greater. The rate of fluid production varies inversely with the osmotic pressure, and the secreted fluid remains approximately isosmotic to the bathing media. No electrical potential difference could be recorded across the tubule wall.
A Study of the Malpighian Tubules of the Pill Millipede, Glomeris Marginata (Villers)
Authors: Farquharson Patricia Anne 
Published: April 2021

ABSTRACT
Tubule fluid:medium ratios (TF/M) have been measured for inulin, glucose, LMWD and HMWD. These TF/M ratios were surprisingly high. The tubule appears to act as a molecular filter; that is to say, molecules move through the tubule wall in inverse relation to their size. This is best illustrated using polyvinyl pyrrolidone as a tracer. The molecular size distribution of PVP fractions present in tubule fluid differs markedly from the molecular size distribution of PVP in the bathing Ringer. No correlation can be made between the inulin and glucose TF/M and the rate of fluid production. However, the inverse relationship between TF/M and rate of fluid production for dextrans indicates a molecular sieving effect. The significance of these results is discussed with reference to models of fluid transport.
The Effect of Low-Calcium Sea Water and Actinomycin-D on the Sodium Metabolism of Fundulus Kansae*
Authors: Fleming Warren R. , Nichols James , Potts W. T. W. 
Published: April 2021

ABSTRACT
Transfer of Fundulus kansae from 80% sea water to a low-calcium water containing 0·4 mm/1 Ca2+ caused a sharp rise in sodium efflux and a change in the kinetic pattern of efflux. A transient drop in whole-body sodium levels occurred within 1·2 days after transfer. Both sodium and potassium levels were normal after 9 days exposure to low-calcium saline. Transfer into low-calcium sea water increased the rate of incorporation of radio-phosphorus into gill RNA. Actinomycin-D blocked the stimulation of sodium turnover after transfer into low-calcium sea water. It did not affect the whole-body sodium or potassium levels of long-term sea-water adapted animals. Actinomycin-D reduced the sodium efflux of short-term sea-water adapted animals regardless of the environmental calcium concentration. The antibiotic also upset the balance of sodium fluxes in those animals held in low-calcium sea water. It is suggested that in addition to the generalized effect of calcium on perme-ability to monovalent ions and water, calcium serves to inhibit some of the synthetic processes involved in regulating sodium metabolism, and also serves to stabilize the metabolic machinery already present.
The Water Balance of a Serpulid Polychaete, Mercierella Enigmatica (Fauvel)
Authors: Skaer Helen Le B. 
Published: April 2021

ABSTRACT
The serpulid polychaete Mercierella enigmática is found naturally in a wide range of salinities – from fresh water to 150% sea water (&lt; 1–55‰, &lt; 25·8–1421 mOsm). Changes in body weight, blood volume and blood osmolality have been measured both during and after equilibration of animals with media of altered salinity. The blood remains similar in osmolality to the external medium over a very wide range of salinity (43–1620 mOsm); osmoregulation occurs only at the lowest limit of the natural range. Mercierella enigmática shows volume regulation; after 4 days of equilibration with a medium of altered salinity the blood volume shows much less change than the blood concentration. During equilibration there appear to be passive movements of both water and salts between the animals and their environment.
The Water Balance of a Serpulid Polychaete, Mercierella Enigmatica (Fauvel)
Authors: Skaer Helen Le B. 
Published: April 2021

ABSTRACT
Mercierella enigmatica, a serpulid polychaete, lives in water ranging in concentration from fresh water to 150% sea water (&lt; 1–55 ‰). The concentrations of five inorganic ions (Na+, K+, Ca2+, Mg2+ and Cl−) in the blood have been measured both during and after equilibration of the animals with media of altered salinity. The concentrations of calcium and potassium have also been measured in filtrates of the blood from animals equilibrated in three media of differing salinity. Concentrations of all the ions measured vary linearly with the concentration of the external medium. The levels of sodium, calcium (in filtered blood) and chloride are near the isionic line, while those of magnesium and potassium (even in filtered blood) are slightly higher in the blood over the whole range.
Physiology of Insect Rhythms
Authors: Truman James W. , Riddiford Lynn M. 
Published: April 2021

ABSTRACT
The moulting process of insects is governed by the interaction of three hormones: prothoracicotropic hormone (PTTH), juvenile hormone, and ecdysone (see Doane, 1973; Wyatt, 1972; Wigglesworth, 1971 for recent reviews). To initiate the moult the brain releases PTTH which causes the secretion of ecdysone from the prothoracic glands. Ecdysone in turn triggers the detachment of the epidermis from the old cuticle and the subsequent secretion of the new cuticle. Whether this new cuticle is larval, pupal, or adult depends on the titre of juvenile hormone at the time of ecdysone secretion.
The Nervous Control of Autotomy in Carcinus Maenas
Authors: McVean Alistair 
Published: April 2021

ABSTRACT
The musculature which operates the coxopodite and basi-ischiopodite of the fifth limbs of the common shore crab has been described. A comparison between the basi-ischiopodite depressor and anterior levator has shown that the levator muscle has a large reserve with which it effects limb severance at autotomy. Recordings from the nerve to the anterior levator muscle show that it is innervated by a tonic and phasic unit together with another, large spiking unit, which is activated at autotomy. Transverse sections of the nerve to the anterior levator show that it contains giant axons. Intracellular recordings from the anterior levator together with whole muscle tension confirm that there are three motor neurones, which produce a slow, fast and ‘giant twitch ‘response in the muscle.
Response Modification by the Central Flight Oscillator of Locusts
Authors: Camhi Jeffrey M. , Hinkle Maija 
Published: April 2021

ABSTRACT
Flying locusts respond to changes in wind-velocity or wind-angle with abdomen posturing in the vertical or horizontal plane, respectively. Receptor hairs on the head sense these wind parameters and evoke the responses in specific abdominal muscles. Records were made from individually identifiable motoneurones to these muscles during the performance of wind-evoked behaviour. During flight these motoneurones are excited by the central flight oscillator and show a burst rhythm at flight frequency. Wind stimuli modulate the number of spikes per burst in this rhythm, but do not affect its frequency or phase with respect to the wingbeat. Changes in wind-velocity and wind-angle evoke different relationships of muscle synergy and antagonism, resulting in the two different patterns of behaviour performed by the same group of muscles. During flightless periods the motoneurones show no flight rhythm, but only the much lower frequency ventilatory rhythm. At these times they are unresponsive to wind stimuli.
Effects of Pressure and Temperature Changes On the Flagellar Movement of Crithidia Oncopelti
Authors: Coakley C. J. , Holwill M. E. J. 
Published: April 2021

ABSTRACT
The combined effects of hydrostatic pressure and temperature on the flagellar movements of Crithidia oncopelti were studied. Provided that a critical pressure, which depended on the temperature, was not exceeded, the application of pressure produced an initial increase in flagellar frequency ; the frequency then fell to a steady level which was below the value obtaining before the application of pressure. The compression also caused a transient increase in the number of organisms propagating coherent waves, an increase in the average wave amplitude, and asymmetric waveforms with decreasing wavelength and amplitude towards the flagellum tip. The results are consistent with the hypotheses that the observed flagellar response is due to (a) changes in the equilibrium of a reversible enzyme denaturation process, and (b) changes in the rate of decomposition of an enzyme–substrate complex. Values of the volume, enthalpy and entropy changes associated with each process are derived and their significance for mechanism is discussed.
Electrophysiology of the Giant Nerve Cell Bodies of Limnaea Stagnalis (L.) (Gastropoda: Pulmonata)
Authors: Sattelle D. B. 
Published: April 2021

ABSTRACT
A mean resting potential of − 53·3 (S.D.± 2·7) mV has been obtained for 23 neurones of the parietal and visceral ganglia of Limnaea stagnalis (L.). Changes in the resting potential of between 28 and 43 mV accompany tenfold changes in [K+0]. A modified constant-field equation accounts for the behaviour of most cells over the range of external potassium concentrations from 0·5 to 10·0 mM/1. Mean values have been estimated for [K+1], 56·2 (S.D.±9·O) mM/1 and PNa/PK, 0·117 (S.D. ±0·028). Investigations on the ionic basis of action potential generation have revealed two cell types which can be distinguished according to the behaviour of their action potentials in sodium-free Ringer. Sodium-sensitive cells are unable to support action potentials for more than 8−10 min in the absence of sodium. Sodium slopes of between 29 and 37 mV per decade change in [Na+0] have been found for these cells. Tetro-dotoxin (5 × 10−5 M) usually blocks action potentials in these neurones. Calcium-free Ringer produces a marked reduction in the overshoot potential and calcium slopes of about 18 mV per decade change in [Ca2+0] are found. Manganous chloride only partially reduces the action potential overshoot in these cells at concentrations of 10 HIM/I. Sodium-insensitive neurones maintain action potentials in the absence of external sodium. Stimulation only slightly reduces the amplitude of the action potential under these conditions and such cells are readily accessible to potassium ions in the bathing medium. A calcium-slope of 29 mV per decade change in [Ca2+0] has been observed in these cells in the absence of external sodium. It is concluded that both sodium and calcium ions can be involved in the generation of the action potential in neurones of Limnaea stagnalis, their relative contribution varying in different cells.
The Initiation and Conduction of Action Potentials in the Optic Nerve of Tritonia
Authors: Chase Ronald 
Published: April 2021

ABSTRACT
As noted in the preceding article (Chase, 1974), an optic nerve origin for photoreceptor spikes in the mollusc Tritonia diomedia is indicated by the small size and frequent absence of somatic action potentials. Axonal trigger sites are the rule for invertebrate ganglion cells (Tauc, 1962) and most peripheral sensory neurones (Edwards & Ottoson, 1958), but there are exceptions (Mellon & Kennedy, 1964) and the issue has not been well investigated in molluscan sensory neurones. Recently Alkon & Fuortes (1972) found evidence for axonal spike initiation in photoreceptors of the nudibranch Hermissenda. In Tritonia, also a nudibranch, the receptor fibres are several millimetres longer than in Hermissenda, and the optic nerve itself, apparently composed exclusively of these fibres, measures about 2·0 mm. These experiments take advantage of the long optic nerve in Tritonia to examine in detail the origin of photoreceptor spikes.