bluuebunny/crossref_metadata_2025 huggingface dataset:
The Oxygen Consumption of An Echiuroid, Bonellia viridis Rolando
Authors: Brafield A. E.
Published: April 2021

The oxygen consumption of the echiuroid Bonellia viridis has been investigated by means of a continuous-flow polarographic respirometer. The general rate of oxygen consumption per unit dry weight is similar to that characteristic of polychaetes, and declines exponentially with increasing body size. The rate of oxygen consumption rises in the light and falls again if darkness is restored. The oxygen consumption of the isolated proboscis plus that of the isolated body region corresponds closely to that of the entire animal. The oxygen consumption per unit dry weight of the proboscis is considerably higher than that of the body region. The oxygen consumption of an isolated body region increases in the presence of light, but that of an isolated proboscis does not. These findings are discussed in relation to the biology of the animal, observed muscular activity, and the occurrence of the pigment bonellin.
Effects of Sub-Lethal High Temperature on An Insect, Rhodnius prolixus (Stål.)
Authors: Okasha A. Y. K.
Published: April 2021

Protease activity of the mid-gut of 5th-stage larvae was studied under different conditions. The activity is not detectable in the unfed insect, but increases after feeding, reaching a maximum just before ecdysis. In insects kept at high temperature immediately after feeding, protease activity is approximately normal for the first 2 days, but thereafter it decreases; after transfer to normal temperature the activity starts to increase. Decapitation reduces protease activity under normal temperature conditions. Possible hormonal control of digestion is discussed, and it is suggested that the brain hormone is involved. The concentration of free amino acids in the haemolymph greatly increases at high temperature, but returns to the normal level after transfer to normal temperature. The adjustment to the normal level does not occur if the insects are decapitated immediately after transfer. The concentration of protein in the haemolymph at high temperature does not recover from the initial decrease. After transfer to normal temperature there is a tendency to a very slow increase. Protein synthesis is impaired at high temperature and thus amino acids accumulate in the haemolymph, since they are not used in protein metabolism. It is concluded that the impairment of protein synthesis results in the cessation of moulting, of cell division in the epidermis during wound healing, and of the secretion of the brain hormone
Changes in the Nucleic Acid and Protein Composition of the Nasal Glands from the Duck (Anas platyrhynchos) During the Period of Adaptation to Hypertonic Saline*
Authors: Holmes W. N. , Stewart D. J.
Published: April 2021

After transfer of the freshwater-maintained ducks to a hypertonic saline regimen the wet weight, the protein content and the RNA content of the nasal glands showed a two-fold increase. The RNA content of the nasal glands was maximal after approximately 24 hr. whereas the maximum wet weight and protein content did not occur until after approximately 14 days of exposure to hypertonic saline. The DNA content of the nasal glands increased by approximately 42% during the period of adaptation to hypertonic saline and at the same time the weight of gland per unit DNA increased by about 58%. The wet weights, nucleic acid concentrations and the protein concentrations of Harderian glands, liver, kidney and adrenal glands did not change upon adaptation of the ducks to the hypertonic saline regimen for 14 days. Upon return of the birds to the freshwater diet, the weight, protein content and RNA content of the nasal gland declined. No loss of DNA was apparent. The weight of the gland per unit DNA and the protein content per unit DNA and the total RNA content of the nasal glands all returned to the level observed in the freshwater-adapted birds. When the birds were again transferred to the hypertonic saline diet the nasal glands returned to the state of development previously observed when the birds were maintained on the hypertonic saline regimen. The significance of these data in relation to the changes known to occur in the active sodium-transporting properties of the nasal gland are discussed.
A Method of Estimating the Relative Volumes of Water Flowing Over the Different Gills of A Freshwater Fish
Authors: Paling J. E.
Published: April 2021

A technique is described which uses marker parasites to estimate the relative volumes of water flowing over the different gills of a freshwater fish. It was found that in brown trout from Windermere most of the respiratory current flows over the second and third pairs of gills, less flows over the first pair on each side and least of all across the most posterior pairs of gill. Similarly, the median pair of gill slits carries more of the respiratory current than any of the other slits whereas first and fifth pairs of gill slits together carry only about one-sixth of the total water flow. Hatchery-bred brown trout showed a slight but significant difference in pattern of water movement over their gills following vigorous exercise. Possible reasons for this are discussed.
Analysis of the Distribution of Sodium, Potassium and Osmotic Pressure in the Urine of Crayfishes
Authors: Riegel J. A.
Published: April 2021

Osmotic pressures of urine removed from the crayfish antennal gland have been re-measured. The results fail to confirm those obtained earlier which indicated a marked fall in the distal portion of the antennal gland. The possible reasons for this discrepancy are discussed. No significant fraction of the sodium in the urine is localized within the formed bodies found there. Potassium is localized within the formed bodies, but the relative amount cannot be ascertained. There is an inverse relationship between sodium and potassium concentrations in the tubular (distal) portions of the antennal gland. No such relationship exists in the coelomosac and labyrinth (proximal) portions of the gland.
Inherent Asymmetry and Reflex Modulation of the Locust Flight Motor Pattern
Authors: Wilson Donald M.
Published: April 2021

In this paper I will present new data and ideas on two interrelated questions regarding the nervous control of insect flight. The answers to these two questions may be important for understanding other aspects of insect behaviour as well. The two problems are: (1) How perfect is the motor score which is built into the thoracic ganglia? (2) How is this motor score modified when anatomical damage makes the inherent score inappropriate? In addition to providing partial answers to these questions the results show that the phenomenon of adaptation of locomotory patterns to limb loss, called Plasticität by Bethe (1930), does not imply that locomotion is coordinated purely by proprioceptive reflexes. Although Bethe did not hold this view, later authors have often interpreted his work in this sense. They show also that two categories of possible central organization of locomotory behaviour, motor scores or sensory templates (the ‘motor tapes’ and ‘sensory tapes’ of Hoyle, 1964), are not mutually exclusive.
Dishabituation and Arousal in the Response of Single Nerve Cells in an Insect Brain
Authors: Fraser Rowell C. H. , Horn G.
Published: April 2021

The background activity of neurones in the tritocerebrum of the locust responding to objects moved in the contralateral visual field can be influenced, possibly trans-synaptically, by electrical stimulation of the contralateral neck connective. These changes in background activity are always excitatory and may outlast the period of stimulation by several minutes. The effect of stimulating the ipsilateral cord on the discharge is weak or non-existent. If the contralateral connective is shocked when the response to a moving disk has waned, the recorded cell responds to the disk again. The response continues at a high level for many presentations following stimulation of the connective. Such dishabituation does not follow stimulation of the ipsilateral neck connective. Dishabituation sometimes occurs ‘spontaneously’ and cannot be accounted for as a recovery following a lapse of time. Some units show diurnal variations in their responsiveness to visual stimulation.
Effect of Drugs On Luminescence in Larval Fireflies
Authors: Carlson Albert D.
Published: April 2021

Synephrine and other related monophenolic drugs were tested for potency of luminescence induction in the extirpated lantern of larval fireflies. Synephrine was found to be the most potent drug so far tested, with a threshold concentration of 10−6 M. Immersion of glowing lanterns in a solution containing 10−8 M synephrine and 10−8m-KCN resulted in rapid extinction of luminescence. Luminescence extinction times in KCN were found to be proportional to synephrine concentration and suggest that only a small ATP pool exists in the lantern. It is hypothesized that synephrine must stimulate ATP production in order to maintain high luminescence intensities. The vertebrate adrenergic blocking agent, dichloroisoproterenol (D.C.I.), was found to slowly induce luminescence which eventually declined to extinction. Synephrine was ineffective in luminescence induction after the declining phase of D.C.I. action began. A close analogue of D.C.I., isoproterenol, acted in a weak but similar manner to synephrine. It is suggested that D.C.I. prevents synephrine action by blocking the photocyte receptor sites.
Ionic Composition of Haemolymph and Nervous Function in the Cockroach, Periplaneta Americana L
Authors: Pichon Y. , Boistel J.
Published: April 2021

Resting and action potentials have been recorded in giant axons of the cockroach when the intact nerve cord was bathed in the insect’s own haemolymph. Low resting potentials (43·0 + 4·8 mV.) and large action potentials (105·1 + 6·8 mV.) were obtained in these preparations as compared with those recorded in de-sheathed nerve cords. Recordings of the maximum rates of rise and fall have shown that the shape of the action potential was essentially similar in de-sheathed preparations and in intact nerve cords. These results have been discussed in terms of the unequal distribution of ions between the haemolymph, the extracellular fluid and the axoplasm of the giant axons. The low measured resting potential agrees with a K+ concentration in the haemolymph of about 20 mM./l., a value which is only slightly lower than the measured one (Pichon, 1963). The occurrence of large action potentials in these apparently depolarized axons may be related to the stabilizing action of divalent cations such as Ca2+ which are contained in the extracellular fluid in relatively large amounts. The very large recorded overshoots (62·1 ±7·0 mV.) may be linked with a low sodium concentration in the axoplasm and a high sodium concentration in the extracellular fluid of the giant axons of intact nerve cords, thus resulting in a high sodium equilibrium potential, ENa.
The Action of Iontophoretically Applied Glutamate On Insect Muscle Fibres
Authors: Beránek R. , Miller P. L.
Published: April 2021

Electrophoretic application of L-glutamate from glass capillary micro-pipettes was used to investigate the ‘spot sensitivity’ of the membrane of coxal adductor muscle fibres from adult specimens of Schistocercagregaria Forskål and Locusta migratoria (L.). Circumscribed spots could be detected on the fibre surface where brief applications of L-glutamate produced transient depolarizations (glutamate potentials). Extracellular recording of excitatory junction potentials revealed that focal points of glutamate sensitivity are closely related to, and probably identical with, neuromuscular junctions. Large doses readily de-sensitized the membrane to L-glutamate for periods greatly exceeding the duration of the glutamate potentials. In chronically denervated muscles peaks of sensitivity could still be detected. Spots sensitive to L-glutamate were not depolarized by D-glutamate. The equilibrium point for glutamate potentials coincides with the equilibrium point of miniature excitatory potentials and lies between –10 and –25 mV.
The Action of the Eyecup Muscles of the Crab, Carcinus, During Optokinetic Movements
Authors: Burrows M. , Horridge G. A.
Published: April 2021

The actions of the nine eyecup muscles of the crab during horizontal optokinetic movements are described. Each muscle includes a wide spectrum of fibre types, ranging from phasic, with sarcomere lengths of 3–4 μm., through intermediate, to tonic fibres with sarcomeres of 10–12 μm. Each muscle receives at least one slow and one fast motoneuron, but no inhibitory supply. The slow axons predominantly innervate the tonic muscle fibres while the fast axons innervate the phasic ones. Slow movement and the position of the eyecup in space are controlled by the frequency of slow motoneuron discharges. All muscles collaborate at every position. The phasic system is recruited during rapid eyecup movements of large amplitude. In optokinetic nystagmus the exact form of the impulse sequences are described for each muscle. They are the consequence of a visually driven central programme which takes no account of the movement which it generates. Movements in opposite directions involve different central programmes; the one is not merely the reverse of the other. There is no effective proprioceptive feedback from the eyecup joint or from muscle tension receptors.
Efferent Copy and Voluntary Eyecup Movement in the Crab, Carcinus
Authors: Horridge G. A. , Burrows M.
Published: April 2021

Use is made of the fact that a freely moving blind eyecup is driven by movement perceived by the opposite seeing eye when the crab is in an optomotor drum. Forced extension of the seeing eyecup causes movement of the other blinded eyecup in the opposite direction, because it is driven by the perceived relative motion. Voluntary extension of the seeing eyecup causes no movement of the other blinded eyecup, although simultaneous oscillation of a striped drum round the crab is seen perfectly. Preventing voluntary extension of the seeing eyecup with a mechanical stop causes no movement of the other, blinded, eyecup. With both eyes blinded, or with the crab in the dark, voluntary or forced movement of one eyecup causes no movement of the other. This behaviour is that expected of an animal which can retract and extend either eyecup in the light or in the dark without disturbing the other, but no simple model is compatible with all the experiments."
Electrophysiological Studies On Initiation and Reversal of the Heart Beat in Ciona Intestinalis*
Authors: Anderson Margaret
Published: April 2021

Electrophysiological techniques have been used to define pacemaker characteristics and organization in the heart of the tunicate Ciona intestinalis. The frequency of spontaneous beat initiation was regular or irregular for a given period of time; in any single heart, these frequency modes intermittently changed from one to the other in no regular order. Reversals could take place immediately, after a pause, or after collisions. Trains of electrical stimuli applied to the ends of the heart could drive propagated contractions at a frequency of up to 2·6/sec., and dominance could be controlled by altering the frequency and/or intensity of the stimuli. Each end gave a characteristic response to increasing frequency of driving, and the threshold for one-to-one driving was frequency-dependent. When the middle of a heart was ligatured, the two ends were independently active. Visceral ends exhibited regularly varying levels of high and low frequency with a period of several minutes, whereas the frequency levels of the hypobranchial ends varied irregularly. Intracellular resting potentials were approximately –50 mV., and propagated action potentials associated with contractile events did not show ‘overshoot.’ Partial electrical responses were affiliated with weak or failing mechanical events, and complex, double-peaked intracellular potentials were often associated with collisions. In some cases a cell could show electrical activity that was completely dissociated from the mechanical response of the whole heart. Excitation thus probably spreads passively between cells, and multiple foci of activity may co-exist at any given time. From electrophysiological and anatomical data, an hypothesis is proposed to explain the observed mechanical activity on the basis of the interactions of individual cells and higher-order interactions among groups of cells.
Reversal of A Visual Preference in Octopus After Removal of the Vertical Lobe
Authors: Young J. Z.
Published: April 2021

Normal octopuses tend to attack a black disk more often than a white one, when they are shown against a white background. The difference is not present with a grey background. After removal of the vertical lobe the preference is reversed and attacks are now more frequent at a white than at a black figure, when on a white ground.
Tarsal Receptors and Leg Reflexes in the Locust and Grasshopper
Authors: Runion H. I. , Usherwood P. N. R.
Published: April 2021

The physiological properties of hair sensilla found on the metathoracic tarsal segments of the locust and grasshopper are described. The sensilla trichodea are phasically responsive mechanoreceptors. The discharge frequency of these receptors is proportional to the velocity of displacement of the sensory appendage. Phase-related responses are obtained with sinusoidal inputs less than 100 Hz. With higher input frequencies the receptors respond asynchronously. The tarsal sensilla signal contact of the tarsal segments with the substratum and changes in the load on the metathoracic leg. Reflexes involving these tarsal receptors and the ‘fast’ and ‘slow’ excitatory and inhibitory neurones which innervate the metathoracic extensor tibiae muscle have been demonstrated and appear to play a significant role during postural and walking activity.
Desiccation Survival of the Infective Larva of Haemonchus Contortus
Authors: Ellenby C.
Published: April 2021

The ensheathed larva of Haemonchus contortus is far better at surviving desiccation than the exsheathed form. Using interference microscopy, it is shown that, although the sheath is freely permeable to water, the ensheathed larva loses water much more slowly than the exsheathed larva. Close inspection of partially dry ensheathed larvae shows that the sheath becomes dry first and that this slows the rate at which the larva it contains loses water. The results are discussed in relation to other examples among nematodes where desiccation survival appears to be associated with mechanisms to slow the rate of drying.
Oxygen Consumption and Gill Water Flow in the Dogfish Scyliorhinus Canicula L
Authors: Hughes G. M. , Umezawa Shun-Ichi
Published: April 2021

Determinations of the standard oxygen consumption of the dogfish Scyliorhinus canicula, by several different methods, gave values in the range of 20-55 c.c./kg./hr. at 12° C. When the rate of water flow over the resting fish is increased, there is an increase in oxygen consumption, but no marked change in respiratory frequency at the flow rates studied. An increase of respiratory frequency took place when the of the inspired water was reduced. The ventilation volume of the dogfish was measured by collecting the water in chambers after it had passed over the gills. The resting ventilation volume was about 120 c.c./min./kg. at 12° C. The relationship between the flow across the gills and the imposed hydrostatic pressure gradient (Δp) showed a linear relationship. The fish was unable to continue pumping water across the gills against adverse gradients in excess of 0·7 cm. H2O. When the flow across the gills was relatively low, utilization of oxygen of at least 70% was observed, but with increasing flow rates this fell to between 40 and 50%.
The Effect of Loading the Respiratory Pumps on the Oxygen Consumption of Callionymus Lyra
Authors: Hughes G. M. , Knights B.
Published: April 2021

A comparative study of the respiration of fishes from different ecological niches has shown that certain species are suited for the study of particular aspects of respiratory function because of their structure and physiological adaptations. In this context the study of the generally less active bottom-living forms has advantages where movements of the fish must be limited by the experimental arrangement. In the case of the dragonet, Callionymus lyra, there is the added advantage that water issuing from the opercular cavities can be readily collected into tubes fixed round the external openings without impairing the action of the opercular valves. These preparations proved of great value in making direct measurements of the ventilation volume under varying conditions (Hughes & Umezawa, 1968a). The relationship between ventilation volume and muscular activity was also studied very conveniently in this species (Hughes & Ballintijn, 1968).
The Hydraulic System of Urechis Caupo Fisher & Macginitie
Authors: Chapman G.
Published: April 2021

The hydrostatic pressures recorded in the coelom of Urechis during peristalsis, irrigation, burrowing and hind-gut ventilation have been recorded continuously. The main muscular activities except burrowing take place at pressures of a few centimetres of water and, it is suggested, are mainly carried out by the outer circular muscle layer. The high pressures involved in burrowing demand the recruitment of the whole muscle system. The hind-gut ventilation stops when internal pressure is raised, although changes in the contained volume of the body wall do not appear to provide information leading to the maintenance of a fixed volume. Instead this control is probably excercised by the hind gut. An attempt is made to calculate the energy requirements of irrigation and ventilation and it is shown that these are small compared with the respiratory rate, indicating that the movement of large volumes of water for feeding purposes is not an extravagant way of obtaining food in terms of energy expenditure.
The Chemical Control of Feeding Behaviour in Cyphastrea Ocellina and in Some Other Hawaiian Corals*
Authors: Mariscal Richard N. , Lenhoff Howard M.
Published: April 2021

The feeding response of the Hawaiian coral Cyphastrea ocellina was elicited by alcoholic extracts of Artemia nauplii and of plankton. Chromatographic analysis of these extracts revealed that the imino acid proline was primarily responsible for the observed mouth opening and feeding behaviour. Somewhat less feeding activity was also caused by the reduced tripeptide glutathione. Analogues of these compounds, pipecolic acid and S-methyl glutathione, respectively, were as effective as the naturally occurring compounds. Some data are also presented for the feeding responses of two other Hawaiian corals, Pocillopora damicronis and Fungia scutaria.
The Morphology and Physiology of the Salamander Thyroid Gland
Authors: Uhlenhuth Eduard , Schwartzbach Saul
Published: April 2021

In the study of the physiology of the thyroid gland it is becoming more and more evident that the function of this organ is composed of a number of component activities. Only some of them are controlled by intrinsic mechanisms, while the most important of them, the release of the active secretion product of the gland from the follicles into the blood circulation is effected by stimulation through an extrinsic “releasing mechanism.” In warm-blooded animals the study of this releasing mechanism has received considerable attention, and although the question cannot by any means be considered a closed chapter of thyroid physiology, the work of O. A. Andersson(1), Leo Asher(2), Cannon and Fitz(3), L. B. Wilson(o) and others, is generally credited with having demonstrated that the autonomous nervous system is the path over which the stimuli of the releasing mechanism reach the thyroid in warm-blooded animals.

The senior author of this paper has been interested, for some time, in the physiology of the thyroid of cold-blooded animals, and especially in that aspect of it which concerns the nature of the releasing mechanism. This work has now entered an advanced stage and certain definite conclusions are possible. Although the results, together with the records, will be published in a series of more extensive articles, it seems desirable that the chief results be made accessible at once.
A Note on the Effect of Temperature on the Cardiac Rhythm of Certain Schizopods
Authors: Henderson Jean T.
Published: April 2021

It has been shown by Arrhenius that an expression analogous to the Van’t Hoff isochore can be applied to the velocity of chemical reactions, viz.: where K2, K1, are velocity constants corresponding to the absolute temperatures T2, T1 and μ is the energy of activation per gm. molecule. Arrhenius himself put forward the suggestion (1915) that this relation might be extended to the analysis of reactions which occur in animate systems. But as Heilbrunn has emphasised there is no a priori reason why an equation which defines a property of homogeneous systems, derived on the assumption that the system is homogeneous, should necessarily apply to systems of such heterogeneity as those which the biologist studies.
The Effect of Temperature Upon the Diffusion and Autolysis of the Metamorphic and Pigmentation Principles of the Pituitary Gland
Authors: Spaul E. A.
Published: April 2021

Diffusion and autolysis of the pigmentation and metamorphic principles of the pituitary proceed together after death of the animal. Rise in temperature increases the rate of diffusion and autolytic action. The presence of other principles and of autolytic products does not affect the response of the pigmentation principle but the activity of the metamorphic principle is reduced by diffused and autolytic products. As these products increase a point is reached when the presence of the metamorphic principle cannot be detected. Diffusion and autolysis are responsible in a large measure for the variations in the metamorphic and pigmentation results obtained by the administration of anterior and posterior lobe products.
The Absorption of Oxygen by Plaice Eggs
Authors: Burfield S. T.
Published: April 2021

The rate of oxygen absorption by plaice eggs, contained in a closed volume of sea water, falls when the eggs and water are allowed to remain relatively quiescent. This fall takes place even when a large volume of water is used. It has been shown that small changes in the partial pressure of dissolved oxygen do not appreciably affect the rate of absorption, so that this is not the factor concerned in the fall. The rate of oxygen absorption in a closed volume of sea water does not fall if the eggs be frequently moved. The removal of eggs to a closed volume of fresh sea water at the end of a period prevents the rate of absorption from falling during a second equal period. The removal of eggs to a closed volume of “used” sea water at the end of a period causes the rate of absorption to fall during a second equal period. The addition of urea in small quantities to the sea water has no effect on oxygen absorption. The addition of carbon dioxide to the sea water has a marked effect in lowering the rate of oxygen absorption, and the accumulation of excreted carbon dioxide is probably the factor causing the fall in absorption mentioned under paragraphs 1 and 5. This effect is possibly directly due to the alteration in the hydrogen ion concentration produced by the carbon dioxide. The Respiratory Quotient of young plaice eggs is about ·75.
The Influence of Age at Castration on the Size of Various Organs
Authors: Baker John R.
Published: April 2021

Male pigs were castrated at the ages of 50, 100 and 200 days. Others were not castrated. All were killed at 300 days. The weights of various sexual and endocrine organs at 300 days were determined, and a comparison instituted between pigs castrated at each age. The following results were obtained: (1) The vesicuiae seminales, bulbo-urethrals, and adrenals are smaller when castration is performed at 100 days than when it is performed at 200 days. There is much less difference (possibly none) according to whether castration is performed at 50 or 100 days. In uncastrated pigs the vesicuiae seminales and bulbourethrals are enormously larger even than those of pigs castrated as late as 200 days.(2) It is probable that some change occurs in these organs at about the age of 100 days, rendering them progressively more and more sensitive to the gonad hormone.(3) The thyroid, pineal, and pituitary are not significantly affected by time of castration. Body-weight also is not significantly affected.

A general discussion is given on the causes governing the size of the accessory sexual characters in mammals.
On the Influence of Intermittent Starvation on the Longevity of the Imaginal Stage of Drosophila Melanogaster
Authors: Kopeć Stefan
Published: April 2021

Under all the intensities of starvation investigated, the longevity of the imago stage of Drosophila was as a rule diminished. At the same time, flies which were starved for six hours out of every 24 and which were not deprived of water, lived at least as long as the controls. The longevity of flies increased in inverse proportion to the intensity of starvation. The longevity was greater in series in which the flies were never subjected to lack of water than in those in which intermittent starvation without water was practised. The injurious influence of longer, though less frequent fasting intervals was more pronounced than that of shorter though more frequent periods of inanition, both with or without administration of water. Starvation for six successive hours out of every 24 without water affected the flies most during the middle period of their life. The same effect was found during starvation for 12 successive hours out of every 24 when the flies were supplied with water. With lapse of time the flies became less resistant to the temporary absence of food.

Though the experiments performed did not give any clear results as to the supposed prolongation of life under the influence of intermittent starvation, some valuable hints for further study may be obtained from the observations recorded. The experiments on the influence of starvation for six hours out of every 24 with administration of drinking water must be repeated on a larger scale and it is intended to perform further experiments using a less intense degree of inanition. As with lapse of time the animals become less resistant to starvation, special experiments are also planned in which the flies will be intermittently starved until middle age and thereafter will be fed continuously.

This work was performed whilst holding a fellowship of the International Education Board (Rockefeller Foundation).
Comparative Studies of Accelerated Amphibian Metamorphosis
Authors: Spaul E. A.
Published: April 2021

The administration of active anterior lobe extracts in solution is not effective in producing precocious transformation of tadpoles. The rate of metamorphosis induced by injection of either thyroid or anterior pituitary depends within limits on the concentration of the initial dose. The time for completion with thyroid depends upon the total quantity given—a cumulative effect. The repetition of the stimulus given by a dose, the quantity per dose having maximum and minimum values, at suitable intervals decides the time of completion with anterior pituitary. Susceptibility of tadpoles to metamorphosis inducing factors increases with age. The effects produced by iodine in metamorphosis (mortality, reduction in size and shrinkage) agree more closely with those obtained in thyroid than pituitary treatment. There is a differential response of certain tissues to concentrations of the thyroid but not to anterior pituitary. Exposure of tadpoles to X-rays alters the susceptibility to factors accelerating metamorphosis. The effect increases with age. Alcohol and potassium cyanide lower the response to thyroid and anterior pituitary stimulation according to the concentration and the age of tadpoles. Normal rates of change are produced by thyroid and anterior pituitary in tadpoles under narcosis. The mortality is slightly higher with thyroid and depends on the concentration of the anaesthetic. Prolonged narcosis reduces the rate of change. Precocious metamorphosis is not found in tadpoles after feeding lipón the endostyle of Ciona intestinalis. The relation to iodine, quantitative and qualitative responses of tadpoles to treatment, and the differential tissue response serve to differentiate between the metamorphic principles of the thyroid and anterior pituitary.
The Effect of Hydrogen Peroxide on the Permeability of the Cell
Authors: Thomson David Landsborough
Published: April 2021

Szücs (1913) reported that hydrogen peroxide increased the permeability of the living cell. Following up a previous observation [Bokorny, 1886], he found that if threads of Spirogyra were treated first with hydrogen peroxide and then with ferrous sulphate solutions, a dark precipitate appeared within the cells. He concluded that the hydrogen peroxide had so increased the permeability of the cell that the ferrous ions were able to enter and form a dark iron-tannin compound. It was also found that hydrogen peroxide increased the permeability of the cell to various dyes. In view of the ever-increasing importance of the rôle assigned to hydrogen peroxide in cell metabolism it seemed worth while to re-open this question. As Szücs gives no details of his experiments, an exact repetition was impossible.
The Action of Potassium on Muscle-Preparations from Invertebrates
Authors: Wells George P.
Published: April 2021

When the crop of Aplysia is bathed by a solution containing 0.011 M KC1, tonic contraction and inhibition of the rhythmic movements result if potassium is either withdrawn or added in excess. The action of potassium on tone in the Aplysia crop is independent of the calcium concentration. Rb, Cs and NH4 act like potassium on the Aplysia crop, but Li does not. Rb is about twice as active, Cs about one-half as active, and NH4 about one-fifth as active as potassium. The changes of tone seen in the Helix crop when the potassium concentration is varied are identical with those seen in vertebrate plain muscle under like conditions. Addition of a little potassium to the heart of Maia perfused with a potassium-free fluid causes a drop of tone. High concentrations of potassium have two opposed effects, a contracting action and a secondary depressing action. The action of potassium on the striped muscle of the Maia heart is essentially like its action on molluscan or vertebrate plain muscle.
New Developments in Ovarian Dynamics and the Law of Follicular Constancy
Authors: Lipschutz Alexander
Published: April 2021

It has been shown in previous papers in this Journal (1, 2) that very characteristic phenomena take place in an ovarian fragment if the total ovarian mass is reduced by partial castration. There is an hypertrophy of the ovarian fragment and a greatly reduced number of young ova, while large follicles and often follicular cysts are found in the fragment. The diminution of the number of primary follicles was explained by assuming that they had been absorbed during follicular development. These conclusions, together with those of Arai, Hammond and Asdell in mammals, of Hartman in the opossum, of Pearl and Schoppe in the fowl, were summarised in “the law of follicular constancy,” which means that the number of ova entering into follicular development, the rhythm of follicular development and the degree which is attained by follicular development are constant and are controlled by somatic factors outside the ovary. The latter supposition was a further development of the theories of Heape, Sand (3), Hammond and Marshall (4). In further experiments on cats (2) it was shown that the diminution of the number of young ova in an ovarian fragment and the formation of follicular cysts do not depend upon the operative interference itself, as there is no diminution of young ova and there are no follicular cysts in ovarian fragments when the total ovarian mass is not diminished. Later, further experimental evidence (5) concerning the law of follicular constancy was obtained by grafting a third ovary into normal guinea-pigs. No corpus luteum was ever found in such ovarian grafts when examined several months later, though corpora lutea are always present in ovarian grafts in previously castrated females.
The Pigmentary Effector System V. the Nervous Control of Excitement Pallor in Reptiles
Authors: Hogben Lancelot T. , Mirvish Louis
Published: April 2021

The chromatic responses of the chameleon have excited curiosity from the earliest times. They were known to Aristotle, who wrote concerning them: “the change in the colour of its skin takes place when it is filled with air. It can acquire either a black colour like that of a crocodile, or ochreous like that of a lizard, or spotted with black like the panther; for the eyes also change like the rest of the body, and so does the tail1” (Book II, History of Animals).
The Effect of Dilution on the Activity of Spermatozoa
Authors: Gray J.
Published: April 2021

As long as the seminal fluid of a ripe sea-urchin remains undiluted, little or no movement occurs on the part of the spermatozoa. If, however, a small drop of this fluid comes into contact with sea-water, the cells at the surface of the drop at once become intensely active and eventually the whole of the spermatozoa exhibit lively movement. There appear to be at least four possible causes for this immediate activation in sea-water : (i) The failure to move in the testicular fluid may be due to the presence of an inhibitory substance in the medium, so that on dilution this substance is removed and the spermatozoa are activated, (ii) Sea-water may contain some element, absent from the testicular medium, which is necessary for movement. (iii) The viscous resistance of the testicular fluid may be too high for active movement, (iv) Each spermatozoon may exert some form of inhibition on the movements of its neighbours. The following experiments were designed to test these hypotheses.
The Iodine Content of the Thyroid of the Fowl with Reference to Age and Sex
Authors: Chaudhuri A. C.
Published: April 2021

The iodine content of the thyroid of the sexually immature male fowl is lower than that of the thyroid of the sexually mature. The increase in iodine content is coincident with the attainment of sexual maturity as estimated by the histological picture of the testis. In the case of the material used there was no indication of a sex dimorphism in the matter of iodine content. The average percentage of iodine content of the thyroid of the bird is significantly higher than that of the mammal.
The Length of the Oestrous Cycle in the Unmated Normal Mouse: Records of One Thousand Cycles
Authors: Parkes A. S.
Published: April 2021

Analysis of the records of 1000 oestrous cycles in the normal unmated mouse give the following results :

Mean length of whole cycle = 6 ·213 ± 0 ·0554 days.

Mean length of dioestrus (including meta-oestrus) = 3 ·719 ± 0 ·0502 days.

Mean length of oestrus (including pro-oestrus) = 2 ·494 ± 0 ·0223 days.
Neuromuscular Properties of Mesenteries from the Sea-Anemone Metridium
Authors: Robson E. A. , Josephson R. K.
Published: April 2021

A method is described for a simultaneous electrical and mechanical recording from isolated mesenteries of the sea-anemone Metridium senile (L.). The retractor muscle gives quick and slow contractions. Shock intervals of 0·15–2 sec. produce facilitated twitches on all stimuli after the first, usually followed by a slow contraction. Trains of stimuli at lower frequencies are followed by slow contractions only. Slow contractions may also arise spontaneously. Two types of potential were found using external suction electrodes, provisionally interpreted as nerve-net impulses and muscle action potentials. The first is an all-or-none compound pulse, whose brief components summate (1–3 msec., height up to 0·4 mV.). Conduction speed in an expanded anemone would be 70–120 cm./sec. at 14–16 °C., corresponding to that of the through-conduction system. The second always precedes a twitch and is a smooth, graded potential lasting 50–100 msec. Its size, up to 1·2 mV., is inversely related to stimulus interval, but unlike the quick mechanical rseponse it shows but slight initial facilitation. A muscle potential follows a nerve-net impulse and is propagated at the same speed. The refractory period of the nerve-net probably exceeds that of the muscle. Potentials showing similar features have been recorded from the oral disk and tentacles. These results support the suggestion that the sites of facilitation and initiation of contractions are neuromuscular junctions throughout the retractor muscle. Quick contractions are co-ordinated by the nerve-net, whereas it is possible that slow contractions, however initiated, may at least in part be propagated in the muscle itself.
Excitation and Habituation of the Crayfish Escape Reflex: The Depolarizing Response in Lateral Giant Fibres of the Isolated Abdomen
Authors: Krasne Franklin B.
Published: April 2021

Crayfish commonly evade capture by darting backwards when one tries to pick them up or otherwise disturbs them. They do this by sharply flexing the abdomen, the tail fan acting as a paddle; at the same time they streamline themselves by thrusting their appendages forward.
Polyneuronal Innervation of the Fast Muscles of the Marine Teleost Cottus Scorpius L
Authors: Hudson Richard C. L.
Published: April 2021

Histological and electrophysiological studies of the spinal nerves, nerve roots and muscles of the abdominal wall of the marine teleost Cottus scorpius have been undertaken to determine the extent and nature of polyneuronal innervation of the fast muscles. Spinal nerves at proximal and distal levels, and the dorsal roots, contain axons in a single mixed population with a mean diameter of 2–4 μm., while the ventral roots contain axons in two diameter classes with means at 4–6 and 12–14 μm. Between 8 and 22 distributed nerve terminations were counted on fifty-two teased intact single muscle fibres stained for acetylcholinesterase activity. The average distance between the terminals is 0·64 mm. (range 0·094–2·050 mm.). The compound action potential of the nerve comprises two principal peaks with conduction velocities of 17·0–23·8 m./sec. and 1·5–12·2 m./sec. at 10–12°C. Fast muscle fibres gave two types of electrical response-all-or-none spike potentials that are propagated with a conduction velocity of c. 1·1 m./sec. at 10–12° C., and quantized distributed junction potentials. The electrical properties of the nerves and roots suggest that the fast muscles are innervated by a single class of fast axons and possibly by a few slow axons. Simultaneous recordings of nerve and muscle activities were made at different stimulus intensities. In all cases muscle responses were correlated with the first peak of the compound action potential, and appeared with the same or only slightly different latencies. Each muscle fibre is shown electrophysiologically to be polyneuronally innervated by 2–5 axons from a single spinal nerve, and to receive a similar axonic complement from each of four spinal nerves. Polyneuronal innervation of the muscle fibres by 8–22 different axons in the absence of multiterminal innervation is postulated.
Measurements of the Osmotic Pressure in the Habitat of Polymorphus Minutus (Acanthocephala) in the Intensine of Domestic Ducks
Authors: Crompton D. W. T. , Edmonds S. J.
Published: April 2021

The osmotic pressure in the environment of Polymorphus minutus in the alimentary tract of ducks has been measured. Samples of intestinal contents were collected through cannulae inserted at known positions into the parasite’ s environment. Samples were recovered from two healthy living ducks, without inducing anaesthesia, from points at 60% and 80% of the distance along the intestine, and from ten freshly killed ducks at a point 70 % of the distance along the intestine. The mean osmotic pressures at 60%, 70% and 80% of the distance along the intestine were found to be 170·5, 171·6 and 178·2 mM-NaCl/1. respectively and the variance was found to be 154·84, 84·41 and 30·13 for the three positions respectively. It is postulated that the greater fluctuations in osmotic pressure at the anterior end of the environment may be responsible for the posterior migration of the parasite during the course of the infection. The method here described for investigating osmoregulation in P. minutus may be of general application for studying aspects of the biology of small intestinal helminths in vivo.
The Central Nervous Control of Complex Movements in the Uropods of Crayfish
Authors: Larimer J. L. , Kennedy D.
Published: April 2021

The control of postural uropod muscles in the crayfish has been investigated by stimulating ‘command’ interneurones isolated from central connectives. Reciprocity is preserved between exciters and inhibitors innervating the same muscle, and between motor axons serving antagonists. The control of combined movements, involving groups of muscles that are neither synergists nor antagonists, was analysed by simultaneous recording. Most command fibres affected several different motor pathways, and different command fibres produced different combinations of output. It is concluded that quite complex movements may be encoded in the connexions of a single central element. In several instances it was shown unequivocally that single central neurones were responsible for releasing the motor output. One identified command neurone produces a stereotyped, rhythmic pattern of activity in several motor pathways. This effect did not depend upon afferent feedback for its form or frequency. Command interneurones often produce asymmetrical responses in the appendages of the two sides. Some of these make connexions only to the ipsilateral motor neurones, others only to contralateral ones, and most make differential connexions on the two sides.
Sensory and Motor Interaction in the Locomotor Reflexes of Crabs
Authors: Evoy W. H. , Cohen M. J.
Published: April 2021

Proprioceptive reflexes involved in control of the mero-carpopodite (MC) joint in walking legs of Cancer magister are mediated by four groups of sensory cells: two cell groups (myochordotonal organs), located proximally in the leg segment, which are associated with a receptor muscle and come under efferent control, and two cell groups (MC organs) located distally which signal joint position and movement but are independent of efferent control. Resistance reflexes, which oppose passive movements of the joint, are evoked by both types of proprioceptive organs. Reflexes evoked by the MC organs are maximally effective at the extremes of joint position. Reciprocal inhibition of antagonistic muscle groups appears to occur entirely at synapses within the central nervous system. Efferent control of the receptor muscle comes under the influence of both the myochordotonal and MC organs. The reflexes evoked by the MC organs on the receptor muscles are similar to those which impinge on the main flexor. The myochordotonal organ excites the receptor muscle on joint movements away from the rest position. Interaction of input from the two types of sense organs provides the system with a dynamically determined reference point for the basic postural position. This may be altered by efferent control of the receptor muscle. Reflexes evoked by both types of proprioceptive organ spread to the other walking legs, but are more labile than reflexes to the same leg.