bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Supply of Oxygen to the Active Flight Muscles of Some Large Beetles
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
Measurements of the wing-beat frequency, wing-stroke amplitude and stroke plane and of abdominal ventilation have been made during the tethered flight of twenty-six species of beetles belonging to five families, mainly in Uganda. Abdominal ventilation is weak or absent in all species of Cerambycidae, Elateridae and Anthribidae examined in flight. The tracheal system in these families is characterized by the complete absence of air sacs, and in larger species by the presence of four giant trunks running through the metathorax between spiracles 2 and 3 and forming the primary supply to the flight muscles. Abdominal ventilation is strong during the flight of all species over o·6 g. in weight of the Scarabaeidae and Buprestidae which were examined. Their tracheal systems contain an abundance of air sacs while giant trunks are absent. Measurements of the thoracic volume changes which accompany each wing beat show that the amount of air which can be pumped in this way increases in larger Cerambycidae per second per gram as compared with small species. Large Cerambycidae pump more per gram than Scarabaeidae of comparable size. During the flight of the cerambycid Petrognatha the thoracic pump exchanges 540 μ1. air/sec./g. Its action is mainly on the compressible secondary tracheae. In a wind speed of 5 m./sec. 1050 μ1. air/sec./g. are driven through the four giant trunks, entering through spiracle 2 and leaving from spiracle 3. The trunks are stout-walled and probably unaffected by the thoracic pump.
The Mobilization of the Calcium Carbonate Deposits in the Endolymphatic Sacs of Metamorphosing Frogs
Authors: Pilkington J. B. , Simkiss K. 
Published: April 2021

ABSTRACT
Tadpoles of Rana temporaria have been reared in solutions of high and low pH with and without calcium. Methods have been devised for analysing calcium, carbonate and phosphate in individual tadpoles. From these analyses it is possible to determine the distribution of calcium salts between the endolymphatic sacs and the skeleton throughout metamorphosis. A system has been devised for correlating biochemical data with the morphological changes occurring during metamorphosis by means of a scale of ‘developmental days’. The resorption of the endolymphatic deposits is not influenced by the acidity of the environmental solution. Tadpoles reared in solutions containing added calcium had at any one stage in metamorphosis a larger reserve of endolymphatic calcium and a better ossified skeleton than the other tadpoles. During metamorphic climax, when the tadpoles do not feed, the calcareous material in the endolymphatic sac is resorbed to provide calcium for the ossification of the skeleton and to make good any renal loss of calcium. The resorption of endolymphatic calcium carbonate occurs in all tadpoles during metamorphic climax irrespective of the level of calcium in the environmental water. The otoliths do not appear to be resorbed and the spinal portion of the deposits in the endolymphatic sacs may be more labile than those in the cranial regions.
Maternal Induction of Diapause in the Larva of Lucilia Caesar L. (Diptera: Calliphoridae)
Authors: Ring R. A. 
Published: April 2021

ABSTRACT
The seasonal pattern of diapause incidence in Lucilia caesar L. shows that diapause in the 3rd-instar larvae of field-captured females increases rapidly during the month of July. By rearing and testing all larvae under standard laboratory conditions confirmation has been given to the hypothesis that this sudden increase, which occurs soon after the summer solstice, is due to a maternal influence. It has been shown that photoperiod is the most important factor controlling this maternal influence, with temperature playing a modifying role in the photoperiodic response. Females do not respond to the intrinsic rate of change in the photoperiod, but to the absolute levels of the light/dark phases. Long photoperiods (20 hr.) tend to avert, and short ones (12 hr.) tend to induce, larval diapause. Thus L. caesar is another example of a ‘long-day’ species as described by Lees (1955). Under laboratory conditions there is a time lag of 8-10 days before a change in the absolute length of the photoperiod acting on the mother reflects its diapause influencing effect on the larvae. Maternal ageing produces an increase in larval diapause incidence after 6-10 weeks. It is not yet known whether or not the maternal influence is hormonal in character.
Further Studies on the Electrophysiological Anatomy of the Left and Right Giant Cells in Aplysia
Authors: Hughes G. M. 
Published: April 2021

ABSTRACT
Electrophysiological studies on cells of Aplysia central ganglia have become of general interest in recent years and have developed from work on the nature of integrative mechanisms (Arvanitaki & Chalazonitis, 1959; Tauc, 1955; Tauc & Hughes, 1963) to investigations of plastic change at a cellular level (Bruner & Tauc, 1966; Kandel & Tauc, 1965). Earlier work showed the range of phenomena found in a variety of cells, particularly in the abdominal ganglia, but research has now become more concentrated on certain cells which are readily identifiable in all preparations (Strumwasser, 1965 ; Hughes & Tauc, 1961 ; Kandel & Tauc, 1965). Of these cells, the large cell in the right upper quadrant, which is often called the giant cell, or right giant cell (RGC), has been used a great deal in studies on the basic phenomena of spike initiation in molluscan cells (Tauc, 1962). The anatomy of this cell was shown to be quite complex as a result of electrophysiological studies (Hughes & Tauc, 1963) which also revealed the presence of a comparable cell (LGC) on the left side of the C.N.S. Because of similarities in the general pattern of branching of these cells, they were considered homologous.
Relationships Between Photoperiodism and Circadian Rhythms of Activity in the House Finch
Authors: Hamner W. M. , Enright J. T. 
Published: April 2021

ABSTRACT
The Büuning hypothesis proposes that many rhythmic physiological processes, including photoperiodic responsiveness, are all based upon a single, endogenous circadian time-measuring system (‘die physiologische Uhr’). We have attempted to test this hypothesis by examining correlations between the circadian waking-sleeping rhythm of the house finch (Carpodacus mexicanus), and the circadian rhythm of sensitivity to light, which underlies the photoperiodic testicular responses of this species. Experimental techniques included (1) comparisons of locomotor activity patterns induced by specific non-daily light cycles which stimulate gametogenesis (LD 6:30 and 6:54) with those induced by other cycles which are non-inductive (LD 6:18, 6:42 and 6:66); (2) comparisons of gametogenesis resulting from light cycles which produce large phase-lead in the activity rhythms and thereby result in photic stimulation late in the ‘subjective day’ (LD 6:20 and 3:23) with results from similar cycles which cause no phase lead (LD6:i6 and 3:19); and (3) comparisons of gametogenesis under free-running (unsynchronized) conditions in which a 6 hr. stimulus was intermittently administered early in the ‘subjective day’, with other treatments in which the same stimulus was administered late in the ‘subjective day’. In all experimental series, when only group responses are considered, there were clear and strong correlations between testicular growth and the patterns observed in locomotor activity. The nature of the large intra-group variability, however, convinces us that the Bünning hypothesis, as here interpreted, is inadequate to account for all the results. Either the two circadian rhythms may be independent, similar systems; or, if there is a single ‘master clock’, the two manifestations of this timing system are apparently not phase-locked under artificial laboratory conditions. It is not clear to us how these two alternatives are experimentally distinguishable.
The Roles of Sodium Transport and Anion Permeability in Generating Transepithelial Potential Differences in Larval Salamanders*
Authors: Dietz Thomas H. , Kirschner Leonard B. , Porter David 
Published: April 2021

ABSTRACT
Recent investigation has shown that the fully aquatic, larval form of the salamander Ambystoma tigrinum handles osmotic and ionic regulatory problems as do other fresh water and semiterrestrial animals. Faced with osmotic water entry from a hypotonic environment, it excretes a dilute urine to remain in water balance. Uptake of NaCl from artificial-pond water occurs at the rate of about 1μ-equiv. (10 g.)−1hr.−1. This maintains an ionic steady state by compensating for losses in the urine and by diffusion across the skin and gills (Alvarado, 1962; Alvarado & Kirschner, 1963). Animals in a steady state in pond water ([NaCl] = 1·2 mM/1.) have a potential difference across the body surface of 10–20 mV., body fluids positive to the external solution. Nothing is known about the mechanism generating electrical asymmetry in these animals.
Changes in Blood Pressure in the Rainbow Trout During Hypoxia
Authors: Holeton G. F. , Randall D. J. 
Published: April 2021

ABSTRACT
Methods for cannulating the ventral aorta of the trout, which permit the measurement of blood pressure in the unanaesthetized, unrestrained, intact fish are described. Rate and amplitude of breathing and blood pressure in the dorsal and ventral aortae increase during hypoxia. These changes are associated with a marked bradycardia. There are increases in vascular resistance to blood flow in both respiratory and systemic circulations during hypoxia. Post hypoxia is associated with large increases in ventral aortic and dorsal aortic pressures.
The Exchange of Oxygen and Carbon Dioxide Across the Gills of Rainbow Trout
Authors: Randall D. J. , Holeton G. F. , Stevens E. Don 
Published: April 2021

ABSTRACT
The effectiveness of oxygen uptake by the blood of rainbow trout (Salmo gairdneri) approaches 100%, whereas that for the removal of oxygen from water was only 11-30%. Most of the carbon dioxide is removed from the blood as it passes through the gills, but the effectiveness of carbon dioxide uptake by water is very low, because of the high capacity of water for carbon dioxide compared with oxygen. Moderate exercise had little effect on the effectiveness of gas exchange across the gills. The increased oxygen uptake was facilitated by an increase in the transfer factor of the gills for oxygen. There were small increases in the capacity-rate ratio of blood to water at the gills during moderate exercise. Hypoxia resulted in a marked decrease in the effectiveness of oxygen uptake by the blood, but had little effect on oxygen removal from the water. Gas exchange was facilitated during hypoxia by an increase in transfer factor of the gills, but hindered by an increasing capacity-rate ratio of blood to water at the gills. Gas exchange in an aquatic environment was compared with that in an aerial environment.
Axonal Function and Ionic Regulation in the Central Nervous System of a Phytophagous Insect (Carausius Morosus)
Authors: Treherne J. E. , Maddrell S. H. P. 
Published: April 2021

ABSTRACT
Experiments using intracellular and extracellular recording techniques indicate that, despite the specialized ionic composition of the haemolymph, the axons in the nerve cord of Carausius are conventional in that the action current is largely carried by sodium ions. This effect is achieved by an appreciable regulation of the concentrations of inorganic ions in the extracellular fluid bathing the axon surfaces. The extra-axonal regulation does not appear to result from any significant restriction in the accessibility of cations to the general extracellular system, but from a local regulation which appears to maintain a relatively high concentration of sodium ions at the axon surfaces. It is suggested that such a regulation may be achieved by an extrusion of sodium ions from the glial cells into the restricted extra-axonal spaces demonstrated in the electron micrographs of this preparation.
Extraretinal Pigmentation and Colour Discrimination
Authors: Volpe P. , Carfagna M. , Lorenzo M. Di 
Published: April 2021

ABSTRACT
The hypothesis that the choice of substrate colour for oviposition may vary preferentially according to the type of eye pigment has been confirmed by experiments on three phenotypes of D. melanogaster, the normal or wild type, the vermilion mutant, having no homochrome, and the brown mutant, lacking pteridine. The results can be summarized thus : (a) no preferential selection on the part of the wild phenotype ; (b) unambiguous preference by vermilion for blue, a preference less clearly marked for yellow, with green rejected ; and (c) clear preference by the brown mutant for green, with rejection of blue. Choice of colour during oviposition was found to be different from that expressed by phototactic response to certain monochromatic lights, as reported some years ago. The probable biological significance of such behaviour in functions which are physiologically distinct is also discussed.
Bioelectric Regulation of Tentacle Movement in a Dinoflagellate
Authors: Eckert Roger , Sibaoka Takao 
Published: April 2021

ABSTRACT
Recurring extensions and flexions of the food-gathering tentacle of Noctiluca miliaris occur spontaneously. Identical movements can be evoked by appropriate electrical stimulation. Spontaneous recurring potential wave forms (TRPs) were recorded from the vacuole of the luminescent form of Noctiluca during movements of the tentacle. The basic TRP wave form consists of a characteristic negative-going spike which arises at −20 to −30 mV. from the slowly redeveloping negativity of a pre-spike depolarization, and is followed by a quasi-stable post-spike d.c. level of relative vacuolar negativity (−45 to −60 mV.). The TRP complex, similar in shape to that which occurs spontaneously, follows an intracellularly applied current pulse of either polarity if the vacuolar potential is at the post-spike level. The duration of the evoked pre-spike wave is related to the current intensity and duration. During the pre-spike state outward current is ineffective, although a TR spike occurs in response to inward current. The TRP is distinct in its behaviour and wave form from the flash-triggering potential, which can be evoked in the same cell, even though both exhibit all-or-none spikes. Simultaneous recordings of intracellular potentials and movements of the tentacle showed a consistent temporal relationship between potential changes and subsequent movement. Extension of the tentacle begins 1–2 sec. after the spike and flexion begins within i sec. after beginning of the pre-spike wave. Tentacle movement ceased in Ca-free sea water even though the cyclic potential changes continued normally. Electron micrographs of the tentacle showed longitudinal aggregations of microtubules near the outer surface of the peripheral cytoplasm. It is proposed that contraction of these microtubules is the immediate cause of tentacle movements.
Sodium, Chloride and Water Balance of the Intertidal Teleost, Xiphister Atropurpureus
Authors: Evans David H. 
Published: April 2021

ABSTRACT
The effluxes of 22Na, 36Cl and tritiated water from the euryhaline teleost, Xiphister atropurpureus were determined in 100% sea water (480 mM-Na/kg.) and 10% sea water. Only the flux of sodium in 100% sea water contained an exchange diffusion component. The relative impermeability of Xiphister is shown by its low fluxes of sodium, chloride and water in both salinities. In 10% sea water the permeability to sodium declined while the permeability to chloride and water remained at sea water levels. In both salinities diffusion and active transport are the major components of the sodium and chloride balance of Xiphister.
Discrimination, Previous Experience and Substrate Selection by the Amphipod Corophium
Authors: Meadows P. S. 
Published: April 2021

ABSTRACT
Populations contain no animals that are consistently less discriminating than others in their choice of substrates. Previous experience in atypical substrates does not alter preferences for typical substrates. Animals live slightly longer in very fine-grained substrates than in coarser ones. Their growth rates do not differ over a range of particle sizes. Animals select the smaller grains in a substrate to build their tubes with.
The Water Repellency and Feather Structure of Cormorants, Phalacrocoracidae
Authors: Rijke A. M. 
Published: April 2021

ABSTRACT
The water-repellency of the feathers of ducks is greatly increased by a structural feature which can be expressed in terms of diameter and spacing of the barbs and barbules. This structural parameter is smaller for cormorant’s feathers and causes a lesser extent of water repellency. The resulting wetness of the feathers is the proximate cause of the cormorant’s characteristic habit of wing-spreading.
A Theoretical Treatment of the Reflexion of Light by Multilayer Structures
Authors: Huxley A. F. 
Published: April 2021

ABSTRACT
A convenient method is presented for calculating the reflectance of a stack of dielectric layers consisting of a series of identical repeats of any particular sequence of layers. The method is closely related to that published by Lord Rayleigh in 1917. In this method, two quadratic equations are formed from the thicknesses and refractive indices of the layers composing a single repeat unit. The reflectance is obtained by substituting the solutions of these equations into an explicit formula. Particularly simple formulae result for the case of a stack of p plates, optical thickness λϕ/2π, uniformly spaced in an infinite medium with spaces of the same optical thickness. If r is the amplitude reflexion coefficient at a single interface, the reflectance of the whole stack is as follows : when cos2ϕ &lt; r2, where when cos2ϕ &gt; r2, where when the number of repeats in the stack is large (p → ∞), reflexion is complete so long as cos2ϕ &lt; r2. Outside this range the reflectance is . These results are extended to cover: (a) unequal optical thicknesses in plates and spaces; (b) oblique incidence; (c) layers of materials of other refractive indices above and below the stack itself; and (d) stacks consisting of repeats of more complex units.
Seasonal Temperature Influence on Vagal Control of Diving Bradycardia in the Frog (Rana pipiens)
Authors: Lund Gordon F. , Dingle Hugh 
Published: April 2021

ABSTRACT
The influences of asphyxia, temperature, and restraint on diving bradycardia in amphibia have been considered. In restrained diving frogs two forms of bradycardia were distinguised on the bases of rate of attainment, control, and degree of hear-rate reduction. A rapidly attained immersion bradycardia could be eliminated by atropine or bilateral vagotomy and was thus similar to that of other vertebrates. A slowly attained asphyxiant bradycardia, independent of vagal influences, also occured but was less pronounced. Electrical stimulation experiments were conducted in September to determine the influence of temperature on vagale inhibition of the heart. With decreasing temperature partial block of vagal inhibition occurred at about 11° C., and complete block occured at 7-8°C.; on rewarming, partial block returned around 11-12°C., and complete vagal inhibition of the heart was re-established at about 14° C. Though both forms of bradycardia may occur in any one dive, the form predominating was dependent on temperature and season. A seasonal variability regarding the temerature at which vagal inhibition of the heart can occur has been suggested. A pronounced diving bradycardia, either slowly or rapidly attained, probably does not occur in unrestrained frogs under normal environmental conditions.
Effect of Adrenergic Drugs on the Lantern of the Larval Photuris Firefly
Authors: Carlson Albert D. 
Published: April 2021

ABSTRACT
A number of adrenergic drugs were tested for their ability to induce luminescence in the extirpated lantern of the firefly larva. The drugs produce sigmoid doseresponse curves characteristic of drug-receptor interactions when drug concentration is plotted against either maximum intensity or maximum rate of intensity rise. Amphetamine and saline of high potassium concentration induce intense luminescence in freshly extirpated lanterns but act only weakly or not at all in lanterns suffering from treatment by reserpine injection 48 hr. previously. No significant difference in response to norepinephrine was observed in lanterns immersed in standard saline, 0.32 M sucrose, 0.16 M choline chloride or 0.16 M-NaCl2 but 0.107 M-CaCl2 considerably slowed the response. Some generalizations concerning structural character and effectiveness in inducing luminescence were made by comparing the drugs tested. It was not possible to describe the mode of action of the drugs. The observation, however, that solutions lacking sodium and potassium did not significantly alter the response was felt to argue against the action of the adrenergic drugs in affecting ion movement across the photocyte membrane.
The Labial Gland: A Salt-Secreting Organ of Saturniid Moths
Authors: Kafatos Fotis C. 
Published: April 2021

ABSTRACTThe labial gland of adult saturniids produces a voluminous liquid at about the time of ecdysis, in response to either confinement of the moth or physostigmine injection. This liquid normally facilitates escape from the cocoon. During secretion the gland accumulates K+ and HCOS−from the blood, and Rb+ if it is available, but excludes rather efficiently Na+, Li+, Sr2+, Ca2+, Mg2+, phosphate and other small molecular weight components of blood. Cl− is approximately equally distributed in blood and secretion. The pH of the secretion is approximately 8·5, as compared with 6·5 for blood. The secretion is in osmotic equilibrium with blood, even after alteration of blood osmotic pressure by injection of hypertonic or hypotonic solutions. For both Cl− and Na+ the rate of entry into the secretion is proportional to concentration in blood; i.e. the efficiency of exclusion is characteristic for each ion, within a wide range of blood concentrations. Secretion is accompanied by a potential difference across the secretory cell (ca. + 25 mV. lumen positive). Secretion is abolished by dinitrophenol, but not by ouabain or acetazoleimide. The results are best explained in terms of a respiration-mediated active accumulation of blood K+, in exchange for H+, in the basal region of the cells; this is presumably followed by release of the K+ into the lumen, with concomitant reabsorption of H+ from the secretion. The alkaline secretion then traps blood CO2 by converting it to HCO3−. Water follows osmotically, and other ions enter passively, at a rate determined by the corresponding permeability of the cells.
Effects of Sub-Lethal High Temperature on An Insect, Rhodnius prolixus (Stål.)
Authors: Okasha A. Y. K. 
Published: April 2021

ABSTRACT
In Rhodnius larvae, when moulting is delayed under normal temperature conditions by exposure to high temperature directly after feeding, the brain is needed for a period longer than normal to complete development, i.e. the critical period is postponed. This is associated with a delay in the activation of the thoracic glands and in the mitotic activity in the epidermis. It is suggested that high temperature may act directly on the brain thus inhibiting the secretion of its hormone, although other possibilities are also discussed. The process of wound heating at normal and high temperatures is compared. Injury of the integument results in the ‘activation’ of the epidermal cells and their migration towards the wound. Consequently, a zone of sparse cells is formed which persists at high temperature, since cell division in the epidermis is inhibited. The bearing of the inhibition of cell division on the cessation of moulting at high temperature, even in the presence of the moulting hormone, is discussed.