bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Balance in the Firebrat, Thermobia Domestica (Packard). Exchanges of Water with the Atmosphere
Authors: Noble-Nesbitt J. 
Published: April 2021

ABSTRACT
Uptake of water from the atmosphere by previously desiccated, starved Thermobia domestica is related to the % relative humidity, and occurs in and above 63% R.H. between 17 and 37 ° C. Losses occur in and below 43% R.H. Uptake is often, though not invariably, arrested during even brief periods of locomotor activity. Recovery from desiccation proceeds to the same level of body-water content in all humidities above the ‘critical’ value. Equilibrium is reached more rapidly in the higher temperatures and humidities. The equilibrium level attained is the same as that found in control insects, and it does not change when the insect is transferred from one high humidity to another. During periods of relatively large dry-weight losses, a greater proportion of water is retained in the body, providing some volume regulation. The living insect restricts its water loss in low humidities by means of a permeability barrier which is disrupted during uptake in high humidities and is progressively lost on death. This restriction is not dependent upon the continued activity of the uptake mechanism.
Central Neuronal Response to the Activation of Osmoreceptors in the Osphradium of Aplysia
Authors: Stinnakre J. , Tauc L. 
Published: April 2021

ABSTRACT
The physiology of osphradium (the pallial organ situated near the branchiae in most mollusca with the exception of the higher cephalopods) is poorly known. Since the work of Copeland (1918) on Busycon canaliculatum, it has been generally accepted that the osphradium serves a chemoreceptive function. This conception has been shared by Henschel (1932), Brock (1936), Brown & Noble (1960)Michelson (1960) and Wolper (1950); all of whom reached this conclusion by means of experiments in which behavioural responses to a variety of stimuli were observed before and after the removal of the osphradium.
Effects of γ-Aminobutyric Acid and Picrotoxin on the Permeability of the Longitudinal Muscle of the Earthworm to Various Anions
Authors: Ito Y. , Kuriyama H. , Tashiro N. 
Published: April 2021

ABSTRACT
The effects of GABA and picrotoxin on the input resistance of the muscle of the earthworm, Pheretima communissima, in Ringer solution and in solutions containing various foreign anions were observed.
Substitution of Cl− by I− and Br− reduced the input resistance and hyperpolarized the membrane. Although anions larger than chloride in hydrated size increased the input resistance, no change of the membrane potential was observed. GABA reduced the input resistance of the membrane and picrotoxin increased it in Ringer solution. The dose-response curve for the changes of the input resistance under various concentrations of GABA shifted parallel-wise under treatment with picrotoxin. In the presence of foreign anions which had larger hydration size than Br−, GABA reduced the input resistance. Picrotoxin did not, however, increase the input resistance when the solutions contained anions of smaller hydration size than C1O4−. Reversal potential levels for the miniature inhibitory junction potential in various concentrations of chloride were measured. The change of the reversal potential levels produced by a tenfold change of chloride concentration was 25 mV.
Two Slow Conduction Systems in the Sea Anemone Calliactis Parasitica
Authors: McFarlane I. D. 
Published: April 2021

ABSTRACT
Suction electrodes record electrical activity associated with three conduction systems in the sea anemone Calliactis parasitica. The two slow systems (SS1 and SS2) are previously undescribed. The third system is the through-conduction system. Evidence is given that the SS1 and SS2 are located in the ectoderm and endoderm respectively. The conductile elements have not been identified. The conduction velocity of the SS1 is 4·4–14·6 cm./sec. at n° C. and is highest in the oral disk. The SS2 velocity is 3·0–5·3 cm./sec. Both slow systems show a marked increase in response delay on repetitive stimulation and fail at stimulation frequencies higher than one shock/3 sec.
Co-Ordination of Pedal-Disk Detachment in the Sea Anemone Calliactis Parasitica
Authors: McFarlane I. D. 
Published: April 2021

ABSTRACT
Electrical activity has been recorded from the sphincter region of Calliactis parasitica during the behavioural sequence in which the anemone detaches from the substrate and attaches to a Buccinum shell. The ectodermal slow-conduction system (SS1) fires repetitively, the majority of observed pulses occurring in the period prior to detachment (a typical example is 25 SS1 pulses at an average frequency of 1 pulse/ 7 sec.). Shell-tentacle contact is essential for stimulation of SS1 activity. Mechanical stimulation of the column excites the SS1, and 30 stimuli at a frequency of about one shock/5 sec. give pedal disk detachment. Electrical stimulation of the ectoderm excites the SS1 and about 30 stimuli at frequencies between one shock/3 sec. and one shock/9 sec. produce detachment. Detachment and the SS1 have an identical stimulus threshold. It is concluded that detachment is co-ordinated by the SS1.
The Permeability of the Shell of the Egg of Teleogryllus Commodus Measured with the Aid of Tritiated Water
Authors: Browning T. O. 
Published: April 2021

ABSTRACT
Eggs of Teleogryllus commodus were incubated at 30° C. for 5 days; that is, during the initial 2 days when little change in weight is observed, the third day when the eggs absorb water rapidly, and during 2 more days when little further change in weight is seen. Each day samples of eggs were immersed in tritiated water (100 μcml.-1) at 30, 25, 21, 17 and 120 C. After treatment for 1, 6 and 24 hr. the radioactivity in the shells and in the contents of five eggs from each group was measured. About five times as much radioactivity was found in the contents as in the shells. The activity was greatest at 30° C. and least at 12° C. on all days and at all times. Radioactivity taken up by the eggs was least on the first 2 days, rose sharply on the third day and remained high thereafter. The results are discussed in relation to the mechanism of water-absorption in the eggs.
Adaptive Changes of the Water Permeability of the Teleostean Gill Epithelium in Relation to External Salinity
Authors: Motais R. , Isaia J. , Rankin J. C. , Maetz J. 
Published: April 2021

ABSTRACT
Cannulation of afferent and efferent branchial vessels in the eel permitted studies of tritiated water clearance. It was observed that most of the diffusional water flow occurs through the gills. Diffusional and osmotic water flows have been measured in a fresh-water (Carassius), a marine (Serranas) stenohaline fish and in two euryhaline species (Platichthys and Anguilla) adapted to either fresh water or sea water, and are found to be lower than in any comparable epithelia so far studied. The diffusional water flow deduced from THO turnover is significantly smaller in the sea-water fish. The osmotic water flow, determined indirectly by measuring drinking rate and urine flow, is smaller in the sea-water fishes despite a greater osmotic gradient across the gills. Attempts to compare diffusional and osmotic permeabilities for the gill are hindered by our ignorance of the extent of solute (salt)-solvent interaction in the epithelium. It is suggested that the gill of the fresh-water-adapted fishes is semipermeable, while that of the sea-water teleosts may not be, because of the very high ionic exchange across the gill. The surprisingly low diffusional and osmotic permeabilities of the gill epithelium in sea-water fish may be possibly related to the absence of water-filled pores.
Reflex Organization in the Swimmeret System of the Lobster
Authors: Davis W. J. 
Published: April 2021

ABSTRACT
The dynamic properties of the intrasegmental swimmeret reflexes of the lobster Homarus americanas were studied by recording the discharge of the motor neurones while the swimmeret was moved sinusoidally in its natural arc over a wide range of frequencies. The reflex responses of the excitor neurones of both powerstroke (retractor) and returnstroke (protractor) muscles display hysteresis. In both cases the efferent response corresponding to a given limb position is usually greater during imposed retraction than during protraction. The cyclic efferent reflex response follows the sinusoidal movement stimulus at movement frequencies up to and beyond those which occur naturally during swimmeret beating, with no change in the position of maximum reflex activity in the cycle. The reflexes are therefore capable of influencing the motor output on a cycle-by-cycle basis. The strength of the reflex response is maximum between 1 and 3 Hz. of imposed movement, and declines to either side of this range. The dynamic properties of the reflexes are therefore adjusted so that the maximum amplification of the rhythmic central motor command occurs at the natural frequency of swimmeret beating.
Water Balance in Ilyocoris Cimicoides (L.) (Heteroptera; Naucoridae): The Maximum Osmotic Concentration of the Rectal Fluid
Authors: Staddon B. W. 
Published: April 2021

ABSTRACT
Evidence has been obtained that the excretory system of Ilyocoris cimicoides (L.) is incapable of separating a fluid that is osmotically more concentrated than the haemolymph, that the osmotic concentration of the rectal fluid, relative to that of the haemolymph, attains maximum values only after feeding, and that the osmotic concentration of the rectal fluid has reached a maximum under fasting conditions when it is about two-thirds of that of the haemolymph. In the absence of liquid water there was a rise in the osmotic concentration of the rectal fluid and a rise in that of the haemolymph. However, the former remained significantly less than the latter, a possible explanation being that no significant movement of water takes place across the rectal epithelium.
A Flume for Behaviour Studies of Marine Fish
Authors: Arnold G. P. 
Published: April 2021

ABSTRACT
A flume is described for producing currents of sea water for behaviour studies of marine fish. Its cross-section is 30 cm. wide × 32·5 cm. deep and the observation length is 550 cm. Velocity and depth of water can be finely controlled and the maximum velocity in the level position is 69 cm./sec. with a depth of 10·8 cm. Maximum depth is 29 cm. By tilting the flume the maximum velocity can be increased to 132·5 cm./sec. at a depth of 5·5 cm. with a maximum gradient of 1 in 40. An instrument for measuring current velocity by an optical technique is also described. Its range is 0·8−240 cm./sec. with an accuracy of ± 1% over the range 0·8−8 cm./sec. in its lowest gear and ± 0·5% from 2 to 240 cm./sec. in the higher gears.
Electrolyte Movement in the Isolated Midgut of the Cockroach (Periplaneta Americana L.)
Authors: O’Riordan A. M. 
Published: April 2021

ABSTRACT
The perfused cockroach midgut ventriculus in vitro maintains a p.d. of approximately 12 mV. (lumen negative to haemolymph) in chloride Ringer. The p.d. comprises chiefly a lumen-side Na diffusion potential and a haemolymph-side K diffusion potential. The size of the p.d. is greatly enhanced in sulphate Ringer, but reduced by various metabolic inhibitors, e.g. N2 and 2,4-dinitrophenol. Ouabain inhibits the p.d. from the haemolymph side but is ineffective on the lumen side. The ventriculus preparation also exhibits a net Na efflux of approximately 0 · 3 µ-equiv./hr. Ouabain inhibits Na efflux by almost 55 % and K influx by less than 40 %. It is suggested that a linked Na-K pump is indirectly responsible for the p.d. and directly involved in the Na transport into the haemolymph.
Synchronization of the Locomotor Tidal Rhythm of Carcinus
Authors: Williams Barbara G. , Naylor E. 
Published: April 2021

ABSTRACT
A period of 11 days between tidemarks or below tidemarks entrains a persistent tidal rhythm in Carcinus. Two days exposure is effective between tidemarks but much less so below. Laboratory temperature cycles of tidal periodicity for 5 days will impose a persistent rhythm on crabs kept moist in air when the temperature differential is 11° C but not when it is 4° C. A 4° C differential is effective if crabs are immersed in sea water at the low temperature parts of the cycle. A combination of tidal variables therefore appears to act as synchronizers for the locomotor rhythm and, though not investigated, it is suggested that hydrostatic pressure change is another possible synchronizer. Eyestalkless crabs show increased activity at high temperatures and decreased activity at low temperatures. These responses are the reverse of those occurring in normal crabs and are consistent with the view that eyestalks are the site of an inhibitory neuroendocrine mechanism.
The Ionic Relations of Artemia Salina (L.)
Authors: Smith P. G. 
Published: April 2021

ABSTRACT
The effects of different external media on the sodium and chloride efflux in Artemia salina, the brine shrimp, have been observed, using animals acclimatized to sea water. In sea water, both sodium and chloride fluxes across the epithelium are approximately 7,000 pmole cm. −2 sec. −1. Sodium efflux drops markedly in sodium-free media, and chloride efflux falls in chloride-free media; the two effects are independent, and are not due to changes in external osmolarity. The decreases in sodium efflux can be explained by changes in electrical potential difference and diffusional permeability; exchange diffusion of sodium does not occur. Approximately 70 % of the chloride efflux is due to exchange diffusion, and most of the remainder is due to active transport. It is shown that graphs of ion efflux against external concentration which can be fitted by a Michaelis-Menten equation do not constitute evidence for the presence of exchange diffusion; graphs of similar shape can be obtained if the flux is simply diffusional. The drinking rate, determined from the rate of uptake of 131I-polyvinylpyr-rolidone, is 36 pl. sec. −1, or 2 ·0% body weight hr. −1. The diffusional influx of water is 240 pl. sec. −1.
Studies On Pogonophora
Authors: Little Colin , Gupta Brij L. 
Published: April 2021

ABSTRACT
The oxygen consumption of S. ekmani at 5° C is 0-06 /μl./mg./hr. Phenylalanine and glycine are concentrated by S. ekmani. The concentration factor reaches a maximum after 30 min. in animals removed from their tubes. In animals inside their tubes, the rate of uptake is limited by the rate of diffusion through the walls of the tube. The phenylalanine does not move appreciably into the alcohol-insoluble extract of the animals over a period of 1 hr. Protein is taken up by S. ekmani when animals are removed from their tubes. Uptake is slower than uptake of amino acids, and may involve a different mechanism. Autoradiography using S. mergophorum shows that phenylalanine is not adsorbed on the cuticle. It is found especially in secretory cells, within which it is localized over rough endoplasmic reticulum, Golgi regions and secretion spherules. The site and mechanism of uptake of organic molecules are discussed; and the types of molecules absorbed, together with the significance these may have in the overall metabolism, are considered.
The Response of A Proprioceptor to the Undulatory Movements of Dogfish
Authors: Roberts B. L. 
Published: April 2021

ABSTRACT
Recordings were made from segmental nerve fibres in dogfish while body-wall strips were bent sinusoidally at frequencies and angles comparable with the movements of intact fish. The sensory discharge recorded from a slowly adapting mechanoreceptor in the body wall was proportional to the angular velocity and to the amplitude of the movements. The receptor discharged bursts of sensory impulses during every movement cycle near to the time of maximum velocity. The impulse frequency and the number of potentials in each sensory burst was dependent on the frequency of the bending movement. The number of active units depended on the angle of displacement and on the position of the receptor. These experiments show that this mechanoreceptor could provide information about the frequency and the angle of bending of the body of dogfish during swimming movements.
Studies of the Innervation and Electrical Activity of Flight Muscles in the Locust, Schistocerca Gregaria
Authors: Kutsch W. , Usherwood P. N. R. 
Published: April 2021

ABSTRACT
Four flight muscles, one depressor (M 99) and three elevators (M 90, M 91 and M 120) of the wings of the locust Schistocerca gregaria have been investigated using extracellular and intracellular recording techniques. The innervation and anatomy of these muscles have also been studied histologically. Every fibre in each of these muscles is innervated by ‘fast’ motoneurones. M 99 contains two anatomically distinct ‘fast’ motor units. M 90 contains three ‘fast’ motor units. M 91 and M 120 are innervated by at least one ‘slow’ excitatory and one inhibitory neurone as well as by a ‘fast’ excitatory neurone. Sometimes the inhibitory responses recorded from fibres of these muscles appeared as depolarizing IPSPs. The roles of these muscles in the behaviour of the locust, especially during flight performance, are discussed.
Oculomotor Reactions in the Cuttlefish, Sepia Officinalis
Authors: Collewijn H. 
Published: April 2021

ABSTRACT
Eye position in Sepia was measured in restrained animals, using a scleral search coil technique. Optokinetic nystagmus was elicited by drum rotations from 0·035 up to 35°/sec. Passive rotation of Sepia in darkness evoked a transient nystagmus, followed by after-nystagmus at arrest. Combination of these two stimuli yielded the best results, but the ratio eye velo city/surroundings velocity was usually not better than 0·5. Eye movements were conjugate and a closed eye could be driven by a seeing eye. Monocular reactions were smaller than binocular ones, but equal in both directions. Fixation movements could not be demonstrated in the present conditions.
Observations on the Electrical and Mechanical Properties of the Myotomes of the Lancelet (Branchiostoma Lanceolatum)
Authors: Guthrie D. M. , Banks J. R. 
Published: April 2021

ABSTRACT
Two basic types of mechanical response can be elicited from the lancelet myotome by stimulation of the nerve cord by single shocks: a fast twitch with a rise time of 70-80 msec., and a slow twitch a rise time of 200-250 msec. The two twitch components can easily be elicited together to produce a biphasic contraction. A second type of biphasic contraction occurs more rarely in which the slow phase has a faster rise time and a higher peak tension. The mean of all resting potentials was 48.94 mV. ± 15.5 mV. The commonest values were near 50 mV. and this must refer to the deep lamellae which form the bulk of the myotome. Spontaneous potentials are a striking feature of the lancelet muscles. The fast twitch is accompanied by an all-or-nothing, spike-like potential of between 30 and 70 mV. The slow twitch is accompanied by one or more potentials of between 1 and 10 mV. The type-2 biphasic mechanical response mentioned above is accompanied by two large potentials which attain similar amplitude, but differ in that the second is a graded response. Some of the features of lancelet myotomal muscle have also been described in cyclostomes, nematodes and echinoderms.
Fractionation of Drosophila Populations According to Optomotor Traits
Authors: Götz Karl Georg 
Published: April 2021

ABSTRACT
Behavioural traits of the fruitfly Drosophila are studied as regards their neuronal aspects by appropriate investigation of individual flies, and as regards their genetic aspects by appropriate investigation of population samples. A countercurrent distribution method and a selection-by-inspection method have been developed in order to isolate phototactically deficient mutants from the progeny of the chemically mutagenized homogeneous wild type populations (Benzer, 1967; Pak, Grossfield & White, 1969). Multiple T-mazes and related devices have been used to fractionate heterogeneous populations according to their geotactic or phototactic reactions (Hadler, 1964a, b ; Hirsch, 1967; Hostetter & Hirsch, 1967; Dobzhansky & Spassky, 1967; Dobzhansky, Spassky & Sved, 1969; Murphey & Hall, 1969), according to their spontaneous activity (Levine & Kessler, 1965; Connolly, 1966, 1967) and according to their optomotor response (Siegel & Hirsch, 1963; Siegel, 1967).
Respiration and Osmoregulation in Rainbow Trout with Gills Damaged by Zinc Sulphate
Authors: Skidmore J. F. 
Published: April 2021

ABSTRACT
Damage to the gill epithelium occurs when hatched fish are killed rapidly by solutions of zinc sulphate. The rate of routine oxygen uptake by lightly sedated, quiet, rainbow trout did not alter on exposure to a rapidly toxic solution of zinc sulphate. However, oxygen utilization decreased seven-fold, gill ventilation volume increased six-fold, heart rate was halved, coughing rate increased 18-fold and the of dorsal aortic blood declined. Unsedated trout usually struggled on exposure to zinc. The survival time of struggling fish was reduced and oxygen uptake increased, but other physiological changes were similar to those in quiet fish. The respiratory changes in poisoned trout were generally similar to changes observed earlier in the same fish under hypoxia. The osmotic concentration and the concentrations of sodium, potassium, calcium, magnesium and zinc in blood were largely unaffected by immobilization in zinc sulphate solution. Trout survived a four-fold increase in zinc concentration in the blood by injection. The results suggest that epithelial damage decreased the permeability of the gills to oxygen, and did not increase their permeability to cations. Zinc was not a rapid internal poison. Death was probably caused by tissue hypoxia, when maximum gill ventilation was no longer sufficient to supply the oxygen needs of the fish.
The Effects of Curare in the Cockroach: II. Blockage of Nerve Impulses by dTC
Authors: Friedman K. J. , Carlson A. D. 
Published: April 2021

ABSTRACT
The study of insect curarization in the cockroach, Periplaneta americana, has been continued. The application of curare solution (0·032 M dTC) to the nerve cord produced blockage of action-potential conduction in the giant fibres lying within the nerve cord. The application of curare solution to the cerci prevented the recording of action potentials from the cereal nerves of the organism. Application of dTC to the cereal nerve-A6 region of the cockroach prevented giant fibres from responding to electrical stimulation of the cereal nerves. These results are interpreted as indicating that curare blocks the conduction of action potentials in the cereal nerve. It is proposed that curare can induce blockage of conduction in sensory, motor and central nervous system fibres. It is further proposed that this blockage of conduction is the mechanism of insect curarization. The results of previous reports concerned with insect curarization are re-interpreted in view of the proposal. Several of the conflicts in these reports are resolved by the proposal that blockage of conduction is the mechanism of insect curarization.