bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amino Acid Absorption in the Locust (Schistocerca Gregaria Forsk.)
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
Chromatographic analysis of the haemolymph revealed the presence of ten amino acids of which glycine and serine occurred in the relatively high concentrations of 33·2 and 34·6 mM./l. respectively. These two amino acids, together with glutamine (10·9 mM./l.), were selected for the study of absorption from the gut lumen. An experimental solution containing 14C-labelled glycine and serine was injected into the gut lumen and the subsequent changes in concentration and radioactivity of the gut fluid were followed. The uptake of 14C-labelled glycine and serine was shown to occur rapidly in the mid-gut region and especially from the lumen of the caeca. The concentrations of glycine and serine, and also of glutamine, in the caecal fluid were found to increase significantly above their concentrations in the haemolymph, an effect which was paralleled by a relatively rapid decrease in fluid volume. During this time rapid exchange of 14C-labelled glycine and serine between the haemolymph and the gut lumen was demonstrated. On the basis of these observations it was concluded that the net absorption of these substances depended, in part at least, upon the diffusion gradient created by the relatively rapid movement of water into the haemolymph.
The Osmotic and Ionic Regulation of Asellus Aquaticus (L.)
Authors: Lockwood A. P. M. 
Published: April 2021

ABSTRACT
The freshwater isopod Asellus aquaticus can be adapted to media ranging in concentration from 0 · 088 mM./l. NaCl to 200 mM./l. NaCl. In fresh water O.P.1 has a mean value of 150 · 5 mM./l. NaCl. In more concentrated media O.P.I approaches isotonicity with the medium. The mean ion concentrations of the haemolymph of animals in fresh water are Na1 = 137 m-equiv./l., Ch = 125 m-equiv./l. and K1 = 7·4 m-equiv./l. Na and Cl account for most of O.P.I throughout the viable range of haemolymph concentration. Evidence is presented which suggests that the animal is fairly permeable to salts and water. During 8 days’ starvation there is no change in O.P.I, Na1 or Cl1. Sodium and chloride lost from the body can therefore be replaced by active uptake in the absence of food.
The Regulation of the Internal Sodium Concentration of Asellus Aquaticus in the Absence of Sodium Chloride in the Medium
Authors: Lockwood A. P. M. 
Published: April 2021

ABSTRACT
The freshwater isopod Asellus aquaticus has been observed to survive in continuously flowing de-ionized water for up to 16 days. The haemolymph osmotic pressure, and the concentrations of sodium and chloride fall rapidly to about 65% of the normal value and then decrease very slowly until death. Animals loaded to a steady state in 22Na and then washed with de-ionized water lose tracer at a rate which only decreases slightly between the beginning of washing out and the death of the animal. It is suggested that a movement of water from haemolymph to cells as the haemolymph concentration falls may partially account for the maintenance of the haemolymph concentration despite the steady ion loss. Animals loaded for only a short period in tracer before washing out lose about 50-60% of their 22 Na after a few hours in de-ionized water and then show little further loss for a long period. The differences in the tracer loss curves following long-term and short-term loading have been interpreted as indicating that a considerable proportion of the total sodium of Asellus is not in the haemolymph.
The Extra-Haemolymph Sodium of Asellus Aquaticus (L.)
Authors: Lockwood A. P. M. 
Published: April 2021

ABSTRACT
Some 20-30% of the total body sodium of the freshwater isopod Asellus aquaticus is not in the haemolymph. Autoradiography shows that most of this sodium is not uniformly distributed in the tissues but is localized in the cells of Zenker’s organ with lesser amounts in the ovaries, digestive tubules and cuticle. Uric acid is also present in the cells of Zenker’s organ. No evidence is yet available to suggest the function of the sodium in the cells of Zenker’s organ.
Studies on the Exchange and Regulation of Sodium in the Larva of Aedes Aegypti (L.)
Authors: Stobbart R. H. 
Published: April 2021

ABSTRACT
The steady-state exchange of sodium in the 4th instar larva of Aëdei aegypti (L.) has been studied by means of flame photometry and 22Na. The steady-state exchange of sodium between the larva and medium is more rapid in fed larvae (T12 about 10 hr.) than in starved larvae (T12 about 60 hr.). There is no difference between the sodium levels of fed and starved larvae. In both fed and starved larvae about 90 % of the exchange occurs through the anal papillae so these organs must be responsible for about 90 % of the difference between fed and starved larvae in the rate of exchange. Cytological changes in the anal papillae following upon feeding and starvation are described. The results are discussed in terms of possible carrier mechanisms in the anal papillae.
The Sodium Fluxes in the Muscle Fibres of A Marine and A Freshwater Lamellibranch
Authors: Potts W. T. W. 
Published: April 2021

ABSTRACT
Measurements have been made, using 24Na, of the efflux of sodium from the isolated ventricles of Mytilus eduHs and Anodonta cygnaea. In order to determine the efflux of sodium from the muscle fibres it is necessary to correct for the efflux of sodium from the extracellular space. It was not practicable to make such a correction to the results on Anodonta at 15° C. The mean rate constants and effluxes of sodium from the muscle fibres are Mytilus Anodonta at The energy required for sodium extrusion, assuming it is entirely an active process, is: Mytilus Anodonta at
The Form of Beat in Cilia of Stentor and Opalina
Authors: Sleigh M. A. 
Published: April 2021

ABSTRACT
The patterns of beat in cilia of Stentor and Opalina are described. A fibrillar contraction mechanism is suggested to explain the beating of these cilia and of flagella. The diverse forms of beat are thought to result from differences in the relative timing of parts of the contraction process in different organelles. In both types of ciliary beat the effective and recovery phases are in progress simultaneously and are inseparable parts of one continuous contraction process. The average rate of propagation of the contraction wave in Stentor cilia was 844 μ/sec., which is comparable with the rate found in echinoderm sperm tails. In Opalina cilia the rate was much slower at between 20 and 100 μ/sec. The peristomial cilia of Stentor always beat in the same direction, but Opalina cilia may show co-ordinated beat in any direction, and the form of beat appears the same whatever the direction of beat.
Sodium Regulation in the Crayfish Astacus Fluviatilis
Authors: Bryan G. W. 
Published: April 2021

ABSTRACT
In distilled water or artificial tap water with a very low sodium concentration, sodium uptake by Astacus is prevented or reduced and 22Na outflux is subnormal. This is accounted for to only a small extent by reduced renal sodium losses. Sodium-depleted animals replaced in artificial tap water regain sodium in a roughly exponential manner. This is shown by 22Na to be the result of a considerable increase in sodium influx coupled with an increased but lower outflux. Sodium outfiux appears to consist of three components: urine losses, passive diffusion losses over the body surface and what may be an ‘exchange diffusion’ component which is high during high influx and minimal in distilled water. This latter component represents about 30% of sodium exchange under normal conditions. Eyestalk removal did not affect the ability of Astacus to absorb sodium. In starved animals the gills take up most of the sodium absorbed and the gut is relatively unimportant. Silver staining of the gills is a passive process and the cuticle of the branchial filaments of the gill stem is selectively stained. This region would be a suitable site for ion uptake mechanisms.
Internal Factors Controlling the Suboesophageal Ganglion Neurosecretory Cycle in Periplaneta Americana L
Authors: Harker Janet E. 
Published: April 2021

ABSTRACT
Two interacting factors, both following a 24 hr. rhythm, are found to be concerned in the control of the locomotor activity rhythm of Periplaneta americana. When the suboesophageal ganglion is chilled to 3°C., the rest of the body being kept at room temperature, the phases of the neurosecretory cycle are delayed for a period equivalent to the period of chilling. A second cycle, which follows a 24 hr. rhythm, can act as a stimulus to the neurosecretory cycle if the latter is at a stage which responds to a stimulus. If the second cycle affects the neurosecretory cycle the phases of the latter are reset by the stimulus. The phases of the second cycle can be reset by a change from light to darkness while the suboesophageal ganglion is in the chilled state. It appears that the second cycle is immediately reset by the onset of darkness, regardless of the time at which this occurs. The value to the animal, in its natural conditions, of the control of the locomotor rhythm by two interacting cycles is discussed.
A Comparative Study of Gill Ventilation in Marine Teleosts
Authors: Hughes G. M. 
Published: April 2021

ABSTRACTMovements of the lower jaw and operculum have been recorded simultaneously with the associated pressure changes in the buccal and opercular cavities during breathing of the following species: Trachurus trachurus (L.), Clupea harengus L., Gadus merlangus L., Onos mustela (L.), Crenilabrus melops (L.), Cottus bubalis Euphrasén, Blennius ocellaris L., Trigla gurnardus L., Callionymus lyra L., Pleuronectes platessa L., Microstomus kitt (Walbaum), Conger conger (L.), Syngnathus acus L. In all species ventilation of the gills is achieved by the action of a buccal pressure pump and of opercular suction pumps. The time course of the pressure changes indicates differences in the relative importance of the two pumps which are related to the habitat of the fish. The suction pump becomes of greatest importance in fishes which spend most of their fives on the sea bottom. In several species the differential pressure curve does not include the brief period of reversal in pressure gradient found in most fishes so far investigated. Notable among these species are the two flatfishes investigated and in which there is some evidence for an active opercular valve. In general, the results confirm the validity of Baglioni’s classification of the respiratory mechanisms of teleost fishes.
Sodium Regulation in the Crayfish Astacus Fluviatilis
Authors: Bryan G. W. 
Published: April 2021

ABSTRACT
In Bristol tap water containing 0.4 mM./l. sodium and artificial tap water containing 2 mM./l. sodium, Astacus maintains a blood sodium concentration of about 203 mM./l. This value was not markedly affected by starvation periods of up to a month. Methods of taking small blood and urine samples from individual crayfish at intervals over several hundred hours have been described. Under steady state conditions, curves for the uptake and loss of 22Na by the blood are described by equations derived for a one-compartment system. The volume of this single compartment, which exchanges sodium with the medium, is larger than the actual blood volume by an amount roughly equivalent to the sodium in the tissues. Exchange of sodium between the blood and tissues is probably very rapid. Sodium losses in the urine account for about 6% of the total sodium outflux found using 22Na. The urine sodium concentration of about 6 mM./l. was temporarily increased by conditions such as heavy feeding when the blood may have gained additional sodium. Potential difference measurements across the body surface indicate that the high blood sodium concentration is maintained by active uptake of sodium.
Respiration in the Desert Locust
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
Small mirrors are used to record the movements of the spiracle valves of Schistocerca gregaria, and some general observations are made on the synchronized movements of the spiracles with ventilation. Spiracles 1-3 are shown to alter their positions of opening and closing in different carbon dioxide concentrations, within the pattern of synchronized movements. Modifications of the amount of opening of spiracles 1 and 3 take place as a result of differential contractions of the openers. In spiracle 1 the energy is stored in an elastic system, and the opener does not necessarily make contractions every cycle. Oscilloscope recordings show these reactions, resulting from carbon-dioxide stimulation, are controlled entirely from within the central nervous system and do not depend on any sensory input. The movements of spiracle 2 are controlled peripherally through the direct action of carbon dioxide on the muscle membrane (Hoyle, 1960) and also through a cuticular wide-opening device. The maintained sensitivity of spiracle 1 and the increased sensitivity of spiracle 2 after they are uncoupled from ventilation are discussed. Some remarks are made on the activity of the denervated spiracle 2, and the suggestion is made that it depends on a central core of thin fibres. A central nervous mechanism is postulated which could account for the rhythmic cessation of impulses in spiracle and ventilatory nerves.
Force Exerted by a Single Cilium of Mytilus Edulis. I
Authors: Yoneda Mitsuki 
Published: April 2021

ABSTRACT
An important step toward the understanding of the beating mechanism in ciliary movement would be a quantitative analysis of the mechanical properties of the cilium. As a matter of fact, several measurements have been reported concerning the work done by ciliated tissues (Maxwell, 1905) or the force exerted by the whole organism in ciliate protozoa (Jensen, 1893) and flagellated bacteria (von Angerer, 1919). The present paper will deal with the force which a single molluscan cilium can produce during its effective stroke.
The Absorption of Sodium Ions by the Crayfish, Astacus Pallipes Lereboullet
Authors: Shaw J. 
Published: April 2021

ABSTRACT
Sodium influx and net sodium uptake have been measured for the crayfish, Astacus pallipes, in solutions of a variety of sodium salts. The nature of the anion has no effect on the sodium influx. Sodium influx is related to the external sodium concentration in the same way whether the anion is chloride or sulphate. The net sodium uptake rate from sodium sulphate is 65-100% of that from sodium chloride solutions. In sodium sulphate solutions the sulphate ion does not penetrate. There is no increase in ammonia excretion during net sodium uptake from sodium sulphate solutions. An analysis of the external solution by conductivity and ion exchange showed that during sodium uptake sodium ions are not exchanged for metallic cations and must be exchanged either for ammonium or hydrogen ions without increasing their normal rate of excretion. Sodium uptake may sometimes exceed ammonia production so that hydrogenion exchange may be involved in these cases. The possibility is discussed that sodium ions exchange for either ammonium of hydrogen ions depending on the metabolic activity of the animal.
The Absorption of Sodium Ions by the Crayfish Astacus Pallipes Lereboullet
Authors: Shaw J. 
Published: April 2021

ABSTRACT
The effect of various cations in the external solution on the sodium influx in the crayfish, Astacus pallipes, has been studied. Potassium in concentrations up to 4 mM./l. has no significant effect on the sodium influx from 0·05 mM./l. NaCl solutions. Calcium has no effect on the influx in concentrations up to 1 mM./l. At higher concentrations the influx may be reduced in some cases. Magnesium generally increases the influx by about 30%. The effect is not related to the external concentration. Ammonium ions reduce sodium influx. With an ammonium/sodium concentration ratio of 20 : 1 the influx is reduced to about 20 % of normal. Ammonium ions do not affect the sodium loss rate. Simple substituted ammonium compounds have little effect on the influx. The external hydrogen ion concentration reduces sodium influx if the pH is below 6. At pH 4 the influx is reduced to 20–30 % of normal. A low pH does not decrease the rate of sodium loss. The nature of the specific inhibition of sodium influx by ammonium ions is discussed. It is suggested that the ammonium ions interfere with a normal sodium-ammonium exchange mechanism.
The Absorption of Chloride Ions by the Crayfish, Astacus Pallipes Lereboullet
Authors: Shaw J. 
Published: April 2021

ABSTRACT
The mechanism of chloride uptake in the crayfish, Astacus pallipes, has been investigated. In the absence of chloride uptake, chloride is lost from the animal at a mean rate of 0·8μM./hr./10 g. body weight. This is about 72% of the sodium loss rate. In salt-depleted animals, chloride balance can be maintained at a minimum external concentration of 0·028 mM./l. This is lower than the corresponding value for sodium. In salt-depleted animals, chloride is taken up from sodium chloride solutions above the equilibrium concentration, but at about one-third of the rate of sodium uptake. From potassium chloride solutions the net uptake of chloride is slight or non-existent. The addition of sodium increases the rate of net chloride uptake from KCl. The chloride influx is always high and is similar from sodium and potassium chloride solutions. The influx is much higher than expected from measurements of loss rate and net uptake. Up to 90 % of the influx may be accounted for by exchange diffusion. Activation of the chloride uptake mechanism can be brought about if the animal is made deficient in chloride only. Chloride influx is not increased but the rate of net uptake may now be high and account for 70 % of the influx. Net uptake of chloride by chloride-deficient animals takes place against an electrochemical gradient and chloride is exchanged for other anions, probably bicarbonate.
Some Effects of Temperature and Concentration of the Medium on the Ionic Regulation of the Isopod Asellus Aquaticus (L.)
Authors: Lockwood A. P. M. 
Published: April 2021

ABSTRACT
Some effects of temperature and concentration of the medium on the sodium metabolism of the isopod Asellus aquaticus have been studied. The steady-state haemolymph concentration rises with the temperature in the range 5–24° C. The change is, however, only a few mM./l. over this temperature range. The osmotic pressure (O.P.i) and sodium concentration of the haemolymph (Nai) also rise at temperatures below about 4–5° C. The rate of sodium loss from the body is unaffected by temperature. The rate of active uptake of sodium is increased as the temperature is raised. The rate of active uptake of sodium is related to the haemolymph concentration, rising as the Nai, falls. The Nai, is maintained at the normal level in media containing more than 90 μ.M./1. NaCl. Steady states can also be maintained at reduced haemolymph concentrations in media less concentrated than 90 μM./L It is suggested that the homeostatic mechanism regulating the Nai, under the influence of temperature operates as follows. As the temperature falls there is a greater decrease in the rate of uptake than in the rate of loss and hence the Nai, falls. A fall in the Nai, however, results in a rise in the rate of uptake. Therefore after a certain fall in Nai the loss is again balanced by uptake and a new but lower steady state is reached. It is tentatively suggested that high temperatures may assist some brackish-water species in the invasion of more dilute media.
Some Excretory Processes in the Abalone, Haliotis Rufescens
Authors: Harrison F. M. 
Published: April 2021

ABSTRACT
Experiments were carried out on the abalone, Haliotis rufescens, to discover some of the mechanisms involved in urine formation. Test substances were infused into the blood stream and their concentrations followed in serially taken samples of blood, pericardial fluid and urine from the right and left kidneys. Inulin appears to be filtered since its concentration is essentially the same in samples of blood, pericardial fluid and urine from each kidney. The concentrations of phenolsulphonphthalein and p-amino hippuric acid were considerably higher in right kidney urine than in the other fluids, indicating that this kidney is capable of active secretion. Glucose occurred in lower concentrations in the left kidney urine than in blood and pericardial fluid, suggesting a reabsorption of glucose by this kidney. Dye solutions of T-1824 and other materials infused slowly into the pericardial cavity appeared in the urine of both kidneys, suggesting the presence of two functional reno-pericardial canals ; presence of both right and left canals was verified by dissection and observation. From the results obtained it appears that the primary step in urine formation is filtration of blood through the walls of the atria into the pericardial cavity. This fluid then passes via the reno-pericardial canals into the kidneys where on the right side substances may be actively secreted into it and in the left kidney substances may be actively reabsorbed.
The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L.
Authors: Roberts M. B. V. 
Published: April 2021

ABSTRACT
A nerve-muscle preparation including the longitudinal musculature and the giant fibres in the nerve cord of the earthworm is described. Direct stimulation of the nerve cord with single shocks of increasing intensity results in two types of response: (a) a low threshold, very small twitch, resulting from a single impulse in the median giant fibre, and (b) a higher threshold, slightly larger twitch, resulting from single impulses in the median and lateral giant fibres. Both responses are highly susceptible to fatigue. Stimulation of the body surface evokes a much more powerful contraction which is associated with a burst of impulses in the giant fibre. The strength of the contraction depends upon the number of impulses in the burst and this in turn upon the intensity and duration of the stimulus.
Innervation of Locomotor Movements by the Lumbosacral Cord in Birds and Mammals
Authors: Cate J. Ten 
Published: April 2021

ABSTRACT
In earlier experiments (1960) I was able to demonstrate that in pigeons the lumbosacral cord has a high degree of autonomy, and when isolated from the rest of the central nervous system can autonomously co-ordinate walking movements of the hind limbs. A pigeon with the spinal cord transected in the lower thoracic region under normal circumstances can neither stand nor walk ; but when it is placed in a special apparatus (a kind of carriage) so that it is in a normal attitude with the feet resting on the floor it can make genuine walking movements when the hind part of the body is stimulated. It was found essential that the legs be more or less extended and the soles of the feet resting on the floor.