bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal Age and Developmental Variability
Authors: Parsons P. A.
Published: April 2021

Evidence is presented showing that in Drosophila egg-length variability and stemo-pleural chaeta number asymmetry, which are both measures of developmental stability, usually increase with age parabolically, so that both these characters decrease at first to a minimum between the 5th and 12th days of maternal age, then increase to a maximum, although the initial decrease in variability may not necessarily be significant. Maximum hatchability probably occurs at the time of maximum developmental stability. At the time of maximum developmental stability, growing the flies at the extreme temperature of 30° C. has least effect on stemo-pleural chaeta number asymmetry. At this time, therefore, the organism is best buffered against the stresses of the external environment. It is concluded from these studies, and from studies in the mouse and from the literature, that there is an optimum maternal age when the offspring will, in general, be fittest as measured by maximum developmental stability, viability and reproductive ability. It is argued that these results are of application to man, although factors such as variable parental expenditure in man could complicate the situation.
The Relationship between Nutrition, Hormones and Reproduction in the Blowfly Calliphora Erythrocephala (Meig.)
Authors: Strangways-Dixon J.
Published: April 2021

When female blowflies are fed unlimited quantities of ‘protein’ (marmite and milk) and sugar solutions, their corpora allata (c.a.) volumes increase before and decrease during yolk formation in normal females but hypertrophy in ovariectomized flies. If fed sugar solution alone, the ovaries of the flies do not mature and the c.a. in both normal and ovariectomized females remain small. The interpretation and control of these variations in volume were investigated. When ovariectomized or normal females are fed ‘protein’, their c.a. volumes increase in proportion to the quantity consumed. When ‘protein’ is removed from the diet, the c.a. decrease in size. The c.a. respond similarly in both types of fly up to the stage at which yolk is normally deposited. If a further quantity of ‘protein’ is ingested at this stage, the c.a. of normal females increase slightly in volume and then decrease during yolk deposition. But the c.a. of ovariectomized females hypertrophy before decreasing in size. The decrease in c.a. volume during yolk formation may be virtually eliminated by forcing the flies to ingest excess quantities of ‘protein ‘during this phase. The graded response of the c.a. to ‘protein’ consumption suggests that fluctuations of c.a. volume represent variations in activity induced (proportionately) by ‘protein’ metabolites in the blood (there is no accumulation of ‘protein’ in the gut). The decrease in size during yolk formation is due to the removal of ‘protein’ metabolites by the ovaries for the purpose of yolk formation. In ovariectomized flies, these yolk precursors accumulate in the blood causing the c.a. to become hyper-active as indicated by hypertrophy. The responses of the c.a. to ‘protein’ consumption do not appear to be unduly affected by denervation, cutting of the nervi oesophagi or of the cardiac-recurrent nerve. There is slight evidence that the corpus cardiacum is able to store c.a. hormone.
An Isolated Insect Ganglion-Nerve-Muscle Preparation*
Authors: Hoyle Graham
Published: April 2021

A preparation is described which consists of an isolated locust metathoracic ganglion, together with one motor nerve and the skeletal muscle which it supplies (the anterior coxal adductor) in a state suitable for tension recording. Mechanical responses were recorded from the whole muscle, or bundles of fibres and electrical responses of single fibres were recorded intracellularly. Some fibres were found in the muscle which have unusual properties. A single excitatory axon supplies the muscle. Preganglionic stimulation applied to cut nerve trunks may excite an inhibitory-conditioning axon supplying the same muscle. Direct stimulation of the motor nerve was combined with preganglionic stimulation in order to excite the two axons, and their interaction in relation to contraction of the muscle was studied. The preparation shows spontaneous activity in the single excitatory axon supplying the muscle. Various preganglionic stimulations were found to cause prolonged changes in the spontaneous motor output. By correlating the stimuli to the output in certain ways, long-lasting changes in mean output frequency were obtained. These may be regarded as a simple form of learning.
Functioning of the Inhibitory Conditioning Axon Innervating Insect Muscles*
Authors: Hoyle Graham
Published: April 2021

The jumping muscle of locusts is supplied by three motor axons (Hoyle, 1955 a), one of which gives rise to large twitch contractions when stimulated with a single shock and is termed the fast (F) axon, whilst another gives rise to slow contractions only, when repetitively stimulated, and is termed the slow (S) axon (Hoyle, 1955 b). The third axon was found not to give a contraction when stimulated alone but it did cause a hyperpolarization in some of the muscle fibres Thus, by comparison with peripheral inhibitory action at crustacean neuromusclar junctions (Fatt & Katz, 1953), amphibian heart (Hutter & Trautwein, 1956) and cat spinal cord (Eccles, 1953), its function could be expected to be inhibitory; but Hoyle (1955b) found that stimulation of this axon at the same time as stimulation of either of the two excitatory ones did not lead to mechanical inhibition. Instead, the mechanical responses were enhanced, though the effect was slight so functional significance could not be ascribed to it with confidence. Since this phenomenon could not be fully understood it has remained in the background awaiting further investigation.
The Hormonal Control of the Development of Hairs and Bristles in the Milkweed Bug, Oncopeltus Fasciatus, Dall
Authors: Lawrence Peter A.
Published: April 2021

As in Rhodnius, the larval Oncopeltus has bristles which are supplemented at each moult. However, at metamorphosis a dense population of non-innervated hairs develops. Implantation of corpora allata into 5th-stage larvae showed that the development of these hairs can be inhibited universally or locally by the juvenile hormone (JH). Transplantations of integument between 5th-stage larvae of different stages in the moult cycle gave some information about the power of the host to synchronize the graft to its own moult cycle. Transplantations between different larval stages showed that the grafted integument responded to the hormonal milieu of the host. Adult integument was transplanted onto larvae to study the reversal of metamorphosis. It was found that the development of a supernumerary population of hairs depended on the integument passing through a moult cycle in the presence of JH. After two moults in the presence of JH, reversal of metamorphosis was found to vary over the surface of the transplant, being further advanced at the margin. At the edge of the graft properly formed larval bristles developed, while at the centre adult hairs were formed in adult cuticle. Intermediately formed bristles were found in the intervening areas. It is suggested that reactions associated with wounding are the cause of this heterogeneous result. The significance of these results in relation to other work and to theories concerning the mode of action of the juvenile hormone is discussed.
The Thermal Dependence of the Rates of Glycogen and Triglyceride Synthesis in the Mosquito
Authors: Van Handel Emile
Published: April 2021

In poikilothermic animals the dependence on temperature of physiological processes such as growth, respiration, heart-beat, wing-beat, motility, etc., has been studied, but no information seems to be available for the temperature dependence of the synthesis of a defined product. An opportunity to measure rates of synthesis of specific products, namely, the accumulation of caloric reserves, is offered by the female mosquito. When mosquitoes are starved they catabolize all glycogen and triglycerides; after subsequent feeding on a single, measured meal of sugar, quantitative relations can be established between this precursor and its products, the new glycogen and triglyceride pools (Van Handel, 1965 a). In the present investigation, this biological technique has been used to determine the velocity with which these two products accumulate at different temperatures.
The Function of Haemoglobin in Relation to the Maintenance of Neutral Buoyancy in Anisops Pellucens (Notonectidae, Hemiptera)
Authors: Miller P. L.
Published: April 2021

The percentage saturation of the haemoglobin of the intact water bug, Anisops pellucens, in equilibrium with various ambient oxygen tensions has been determined. From this an approximate dissociation curve for the pigment and a P50 value of 28 mm. Hg at 24 ° C. have been obtained. Anisops haemoglobin shows no Bohr effect, but appears to be very temperature-sensitive. During free dives the haemoglobin is regularly de-oxygenated ; the oxygen so derived probably helps to maintain the bug in neutral buoyancy for much of each dive. Carbon monoxide has been used to inactivate the haemoglobin, after which dives are reduced to about one-fifth of their normal duration and the phase of neutral buoyancy is abolished. Much of the oxygen which leaves the pigment probably diffuses into the ventral airstore and then re-enters the tracheal system via the thoracic spiracles. External ‘pumping’ movements may serve to speed this gas migration. It is argued that physical gill action plays a negligible part in the normal respiration of this species.
Activity of Interneurones in the Arm of Octopus in Response to Tactile Stimulation
Authors: Rowell C. H. Fraser
Published: April 2021

A method for recording nervous activity from the nervous system of the arm of Octopus is given. Difficulties of mobility and vasoconstriction are reduced by brain lesions. Three areas were recorded : afferent sucker nerves, axial ganglia, and the dorsolateral axial cord. The sucker nerves include large tactile units corresponding to discrete parts of the sucker rim. These are fast-adapting, phasic, not very sensitive, and are located in the area of motor innervation of the same nerve. Two types of interneurones were found in the axial ganglia, responding to either tactile stimulation of their own or neighbouring suckers, or to proprioceptive input from their own sucker. Motor units to the sucker musculature were also found. Almost all recorded units in the dorsolateral axial cord were interneurones receiving tactile input. They have the following characteristics :

they are rapidly adapting, often phasic, and show little or no ‘spontaneous’ activity. they habituate rapidly to even complex patterns of stimulation and discriminate between them, behaving as ‘novelty units’. different sites of stimulation are discriminated by change in both the number of active units and their temporal patterning. The smallest area shown to be separately represented is the rim of one sucker. prolonged activity can be initiated by a brief initial stimulus, which is without apparent correlated motor output. stimulation of areas outside a unit’s sensory field can lead to activity in that unit or to dehabituation in a previously active unit.

No proprioceptive representation was found.
Respiratory Response to Experimentally Induced Anaemia in the Pinfish (Lagodon Rhomboides)
Authors: Cameron James N. , Wohlschlag Donald E.
Published: April 2021

Injection of phenylhydrazine hydrochloride produced surviving pinfish with as low as 0·26 g. % haemoglobin (2·9% of the normal value). Haematocrits dropped as low as 1–2%, against a normal value of about 30%. Measurements of resting metabolism showed no significant difference related to haemoglobin level, but anaemic fish were slightly higher. Tolerance times at low oxygen levels were not clearly related to haemoglobin levels. Cardiac rates show a compensatory increase in response to haemoglobin reduction which accounts for about 50% of the predicted increase in cardiac output. Haemoglobin is thought to provide a reserve capacity in circulatory ability for oxygen transport through its influence on cardiac output. The reserve capacity is important in meeting unusual demands of migration or escape, and may prove useful in comparing different species.
Free Amino Acid and Haemolymph Concentration Changes in Sphaeroma Rugicauda (Isopoda) During Adaptation to a Dilute Salinity
Authors: Harris R. R.
Published: April 2021

Non-protein and protein nitrogen fractions of the isopod Sphaeroma rugicauda were measured in animals adapted to 100 and 2% sea water. The non-protein nitrogen component was reduced in animals acclimatized to the lower salinity. Free amino acids accounted for 88 and 74% respectively of the non-protein nitrogen in the two salinities. In 2 % sea water taurine, proline, glycine, alanine and glutamic acid showed the greatest decreases in concentration compared to the levels measured in animals adapted to 100% sea water. The decrease in total free amino acids of animals acclimatized to 100% sea water and transferred to 2% sea water was measured. The total free amino acid concentration is reduced to the 2% sea water level within 12 hr. after transfer. Free amino acid, haemolymph sodium and total body sodium levels after transfer to 2% sea water were compared. The asymmetry between the fall in haemolymph sodium concentration and the decrease in total body sodium under these conditions is thought to be due to a water shift from the haemolymph into the tissues. It is suggested that the osmotic pressure of the cells falls at a slower rate than that of the haemolymph.
Locust Wind Receptors
Authors: Camhi Jeffrey M.
Published: April 2021

The sensory cell innervating each wind-receptor hair on the face of the desert locust responds to wind with a slowly adapting train of impulses. Each sensory cell responds maximally to wind flowing in a specific direction. The optimal direction for any sense cell is the same as the angle of curvature of its hair shaft. The optimal wind direction has been determined for each sensory cell of the organ. Three independently measured factors determine a sense cell’s direction response : drag asymmetry of the curved shaft, elastic force asymmetry of the socket, and the eccentric attachment of the dendrite. The sensory cells probably continue uninterrupted through the brain, synapsing first in the suboesophageal ganglion. An accessory neurone of unknown function and unidentified central connexions links each seta with the prothoracic ganglion.
The Nitrogen Balance in Plaice, Sole and Perch
Authors: Birkett L.
Published: April 2021

Plaice, sole and perch were fed on live food for 20−40 days, and their growth rates were compared with their rates of absorption, both measured as mg. N/g. live weight/day. The gross efficiency of nitrogen conversion—that is, the growth per unit of nitrogen absorbed in excess of maintenance—was between 27·5% and 49·0% The maintenance rate of absorption was between 0·173 and 0·499 mg-N/g./day. The basal rate of excretion amounted to 0·056−0·208 mg. N/g./day. At maintenance, total excretion is equal to the amount of nitrogen absorbed from the food. The metabolic cost of growth was 1·04−2·64 mg. N excreted per mg. N retained.
Effects of Various Ions on the Resting and Active Membrane of the Somatic Muscle of the Earthworm
Authors: Hidaka T. , Ito Y. , Kuriyama H. , Tashiro N.
Published: April 2021

The properties of the membrane, in both the resting and the active state, of the longitudinal muscle of the earthworm were studied under various ionic environments. The maximum slope of the membrane potential change against a tenfold change in the external potassium concentration was 27 mV. in the presence of external sodium and 42 mV. in the absence of external sodium. In the normal external potassium concentration the removal of sodium hyperpolarized the membrane from a normal resting potential of – 36 to – 58 mV. Reduction of the external calcium concentration to a tenth of its normal value depolarized the membrane by about 16 mV. In excess of external potassium the spike height and the after-hyperpolarization were decreased and the duration of the spike was prolonged. In sodium-free solution spikes with an overshoot potential were generated both spontaneously and under the stimulus of an intracellularly depolarizing current. The amplitude and the maximum rate of rise of the spike were dependent on the external calcium concentration, whether or not sodium was present externally. Manganese modified the membrane activity by competition with calcium.
The Effect of Splitting part of the Brain or Removal of the Median Inferior Frontal Lobe on Touch Learning in Octopus
Authors: Wells M. J. , Young J. Z.
Published: April 2021

Octopuses with the whole supraoesophageal lobe divided in the mid-line show a lesser preference for smooth objects than normals. Learning of a simple successive tactile discrimination can proceed as fast in such a half-brain as in a whole brain. Animals in which the anterior part of the supraoesophageal lobe alone was split also learned approximately as fast as normals. When tested on the untrained side they showed at most slight signs of ‘transfer’. The unsplit vertical lobe system apparently mediates little transfer, either of learning to take or not to take an object. Animals with the posterior part of the supraoesophageal lobe alone split learned less well than normals or those with anterior splits, the deficit being due to the large number of takes of the negative object. Tests on the untrained side showed that good transfer of the capacity for positive and negative learned response occurred through the intact inferior frontal commissures. Animals without the median inferior frontal lobe showed a marked preference for rough objects. Of six trained with smooth positive only two showed increasingly correct discrimination. Four out of seven animals trained with rough positive showed an increasingly correct performance as a result of training. The performance of the others got worse as training proceeded. It is not clear whether this learning deficit is due to the excessive rough preference or to the absence of some part of the learning mechanism owing to removal of the median inferior frontal lobe. Tests on the untrained side of animals without median inferior frontal show no capacity to discriminate. This shows that the median inferior frontal is vital to lateral transfer and confirms that learning cannot readily be transferred through the vertical lobe system.
An active Reduction of Water Level in Insect Cuticle
Authors: Winston P. W. , Beament J. W. L.
Published: April 2021

The water in cuticles excised from living cockroaches and locusts is not in osmotic equilibrium with their blood. It represents on average an osmotic pressure 15 atmospheres greater than the blood osmotic pressure. In the locust a cuticle in equilibrium with the blood would contain 60% more water. This is cited as evidence for the continuous expenditure of energy by the epidermal cell in regulating the water balance of the cuticle.
Muscle Co-Ordination of the Respiratory Pump of the Carp (Cyprinus Carpio L.)
Authors: Ballintijn C. M.
Published: April 2021

An analysis has been made of the pattern of activity of the muscles of the head of the carp, in relation to respiratory movements and pressures generated in the buccal and opercular cavity, during normal respiration and during coughing. From comparison with the results of analyses carried out on other species of fish it is suggested that the respiratory movements of free-swimming teleosts in general conform to the following principles: the lateral expansions and contractions of the buccal and opercular cavities are always synchronous, but the lowering of the floor of the mouth may be synchronous with, or may precede, the lateral expansion. In the carp the levator operculi muscle, although it inserts on the opercular bone, does not participate in the opercular pump but is the abductor of the lower jaw.
Movement Pattern and Efficiency of the Respiratory Pump of the Carp (Cyprinus Carpio L.)
Authors: Ballintijn C. M.
Published: April 2021

A study of the function of the respiratory muscles is made by influencing the respiratory movements artificially (keeping jaw or opercula open or closed) and analysing the compensatory changes in muscle activity. The differential pressure curves during experiments with mouth and opercula open or closed confirm that the buccal and opercular pump are alternately effective. The respiratory efficiency of the pumps, in terms of both constancy of the water flow over the gills and volume output, decreases if the mouth opens before the transition from compression to expansion of the cavities (as is realized in the trout) and increases if it opens later. In the carp lower jaw abduction occurs at the same time as the transition. An electric analogue of the respiratory pumps has been constructed. It confirms the opinion that the respiratory pressure curves of fishes are generated by a double pump with in-phase cavity movements. Further, it demonstrates that the efficiency of the pumps is greater if lower jaw abduction is synchronous with the onset of cavity expansion (carp) than if it is earlier (trout). The efficiency, however, is shown to be maximal if the mouth opens slightly later.
Histological and electrophysiological Studies On The Giant Axons Of The Cockroach Periplaneta Americana
Authors: Spira M. E. , Parnas I. , Bergmann F.
Published: April 2021

Nerve cords of the American cockroach were cut between the 5th and 6th abdominal ganglia. All giant axons degenerated in the abdominal regions and were present but collapsed in the thoracic connectives. Unilateral lesions permitted identification of ventral giant axons all along the nerve cord. 4. The diameter of abdominal giant axons descreases progressively from 60µ at the metathoracic ganglion to 7 µ at the suboesophageal ganglion. 5. It is concluded that abdominal giant fibres do not synapse at the thoracic ganglia but form narrow isthmuses. 6. The tapering of the giant fibres in the thoracic nerve cord may be responsible for the sequence of nicotine blockade from rostral to caudal regions.
Non-Homogeneous Conduction In Giant Axons Of The Nerve Cord OfPeriplaneta Americana
Authors: Parnas I. , Spira M. E. , Werman R. , Bergmann F.
Published: April 2021

Studies with intracellular electrodes show that the abdominal giant axons of the cockroach give ascending responses to stimulation of cereal nerves and descending responses to stimulation of S0–T1 connectives. In the thoracic region one or more areas of low safety factors occur for descending conduction. These areas, which are considered not to be synapses, are blocked by low doses of nicotine (2-5 µg./ml.) fatigued by repetitive stimulation and show conduction delays of 0·6—0·7 msec. It is concluded that the abdominal giant axons extend continuously from to suboesophageal ganglion. The possibility of bi-directional conduction under physiological conditions is discussed.
Asymmetric Flagellar Movement in Relation to the Orientation of the Spore Of Blastocladiella Emersonii
Authors: Miles C. A. , Holwill M. E. J.
Published: April 2021

The translational and turning movements of the spore of Blastocladiella emersonii are described. The turning movement appears to be a direct result of asymmetric flagellar activity. The results indicate that co-ordination of propagated waves may not be exclusively effected by a system which involves the mechanical properties of the flagellum but also by stimuli derived from another source.
The Production of Cuticle Wax by Engorged Females of the Cattle Tick, Boophilus Microplus (Canestrini)
Authors: Cherry Lois M.
Published: April 2021

Weight of cuticle wax produced by the engorged female cattle tick, Boophilus microplus (Canestrini), and loss of body weight during egg production, have been measured at intervals between dropping from the host and completion of egg laying. Wax increased in weight from 20 to 63 µg. per tick between 6 and 222 hr. after dropping. This increase took place in two stages, with the steepest increase between 6 and 54 hr. and a smaller increase between 78 and 150 hr. Body weight fell by 71 % between 6 and 222 hr. The rate of loss was highest during early egg production, reaching its peak on the fourth day after dropping. The most rapid increase in weight of cuticle wax took place before the onset of oviposition. During peak egg production the increase was slight. During the decline of egg production cuticle wax increased slowly in weight. The possible physiological function of the increased wax secretion, and its relation to general metabolic activity, are discussed.
Water Balance in the Firebrat, Thermobia Domestica (Packard). Exchanges of Water with the Atmosphere
Authors: Noble-Nesbitt J.
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.