bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of the Cleavage in the Frog Egg
Authors: Kubota Tomoyuki
Published: April 2021

The time scale of nuclear division with reference to cleavage time was prepared for the normal egg of Rana nigromaculata. Two experimental procedures, (a) removal and (b) screening of the mitotic apparatus, were performed in the eggs at various times before the beginning of the first cleavage, in order to determine when the furrowing activity of the cortex became independent of the mitotic apparatus. The two experiments concordantly indicated that an autonomous capacity for furrowing was established in the cortex between the metaphase and the late anaphase. Notwithstanding its extremely large size, this critical stage for the frog egg is practically the same as those which have been reported in other smaller cells.
The Physiology of Excretion in the Cotton Stainer, Dysdercus Fasciatus, Signoret
Authors: Berridge M. J.
Published: April 2021

The preparation of isolated Malpighian tubules is described. The rate of urine flow increases with increasing serum dilution, and vice versa. Urine is almost isotonic with haemolymph over a wide range of osmotic pressure. Serum collected from 3-day-old insects promotes urine formation, whereas that from 6-day-old insects does not. A factor which was extracted from the m.n.c. accelerates the rate of urine flow, from a normal value of 0·87 to 3·1 nun.3 × 10−3 /min. The osmotic pressure of the urine, however, remains unchanged. The hormone concentration of different parts of the nervous system was assayed with these isolated tubules. Most activity occurs in the m.n.c., but some activity is present in extracts from the c.c. and the fused ganglionic mass in the mesothorax. Malpighian tubules isolated from 6-day-old insects remain inactive, but after the addition of hormone they immediately begin to produce urine. These observations have been incorporated into a tentative hypothesis on the control of excretion in Dysdercus.
Flight in Drosophila
Authors: Vogel Steven
Published: April 2021

Apparatus has been devised to record the principal parameters of the flight performance of tethered fruit-flies in a wind tunnel. Typically these flies achieve level flight (lift = weight) at 200 cm./sec. and a body angle of + 10°. Lift varies directly with body angle except at very high angles; the stroke parameters are invariant with body angle. Evidence is presented suggesting that these measurements are applicable to free flight. The adaptive significance of the absence of a ‘lift-control’reaction’ in fruit-flies is discussed.
Kinetics and Route of Active K-Transport in the Isolated Midgut of Hyalophora Cecropia
Authors: Harvey W. R. , Zerahn K.
Published: April 2021

The time lag for attaining a steady state of 42K movement from blood-side to lumen was 2-4 min. The flux of was changed as much as 100-fold with but minor effects on the lag time. The specific activity of the gut did not approach 100% of the blood-side value in this short time although the specific activity of K arriving in the lumen from the transport mechanism must be 100%. From these results we conclude : I that the K being transported through the gut cannot be mixing with the total cell K of the gut, and therefore II that the route of K transport may be through just the goblet cells, or III that the K may pass through special pathways between or through epithelial cells.
Locust Wind Receptors
Authors: Camhi Jeffrey M.
Published: April 2021

Tethered locusts begin opening their wings about 45 msec, following wind stimulation of the facial setae. Tethered locusts also begin wing opening at least 30 msec, after release of tarsal contact with the substratum. High-speed ciné photography reveals that an untethered locust in a take-off jump initiates wing opening as early as 15 msec, after the first detectable jumping motion. Therefore in free jumps neither stimulation of the facial setae by the jump wind nor release of tarsal contact is the factor inducing wing opening. The actual mechanism acts much more rapidly, and probably involves central, rather than peripheral, coding. During flight, the extent of forewing pronation on the downstroke is a function of the wind speed over the facial setae, higher speeds resulting in decreased pronation. With increasing wind speed no change in pronation appears until about 80 msec., after which the effect is exaggerated for several hundred milliseconds, finally trailing off slightly to the maintained level. The data suggest that the ‘wind-indicator’ interneurones of the cervical connective are active in the lift-control reflex. A suggested behavioural function of this reflex is rapid ascent following the acceleration produced by a take-off jump.
The Responses of Nephtys (Polychaeta: Annelida) to Changes in Hydrostatic Pressure
Authors: Morgan Elfed
Published: April 2021

An increase in pressure elicited swimming in Nephtys, the number of worms induced to swim being related to the amplitude of the pressure change within the range of stimuli investigated. A decrease in pressure inhibited swimming. The latency of the response to both an increase and a decrease also appears to be related to the magnitude of the stimulus, the worms responding more rapidly to the bigger pressure changes. Brief pulses of pressure lasting 1 sec. elicited neither increase nor decrease in the level of swimming, but pulses of 5 sec. duration induced some individuals to swim. Releasing the pressure at the end of the 5 sec. period resulted in a decrease in the swimming activity below the pre-stimulus level. It is suggested that the different responses may be mediated via separate receptor mechanisms. Phase-angle analysis of the responses to cyclical changes in pressure suggested that the worms were responding primarily to the rate of change of pressure, but the response did not appear to be a simple sine-function of the stimulus. The worms also seemed to be responding in part to some component occurring at twice the basic cycle.
The Renal Excretion of Nitrogenous Compounds by the Duck (Anas Platyrhynchos) Maintained on Freshwater and on Hypertonic Saline*
Authors: Stewart D. J. , Holmes W. N. , Fletcher G.
Published: April 2021

The excretory rates of total nitrogen, uric acid, urea and ammonia by intact birds maintained on fresh water did not differ significantly from the corresponding rates of excretion by birds maintained on saline equivalent to 60 % sea water (284 mM-NaCl, 6·0 mM-KCl). The uric acid excreted by these birds contributed 53·8%, the ammonia 29·2% and the urea 1·5% of the total nitrogen excreted. The three compounds together accounted for 84·5 % of the nitrogen excreted. The glomerular filtration rates (inulin clearance) and the renal plasma flow rates (PAH clearance) did not differ between the freshwater-maintained and the saline-maintained birds. The clearance of uric acid in all groups of birds was equal to the PAH clearance and may be interpreted as a reliable measure of the renal plasma flow rate. The urea:inulin clearance ratios for the individual urine samples from all birds suggested that renal tubular synthesis and secretion of urea may occur. In a second set of experiments uric acid and urea concentrations in the plasma of fed ducks were followed during adaptation to hypertonic saline and during a similar period of dehydration. A sharp in the increase plasma uric acid concentration was generally observed in all groups of birds after feeding and the concentration then gradually declined to the prefeeding level. The plasma urea concentrations of birds given saline equivalent to 60% sea water equilibrated, after the first 24 hr., at about twice the concentration found in the freshwater-maintained birds. In birds maintained on saline equivalent to 100% sea water (470 mM-NaCl; 10 mM-KCl), the plasma urea concentration steadily rose during the first 50 hours and then equilibrated at a level approximately 10 times that observed in freshwater-maintained birds. Withholding all drinking water from birds which had been previously given fresh water resulted in a rise in the plasma urea concentration during the first 50 hr. similar to that observed in the birds maintained on saline equivalent to 100% sea water. But the plasma urea concentration of these birds, in contrast to that of saline-maintained birds, continued to rise throughout the remainder of the experimental period.
Functional Anatomy and Movement Co-Ordination of the Respiratory Pump of the Carp (Cyprinus Carpio L.)
Authors: Ballintijn C. M.
Published: April 2021

An anatomical description of the head skeleton of the carp (Cyprinus carpió) is given. The description is limited to what is relevant for the functioning of the respiratory pumps. An anatomical description of the head muscles of the carp is given. The result of the contraction of most of the head muscles through coupling of skeletal elements spreads farther over the respiratory system than only to the bones to which the muscles are attached directly. It is through this that in the first place all the muscles producing laterad movements, with the exception only of the dilator operculi, influence the volume of both the buccal and opercular cavities, and in the second place that contraction of the hypobranchial muscles not only results in vertical movements of the floor of all the respiratory cavities, but also in laterad movements of their side walls. The hyoid arch plays a central role in the coupling system because it interconnects almost all the other elements. The functional significance of the interaction through couplings is integration of the respiratory movements through which during low-intensity breathing whole muscles can cease to be active and during high-intensity respiration whole muscles can be recruited without seriously affecting the co-ordination of the movements and hence the hydrodynamic efficiency of the pumps.
Interaction of the Movements of the Two Eyecups in the Crab Carcinus
Authors: Barnes W. J. P. , Horridge G. A.
Published: April 2021

The movements of the two eyecups of the crab, Carcinus, have been recorded simultaneously during optokinetic responses. Experiments in which the eyes view different visual stimuli reveal that, at the start of a response, the eyecups have a considerable degree of independence and can even move in opposite directions. As the response progresses, interaction between the eyes increases, until the eyecups move at similar velocities in the direction of the slower of the two visual inputs, or are stationary. Similar interactions between the eyes were observed during memory responses and during the responses to sinusoidal oscillation of the two sets of stripes. Each eye has its own system for converting perceived motion into eyecup movement. These two systems are linked on the afferent rather than the efferent side of the brain. The fast phase of optokinetic nystagmus is governed by the eye whose fast-phase movement occurs away from the midline, and the fast phases of this eyecup lead the other by 30-80 msec. Also, fast phases only occur at their normal frequency when the governing eye can see the stripes.
Two-Dimensional Records Of The Eyecup Movements Of The Crab Carcinus
Authors: Barnes W. J. P. , Horridge G. A.
Published: April 2021

The eyecup movements of the common shore crab, Carcinus maenas L., have been recorded in two dimensions. Saccades and eyecup drift occur in all directions. Eyecup tremor is a complex irregular movement although horizontal tremor predominates in most crabs. Although the response to the movement of the light in a circle is usually an approximate circle or ellipse, rectangular responses are occasionally obtained and the eyecup often moves in a stepwise fashion in response to a smooth diagonal movement of the light. The angle of response to a diagonal movement depends on the ratio of the response to horizontal and vertical movements alone. The eye is virtually stabilized in all planes by a contrasting object but never fixates upon a moving stimulus. No torsional or twisting movements of the eyecups were obtained in response to light stimuli.
The Ionic Basis of Axonal Conduction in the Central Nervous System of Anodonta Cygnea (Mollusca: Eulamellibranchia)
Authors: Treherne J. E. , Mellon DeForest , Carlson Albert D.
Published: April 2021

The compound action potentials recorded in cerebro-visceral connectives consisted of a large homogeneous slow component, with a conduction velocity of between 0·03 and 0·04 m.sec−1, together with a variable rapidly conducting component, showing spikes with maximum velocities in the region of 0·4–0·5 m.sec-1. Comparison of the square of the conduction velocity, for the various components of the compound action potential, with distribution of axon diameters in the connective showed that the small axons (0·1–0·3µ in diameter) contributed to the slow component, the larger axons (2·0–6·0 µ in diameter) forming the initial rapidly conducting spikes. The small axons showed a rapid loss of function in preparations bathed in isotonic sucrose solutions. The larger axons, however, continued to function for appreciable periods in isotonic solutions of non-electrolytes. The larger axons were rapidly and reversibly blocked by dilute tetrodotoxin. Additional evidence is also presented which suggests that the action potentials associated with the axons are sodium-dependent and do not depend upon any appreciable involvement of calcium ions in carrying the action current. Both the large and the small axons appear to be relatively accessible to small ions and molecules in the bathing medium. The results are discussed in relation to the possible physiological mechanisms involved in the function of the larger axons in sodium-free solutions.
Exchanges of Sodium Ions in the Central Nervous System of Anodonta Cygnea
Authors: Mellon De Forest , Treherne J. E.
Published: April 2021

The concentrations of sodium and potassium ions have been measured in the blood and tissues of the cerebro-visceral connective of the freshwater mussel Anodonta. It is shown that, despite the relatively low concentration of sodium ions in the blood, a concentration gradient of this cation is maintained between the extracellular fluid and the nerve cells because of the extremely low intracellular concentration of this cation. Experiments using 24Na and 22Na have shown that there is relatively rapid exchange of sodium ions between the blood and the central nervous tissues. The efflux of labelled sodium occurred as a two-stage process, in which an initial fast fraction gives way to a slower exponential decline. The results can be accounted for on the assumption that efflux of sodium ions in the fast fraction, at o° C., represents the cations contained in the extracellular fluid. This assumption implies that there is little regulation of the over-all concentration of sodium ions in the extracellular fluid. The results are discussed in relation to the available evidence on the structure and electrophysiology of the cerebro-visceral connectives.
The Ionic Basis of the Fast Action Potentials in the Isolated Cerebro-visceral Connective of Anodonta Cygnea
Authors: Carlson Albert D. , Treherne J. E.
Published: April 2021

The large axons in the cerebro-visceral connective have been shown to function for appreciable periods in preparations bathed in sodium-free non-electrolyte solutions. The results of experiments on the effects of organic monovalent cations and anions, together with observations on the effects of tetrodotoxin, procaine and manganous ions and the changes in conduction velocity in tris chloride and dextran solutions indicate that the action potentials are, nevertheless, mediated by conventional sodium-dependent mechanisms. Radioisotope experiments show that there is a small fraction, of approx. 0.5 mM/kg. tissue, which does not exchange rapidly with the 22Na in the bathing medium and which can be depleted by stimulation in sodium-free solutions. On the basis of these observations it is suggested that there is sequestered extra-axonal sodium fraction which can be utilized by the large axons to maintain action potentials in preparations bathed in sodium-free solutions.
Effects of High Hydrostatic Pressures on the Activity and Behaviour of the Ciliate Spirostomum
Authors: Kitching J. A.
Published: April 2021

Spirostomum ambiguum fails to make the avoiding reaction at pressures of 4000 p.s.i. and over. The critical pressure is between 2000 and 4000 p.s.i. Light or moderate mechanical stimulation with a hair no longer produced reversal or body contraction at pressures over 4000 p.s.i. Blows severe enough to kink the body surface, or sudden exposure to NaCl in solution, elicited prolonged reversal at 6000 and 7000 p.s.i. In a direct current the cilia on the cathodal side reversed with a threshold voltage either the same or not more than twice as great as that required without application of pressure. It is suggested that at pressures of 4000 p.s.i. and over the cilia at the anterior end of the organism fail to receive and translate the stimulus. This failure could be due either to the reduced activity of the cilia or perhaps to an impairment of mechanical properties of the ectoplasm.
Irradiation of Sperm Tails by Laser Microbeam*
Authors: Goldstein Stuart F.
Published: April 2021

Sea-urchin and starfish sperm tails were irradiated at pre-selected points along the flagellum and at pre-selected phases of the beat cycle by means of a pulsed ruby laser microbeam. Multiple-exposure dark-field photomicrographs were taken immediately before and after irradiation. The flagellum usually appeared to be broken at the irradiated point. The portion of a flagellum between the head and the irradiated point continued for at least a few beats if its length was at least 25% of the length of the tail, and stopped immediately if it was shorter. Bends already established beyond the irradiated point continued to propagate to the tip of the flagellum. Their propagation velocity generally decreased, and there were usually changes in other bend parameters. No new bends ever developed beyond the irradiated point. Irradiation within a bent region often completely eliminated that region.
Some Requirements for Mating in the Rabbit Flea, Spilopsyllus Cuniculi (Dale)
Authors: Mead-Briggs A. R. , Vaughan J. A.
Published: April 2021

Rabbit fleas Spilopsyllus cuniculi (Dale) do not mate while on adult rabbits; copulation is usually initiated when the fleas are on the body of a new-born rabbit and at least the close proximity of such a nestling is essential. The female probably becomes receptive only after close contact, but not necessarily probing contact, with a young nestling. Fleas with mature ovaries mate much more readily than immature fleas. Male fleas must be in a suitable ‘physiological state’ before they can mate and inseminate females. This state is reached by probing contact with rabbits in the final stages of pregnancy or, for a relatively shorter period, with new-born rabbits. Spermatozoa of such fleas show much greater mobility within the genital ducts than those from fleas kept on male or non-pregnant rabbits.
The Excretion of Magnesium by Carcinus Maenas
Authors: Lockwood A. P. M. , Riegel J. A.
Published: April 2021

Measurements have been made of the concentrations of sodium, calcium and magnesium in the blood and urine of Carcinus maenas after transfer to 50 or 150% sea water. Inulin clearance studies were also made. Magnesium is concentrated in the urine by a secretory process when the crabs are in 100% sea water or 150% sea water. There is evidence that the rate of secretion declines when the crabs are in 50% sea water or in 100% magnesium-free sea water. There is no evidence for active withdrawal of magnesium from the urine. When the blood is depleted of this ion the U/B for magnesium drops to a value similar to the U/B for inulin. The clearance of inulin is faster when Carcinus is in 150% sea water than when it is in 100% sea water, and it is calculated that the animal excretes magnesium at a faster rate than it does in 50% sea water. The excretion of magnesium by Carcinus and Pachygrapsus is compared, and it is shown that magnesium is conserved more effectively in dilute media by Carcinus than by Pachygrapsus. This probably reflects differences in the ecology of the two species.
The Visual Mechanisms of Tenebrio Molitor: Variations Taking Place in the Erg of Pupa and Adult During Development
Authors: Yinon Uri , Auerbach Edgar
Published: April 2021

The changes in the ERG of the compound eye of Tenebrio molitor were measured and followed in both the pupal and the adult stages. In the pupal stage the generally monophasic ERG was found to appear on the second day, and within 7 days reached an amplitude of 0·35 mV. The more complex ERG of the adult beetle increased in amplitude to more than 5 mV. during the following 14 days. The latent periods and peak latencies of the pupal and adult ERGs differed only slightly and did not display any consistent changes with age. 4 The morphological development of the eye was compared with the changes in the ERG.
Water Balance in Ilyocoris Cimicoides (L.) (Heteroptera; Naucoridae): The Rate of Net Water Uptake Through the Cuticle
Authors: Staddon B. W.
Published: April 2021

Measurements have been made of the rate of net water uptake through the cuticle of adult females of Ilyocoris cimicoides(L). With a method that consisted in recording the increase in weight after sealing the external openings of the gut a value of about 10 % of the body weight per day was obtained for the rate of net water uptake through the cuticle at a temperature of 18° C. The Arrhenius equation appeared to hold over the temperature range 4− 26° C. and an approximate value of 10, 530 cals was obtained for the temperature characteristic, μ, of the rate of net water uptake over this range of temperatures. However, the values obtained for the rate of net water uptake at 1°C. (1·8% of the body weight per day) were less than straightline expectation between log. uptake and 1/T over the temperature interval 1− 26°C. would indicate. The results obtained by recording the increase in weight after sealing the external openings of the gut agreed well with those obtained by determining the difference between the intake of drinking water and output of rectal fluid, were somewhat less than the values obtained with a method that consisted in recording the increase in weight after death by ammonia poisoning, and were some four to live times greater than the theoretical values derived on a diffusional basis from the rate of entry of D2O. The results confirm previous evidence that adult waterbugs are typical freshwater animals in the sense that the excretory system must work continuously to eliminate water gained unavoidably and in appreciable amount by osmotic uptake through the cuticle.
The Ionic Relations of Artemia Salina (L.)
Authors: Smith P. G.
Published: April 2021

Measurements of ion concentrations and of electrical potential difference and resistance have been made in Artemia salina, the brine shrimp, using animals acclimatized to sea water. It is believed that the results of the electrical measurements are largely determined by the characteristics of the gill epithelium. The potential difference between the blood and external medium in sea water is + 23 mV. (blood positive). Considered in relation to the ionic concentrations, this indicates that chloride is subject to active transport out of the animal, potassium is pumped in, and sodium is approximately in equilibrium. Measurements of potential difference in other solutions give the permeability ratios Na:K:Li:Cl as 1·00:0·6: 1·0:0·11. The resistance of the gill epithelium in sea water is 40 Ωcm.2. Measurements of resistance in other solutions suggest that lithium ions induce a decrease in cation permeability.
A Re-Examination of the Excretion of Nitrogen by Terrestrial Isopods
Authors: Wieser Wolfgang , Schweizer Gerhild
Published: April 2021

In spring and summer specimens of Porcellio scaber feeding on old poplar leaves excrete from 0·46 to 1·12 ng. dissolved ammonia/mg. body weight × hr. via the faeces, and from 2·3 to 3·25 ng. in gaseous form via the body wall. Non-feeding specimens excrete an average of 11 ng. ammonia/mg. × hr. in gaseous form. In the course of a normal cycle in which periods of feeding activity alternate with periods of inactivity (temporary starvation), faecal ammonia thus constitutes only 10% of the total ammonia released by the animals. If the gaseous component is taken into account, the rate of nitrogen excretion in terrestrial isopods is comparable with that of fresh water and marine species. Oniscus asellus and P. scaber excrete approximately five times more ammonia in spring and summer than in autumn and winter. The faeces produced by P. scaber contain an average of 220 μg. total nitrogen/ 10 mg. of dry faeces of which 2−4% consist of ammonia. Following abrupt changes of temperature, from 5 to 20°C. and from 20 to 5°C. the rates of the release of ammonia and of the production of faeces follow similar time courses, increasing with an initial Q10 of 3·7 if the change is from the low to the high temperature, decreasing with an initial Q10 of 4·6 if the change is in the opposite direction. It is suggested that in terrestrial isopods nitrogen output in the form of gaseous ammonia more or less balances nitrogen input from leaf litter (the animals’ main source of food) and that no reduction of protein metabolism takes place in terrestrial species of isopods as compared with aquatic species.
Studies on Fresh-Water Osmoregulation in the Ammocoete Larva of Lampetra Planeri (Bloch)
Authors: Morris R. , Bull J. M.
Published: April 2021

Sodium influx in ammocoete larvae increases exponentially with external sodium concentration (0-1.0 mm/l.) and sodium-depleted animals show a 20% increase compared with normal animals. Sodium loss decreases as the environmental concentration decreases, although the reverse situation is expected from considering diffusion outflux alone. It is argued that part of the sodium loss is back-transported by the transport mechanism and this accounts for the reduced sodium loss from sodium-depleted animals whose sodium carrier activity is increased. The curves relating back-transport to environmental sodium differ from those derived by Kirschner for isolated frog skin. Sodium influx increases as sodium loss increases, indicating a self mechanism whose features are discussed. In the ammocoete, the sodium carrier mechanism appears to change in affinity for sodium (short-term response) and can also change in concentration (long-term response), and it is suggested that these features, together with permeability changes, may form the basis of the controlling mechanism for sodium balance.
Giant Fibre and Small Fibre Pathways Involved in the Evasive Response of the Cockroach, Periplaneta Americana
Authors: Dagan D. , Parnas I.
Published: April 2021

Giant fibres were found not to activate leg motoneurones during evasion. A pathway of small axons having a conduction velocity of 1 ·5 −3 ·5 m./sec. was found to govern leg activation during escape. This pathway remains functional after giant-fibre degeneration after the giant axons have been severed from their somata. Movements of the antennae were found to be activated by the giant fibres simultaneously or slightly earlier than movements of the legs. It is suggested that a general alarm system is activated by the giant fibres concomitantly with activation of the leg motoneurones by a slower conducting pathway.
Neuromuscular Physiology of the Closer Muscles in the Pedipalp of the Scorpion Leiurus Quinquestriatus
Authors: Gilai Arieh , Parnas I.
Published: April 2021

The closing system of the pedipalp claw in the scorpion is composed of two agonistic muscles situated in both the patella (the longer closer muscle) and tibia (the short closer muscle). Membrane electrical constants of the muscle fibres were found to be : λ = 0·6 mm.; ri = 1 × 106 Ωmm.−1; Ri = 280 Ωcm. ; rm= 4·4 × 105 Ωmm. ; Rm = 830 Ωcm.2; Cm. = 3·6 μF. cm.−2; τ = 3·0 msec.; input resistance = 3·3 × 105 Ω. Each muscle fibre is multiterminally innervated by two motor axons, one initiating a junction potential and the second inducing a post-synaptic spike-like response. The long closer muscle is composed of two anatomically distinct motor units, the short closer muscle of three motor units. Each unit is innervated by its own pair of specific motor axons. No distinction between ‘slow’ and ‘fast’ axons or muscle fibres could be observed. Both muscles responded with a twitch to a single stimulus applied to the nerve. No peripheral inhibition was observed.
Short and Long Memories in Octopus and the Influence of the Vertical Lobe System
Authors: Young J. Z.
Published: April 2021

Octopuses from which either the median superior frontal or the vertical lobes have been removed show reduced capacity to learn to attack an unfamiliar figure. The duration of the increased tendency to attack after feeding is reduced by both operations. This suggests that the failure to learn is due to interruption of a self-re-exciting circuit. Although these operated animals would not attack rectangles they continued to attack crabs for much longer than controls, in spite of shocks. They also retained signs of this inhibition less well. When the median superior frontal lobe alone had been removed the remaining vertical lobe was able to exercise considerable restraint by virtue of its input from below. This shows that the effect of this lobe in preventing attack at a particular figure cannot be wholly due to pre-synaptic inhibition, since the effect can appear when the relevant pre-synaptic fibres are absent. The ‘pain’ fibres are therefore able to activate the vertical lobe to produce inhibition of the system that produces attack at a particular shape.
Lipid, Bile Acid, Water and Dry Matter Content of the Intestinal Tract of Domestic Ducks with Reference to the Habitat of Polymorphus Minutus (Acanthocephala)
Authors: Crompton D. W. T. , Nesheim M. C.
Published: April 2021

The distributions of total material, water, lipid and bile salts in the intestine of domestic ducks feeding ad libitum have been determined. Most material accumulates in the posterior part of the intestine and the duodenal region appears to be wetter than the rest of the intestine. When ducks feed on a diet with a lipid content of 4% of the dry weight, the highest concentration of lipid detected in the intestine was 5 % of the dry weight of the ntestinal material. Lipid appears to be absorbed in the anterior half of the intestine. Bile acids accumulate in the posterior part of the intestine where concentrations as high as 5·18 mg./g. of intestinal contents were detected. The evidence indicates that bile acids are absorbed in the posterior part of the intestine. The bile acids of bile from the gallbladders of ducks have been identified by means of gas-liquid chromatography. Cholic acid, chenodeoxycholic acid, lithocholic acid and some unidentified substances were found to form 16, 59, 17 and 8%, respectively, of the bile acids. The results are discussed with reference to Polymorphus minutus, an acanthocephalan parasite of ducks.
The Orientation of Locusts to A Lamp After Unilateral Injury
Authors: Makings P. , Hussain C. A.
Published: April 2021

Injury to one side of the face, whether on the frons or an antennal patch, affects the orientation of adult locusts to a lamp. For the first 5 days after injury most of them turn the injured side towards the lamp. This tendency is lost or reversed after the fifth day. The change is most evident with a lamp of relatively high power (100 W.); with weaker lamps (60 or 40 W.) the differences are not statistically significant after five days. This phenomenon explains the finding of previous authors that the injured side is usually turned away from a lamp. When the results of numerous tests are added together, those obtained more than 5 days after injury can swamp the earlier ones. Suggested interpretations include the possibility that injury makes the damaged part ‘numb’ until type II neurones are formed in the healed area.
The Mechanics of Stridulation in Bush Crickets (Tettiginioidea, Orthoptera)
Authors: Bailey W. J. , Broughton W. B.
Published: April 2021

Using isolated tegmina of the bush cricket Homorocoryphus nitidulus vicinus (Walker) mounted on the actuator described in a previous paper the parameters controlling tooth-impact rate have been varied. Results have shown that the mirror frame can be thrown into resonant vibration at between 12 and 15 kHz. when the tooth-impact rate approaches these values. The situation in the Homorocoryphus type of stridulation is compared with that of the Conocephalus type where resonance does not occur. The tooth-impact rate in H. n. vicinus is coupled with the frequency of natural vibration of the mirror frame via a plectrum-pivot-frame system which is made to act as a cantilever with the pivot at the mesial end of the vestigial file and the plectrum as the point of excitation. The problem of acoustic coupling involving mechanical and air-column systems is discussed.
Yaw-Correcting Postural Changes in Locusts*
Authors: Camhi Jeffrey M.
Published: April 2021

Changes in the angle of the relative wind sensed by the facial wind receptors of a locust evoke fast rudder-like movements of the abdomen and legs whose magnitudes are proportional to the change of wind angle. This system is sensitive to the angular velocity of the wind change. Such wind changes also evoke rotations of the head about the long axis of the body. The head rotation induces, through proprioception by the cervical hair receptors, slow, redundant rudder-like movements of abdomen and legs. Control elements for the fast movements of abdomen and legs and for the head rotation appear not to be precisely co-ordinated and seem to include no proprioceptive ‘crosstalk’. All these responses are evoked by wind-angle changes only if the insect is flying at the moment, suggesting that flight closes a neuronal switch. Separate motor pathways seem to be employed for the abdomen’s rudder-like response to wind-angle change, head rotation and turn tendency.
The Effects of Curare in the Cockroach: I. dTC-Induced Failure of Leg Contraction
Authors: Friedman K. J. , Carlson A. D.
Published: April 2021

The nature of insect curarization has been investigated in the cockroach, P. americana. Mechanical studies of leg contraction revealed that dTC, whether injected into the abdomen, injected into a leg or applied to the metathoracic ganglion, produces failure of contraction. The contraction failure caused by injecting dTC into a leg or by applying dTC to the metathoracic ganglion could be reversed by washing the drug out of the affected area. The central nervous system does not appear to be essential for curare-induced contraction failure. The contraction of metathoracic legs deprived of their metathoracic ganglion is abolished in the presence of curare. Since curare produces contraction failure when applied to the metathorax and when injected into a leg, the site of curare action must be present in both these locations. The motor nerve fibres are present in both these locations and it is proposed that contraction failure is due to the action of curare on these fibres.
The Spectral Sensitivity and Absolute Threshold of Onchidoris Fusca (Müller)
Authors: Hughes Helen P. I.
Published: April 2021

The response of Onchidoris fusca to monochromatic light in the range 400·650 m· was measured in behaviour experiments with two opposing lights. The peak sensitivity was found to lie at 500−505 mμ. The thick, brown, dorsal skin of Onchidoris has the effect of reducing the sensitivity of the eye to ultraviolet and blue light. After allowing for a 90% absorption of light by the dorsal skin, the absolute threshold of the naked eye of Onchidoris (at 501 mμ) was found to lie between 81 and 106 quanta/sec./eye. If the lens and cornea absorb a further 10% of the available light, then each of five receptor cells in the eye of Onchidoris may be capable of responding to 12−18 quanta/sec. However, the effective threshold of the eye of Onchidoris is much higher, lying at 881−1148 quanta/sec.
The Mechanism and Efficiency of Sound Production in Mole Crickets
Authors: Bennet-Clark H. C.
Published: April 2021

Sound production in the mole crickets Gryllotalpa vineae and G. gryllotalpa is compared with that in Gryllus campestris. In all species action of the plectrum of the left forewing on the file or pars stridens of the right wing causes the harp areas of both wings to vibrate in phase with each other. As the lateral and dorsal fields of the wing are coupled flexibly, the dorsal field resonates freely. The available muscular power of G. vineae is about 3·5 mW., of G. gryllotalpa about 1 mW., and of Gryllus about 1·2 mW. The mesothoracic musculature of Gryllotalpa is fairly similar to that of Gryllus. The calling song of G. vineae has a fundamental frequency of 3·5 kHz, a pulse length of 8 msec, and a pulse interval of 14 msec, at 16°C. The song is very pure with a second harmonic of —26 dB. Simulations of the song made with modulated oscillators are of similar purity; the song can be regarded as a modulated pure note. The sound distribution has been measured, and from the area of an isobar plot and calculation of the mean power of each pulse, the total mean sound power output is 1·2 mW. and the peak power 3 mW. The efficiency of conversion of muscular to acoustic power is about 35%. G. vineae builds a double-mouthed horn-shaped burrow for singing. This contains a bulb which probably tunes the horn to act as a resistive load to the vibrating wings. The double mouths act as a line source with directional properties which concentrate the sound in a disk above the length of the burrow. The probable advantage of a directed sound output in attracting mates is considered; the disk-shaped pattern will be better than a hemispherical pattern of similar power. G. gryllotalpa also builds a hom, but this is larger than that of G. vineae and the song frequency is far lower, at 1·6 kHz. Although the sound power is far lower, about 2·5 × 10−5 W., the horn appears to act as a resistive load to the wings. Gryllus produces only about 6 × 10−5 W. at 30°C. This is attributed to the small size and hence low radiation resistance of the wings. Estimates are made of inertial losses that occur in sound production and these are shown to account for a substantial part of the mechanical power in the systems of both G. vineae and Gryllus.
Qualitative Analysis of the Effect of Thermal Stimuli on the Spontaneous Activity of Tuberous (Knollen-) Organs in Gnathonemus Sp., Mormyridae, Pisces*
Authors: Roth Anton , Szabo Thomas
Published: April 2021

The effect of changes in temperature on afferent nerve activity has been examined in many sense organs bearing secondary sensory cells (Sand, 1938, Hensel, 1955; Murray, 1955, 1956, 1965). In all of these investigations the thermal effect was studied in terms of the change in the number of impulses per second in the afferent nerve fibre connected to the sense organ, or more precisely to the sensory cells. It was shown that the frequency of afferent impulses changes when the temperatures at the receptor site varies, e.g. lowering the temperature (− ΔT° C.) provokes a temporary increase of frequency (‘paradoxical’ thermal effect; see Sand, 1938) and the final frequency after this temporary effect is positively correlated with the decreased temperature (−T° C.) (‘normal’ thermal effect); +Δ °T C. and +T° C. provoke opposite effects.
Differential Blood Flow Through the Afferent Branchial Arteries of the Skate, Raja Rhina*
Authors: Satchell G. H. , Hanson D. , Johansen K.
Published: April 2021

It has been reported that in the rainbow trout, Salmo gairdneri, exercise brings about almost a fivefold increase in the transfer factor of the gills (Randall, Holeton & Stevens, 1967). Five times as much oxygen diffuses from the water to the blood per unit of concentration difference. This suggests that during exercise there is an increase in the area of the functional respiratory surface; this could be achieved if there was an increase in the ventilation and perfusion of some or all of the gills.
Observations On the Myo-Neural Physiology of A Polyclad Flatworm: Inhibitory Systems
Authors: Koopowitz H. , Ewer D. W.
Published: April 2021

The spontaneous activity displayed by Planocera preparations decreased with repetitive electrical stimulation. It was also found that the amplitude of response was related to the time since previous spontaneous activity. The response decreased as the time interval between spontaneous activity and stimulus decreased. When a preparation was stimulated at a low frequency then there was an increase in the tone of the preparation. If the low-frequency stimulus was then followed by a stimulus at a slightly higher frequency then there was a drop in tone caused by a relaxation of the preparation. The extent of relaxation which occurred depended on parameters or the high-frequency stimulus but could be facilitated by increasing either the frequency or the duration of the initial low-frequency stimulus. Pathways involved with conduction of excitation from one side of the animal to the other pass through the brain. The brain is also required for transmission of the relaxation effect. It is concluded that these relaxation and depressant effects reflect the presence of a true inhibitory system which also shows facilitation.
A Quantitative Study of Potassium Movements in the Central Nervous System of Periplaneta Americana
Authors: Treherne J. E. , Lane N. J. , Moreton R. B. , Pichon Y.
Published: April 2021

Using the electrical response of giant axons in the isolated abdominal nerve cord of the cockroach, Periplaneta americana, as an indication of the ionic composition of the fluid bathing their surfaces, it has been shown that the movement of potassium ions from the bathing medium to the extra-axonal fluid, following an increase in the external concentration of this cation, involves an appreciable degree of restriction. This effect is associated with an extracellular diffusion potential, which appears to result from the more rapid penetration of potassium relative to the outward diffusion of sodium ions from the extracellular system. It is suggested that the restriction of intercellular diffusion may occur in the region containing tight junctions and separate desmosomes at the inner end of the intercellular clefts which traverse the perineurium. If the connectives are stretched during mounting, a more rapid depolarization of the giant axons is observed. Comparison of the calculated and the experimentally observed half-times for diffusion of potassium ions to the axon surface indicates that in these preparations the rate of movement of inorganic ions from the external medium is largely determined by the extended intercellular diffusion pathway represented by the mesaxon cleft. In de-sheathed preparations penetration of potassium ions is still more rapid, an effect which is postulated to result from damage to the perineurium, and the consequent production of a shorter, intracellular diffusion channel through the glial system.
Central Control of An Insect Sensory Interneurone
Authors: McKAY J. M.
Published: April 2021

The T fibre habituates little to a series of sine-wave pulses, and recovery is complete within 10 min. Both response level and rate of habituation are increased when the posterior thoracic ganglia are disconnected from the prothoracic ganglion. This indicates that response level and rate of habituation are maintained at a low level in the intact animal by an inhibitory input or inputs to the prothoracic ganglion, which arise within the pterothorax. These inputs are entirely central in origin, and are independent of extratympanal sensory input. The function of the posterior branch of the T fibre to the posterior thorax may be to initiate a feedback loop which is completed by the input from the posterior thorax. It is suggested that such feedback stabilization of the response level would reduce loss of directional information at high stimulus amplitude, preserve discrimination at high stimulus repetition rates and reduce habituation. The implications of these findings for a warning neurone system are discussed.
Host Discrimination in A Gregarious Parasitoid Nasonia Vitripennis (Walker) (Hymenoptera: Pteromalidae)
Authors: King P. E. , Rafai Jamal
Published: April 2021

Females of Nasonia vitripennis cannot distinguish newly parasitized hosts from unparasitized ones but after 60 hr parasitization the parasitized puparia are rejected as oviposition sites. The sheath and stylets of the ovipositor have nerves passing down their canals leading to several types of receptor at the tip of the ovipositor shaft. Differences are detectable in the chemical composition of host haemolymph after 3 days parasitization as compared with the unparasitized condition. These may be the factors bringing about discrimination.
Effects of Sub-Lethal High Temperature On an Insect, Rhodnius Prolixus (Stål.)
Authors: Okasha A. Y. K. , Hassanein A. M. M. , Farahat A. Z.
Published: April 2021

Heat-treatment of Rhodnius adults for 14 or 15 days before feeding may either inhibit egg production during the first reproductive cycle at normal temperature, or cause a great reduction in the number of eggs deposited. In the latter case, oviposition is long delayed. During the subsequent cycles commencement of oviposition and egg production seem to be normal. If heat-treatment is performed immediately after feeding for a similar period, subsequent egg production at normal temperature is apparently not affected, while oviposition is slightly delayed. During subsequent cycles, however, the reproductive activity of the females is not markedly different from normal. The majority of eggs produced under either type of treatment show progressive sterility over a period covering four reproductive cycles. Allowing heat-treated females to copulate with freshly fed normal males results in a great increase in the fertility of the eggs produced. Egg-production, however, does not seem to be affected. The significance of these results is discussed.
Water Relations of the Desert Scorpion, Hadrurus Arizonensis
Authors: Hadley Neil F.
Published: April 2021

Total water-loss rates for Hadrurus arizonensis (0·028% wt/h at 30°C in dry air) are comparable to rates for Old World species and are well below rates for other desert arthropods under similar conditions. Cuticular and respiratory transpiration constitute the two major avenues of water loss, cuticular water loss predominating at temperatures up to approximately 38°C and respiratory transpiration predominating at temperatures above 40°C. The cuticular transpiration/temperature curve exhibits a two-plateau configuration with abrupt increases in cuticular permeability occurring between 35 and 40°C and between 65 and 70°C. Cuticular water-loss values in dead scorpions exceed those of total water loss in living scorpions. The increased cuticular permeability after death is interpreted as evidence for the existence of an active cuticular water-retaining mechanism. Water-loss rates are significantly reduced at lower saturation deficits; however, scorpions are unable to absorb significant quantities of water from near-saturated atmospheres or moist substrates, regardless of their hydration state. The importance of water conserving versus water regaining mechanisms are discussed in relation to the total adaptations of these animals to hot, dry environments.