bluuebunny/crossref_metadata_2025 huggingface dataset:
Adult Motor Patterns Produced by Moth Pupae During Development
Authors: Kammer Ann E. , Rheuben Mary B.
Published: April 2021

Muscle potentials were recorded extracellularly from developing pupae and adults of the saturniid moths Antheraea polyphemus and A. pernyi and the sphingid moth Manduca sexta. During the week prior to the terminal ecdysis, developing moths still enclosed within the pupal cuticle produced motor patterns similar to those recorded from adults during flight and shivering. The pupal patterns had a longer cycle time and were more variable than the adult motor patterns. Characteristic inter-family differences in adult motor patterns were apparent in pupal motor patterns.

Development of motor patterns was followed over several days by observing individuals with chronically implanted leads. Early in the pupal period potentials were small and infrequent. The amount of activity gradually increased and became more patterned. As development proceeded adult patterns were produced for increasing lengths of time, although the patterns changed quickly and spontaneously.

Restricting the wing movements of A. polyphemus adults increased the cycle time, increased the number of spikes per burst in muscles opposing the restraint, and did not alter the interspike interval within a burst. The flight patterns produced by pharate moths, in which the wings are also immobile, also have a longer cycle time than that of adult flight, but the number of spikes per burst is the same and the interspike interval is longer than in adult flight. These observations suggest that the differences between pupal and adult patterns are not necessarily due to the confinement of the wings by the pupal cuticle.
Delayed Initiation of SS1 Pulses in the Sea Anemone Calliactis Parasitica: Evidence for A Fourth Conducting System
Authors: Jackson A. J. , McFarlane I. D.
Published: April 2021

Single electrical shocks to the column sometimes elicit a series of 1−6 pulses in the SS1 (ectodermal slow system) but the first pulse does not appear until 5−28 s after stimulation. These pulses occur in addition to the early SS1 pulse which follows every shock and which has a conduction delay of less than 1 s. The threshold of the delayed SS1 response is different from the thresholds of the three known conducting systems (through-conducting nerve net, SS1, and SS2). In the case of stimulation of the column, the delayed SS1 pulses do not arise at the point of stimulation but probably originate in the tentacles or upper column. The pulse origin can shift during a single burst. The pathway from the point of stimulation to the site of origin of delayed SS1 pulses is endodermal. We propose that this pathway represents a fourth conducting system (Delayed Initiation System − DIS). The DIS must connect, across the mesogloea, with the ectodermal SS1. The long pulse delay and repetitive firing may derive from pacemaker activity in the DIS. The DIS pacemakers closely resemble the pacemakers connected to the through-conducting nerve net. The DIS may be neuronal. Delayed SS1 pulse bursts from unattached anemones showed an earlier onset, and more pulses/burst, than those from attached anemones. Delayed SS1 pukes can also be evoked by electrical, and in some cases mechanical, stimulation of the pedal disc, tentacles, and pharynx, but there are regional differences in the number of pulses evoked, in their delay, and in their site of origin.
Passive Exchanges During Water Vapour Absorption in Mealworms (Tenebrio Molitor): A New Approach to Studying the Phenomenon
Authors: Machin John
Published: April 2021

The weights of single mealworms were continuously recorded at 20 °C during exposure to periods of constant humidity and to abrupt changes in atmospheric vapour pressure. Two exchange stages were recognized in each animal. Weight changes were either limited to slow losses, suggesting transpiration through the external cuticle, or showed more rapid humidity dependent gains as well as losses. Rapid exchanges indicated that water was gained or lost through permeable barriers, from a fluid compartmet of significantly lower vapour pressure than the haemolymph, equivalent to about 90% R.H. Weight gains and losses during humidity changes provided evidence of a significant, passively exchanging fluid compartment located between the exchange surface and absorbing mechanism. Weight changes in faecal pellets following their elimination provide further support for a rectal site of atmospheric absorption.
The location and mechanism of hyperosmotic fluid secretion in the rectum of the saline-water mosquito larvae Aedes taeniorhynchus
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Authors: Bradley T. J. , Phillips J. E.
Published: April 2021

Ligation between the anterior and posterior segments of the rectum in vitro was used to demonstrate that the posterior rectum is the site of hyperosmotic secretion to the lumen side. Observations were consistent with a reabsorptive function for the anterior rectum. These results support predictions from ultrastructural studies of these two segments. The initial potential of the rectal lumen, relative to the haemocoel side, was of opposite polarity in the anterior (− 10 mV) and posterior (+10 mV) segments and these values decreased to − 2 and + 6 mV respectively in ligated recta which had secreted for 2 h. A comparison of these potential difference measurements with concentration differences developed across the rectal epithelium under the same experimental conditions indicates that Na+, K+, Mg2+, and Cl− are all actively transported by the posterior segment to the lumen side. The influence of different haemolymph concentrations of Na+, K+, and Cl− on the potential differences across the basal cell border and across the whole rectal epithelium are reported. Based on this and previous data, we propose a model for the organization of transport processes within the single celltype present in the posterior rectal epithelium.
The mechanism for co-ordinating metachronal limb movements between joined male and female Artemia salina during precopulatory behaviour
Authors: Lent Charles M.
Published: April 2021

Male and female Artemia salina swim in tandem pairs before copulation and during this period the metachronal rhythms of the individuals are entrained. Artemia entrain to pulsatile water stimulation of the head at frequencies between 4 and 6 Hz. The antennules are mechano-sensitive. Antennular responsiveness to phasic input is very probably the actual mechanism by which interorganism co-ordination is achieved, as mechano-stimulation of other Artemia structures, electro-stimulation and photo-stimulation are ineffective modes of entraining metachronal movements.
EGG Diapause in Ephippiger Cruciger (Orthoptera: Tettigoniidae): I. The Incidence, Variable Duration and Elimination of the Initial Diapause
Authors: Dean R. L. , Hartley J. C.
Published: April 2021

Eggs of the bush-cricket Ephippiger cruciger may be subject to two periods of diapause during the course of embryogenesis. After oviposition not all eggs develop at temperatures favourable to morphogenesis, some cease activity at the unsegmented embryonic primordium stage. If these eggs are cooled for 10–30 days some develop on subsequent exposure to higher temperatures, but further prolongation of the cooling period does not render more eggs competent to develop. Although cooling for longer than the critical period does not affect the proportion of eggs which subsequently start to develop, it does affect the time within which reactivated eggs begin to develop. The delay in the initiation of development after cooling increases with the duration of the chilling period. Excessively long cooling periods, however, impair the eggs’ ability to complete embryogenesis. It is evident that eggs laid in one season will develop and hatch over a number of years.
The locust jump. I. The motor programme
Authors: Heitler W. J. , Burrows M.
Published: April 2021

A motor programme is described for defensive kicking in the locust which is also probably the programme for jumping. The method of analysis has been to make intracellular recordings from the somata of identified motorneurones which control the metathoracic tibiae while defensive kicks are made in response to tactile stimuli. Three stages are recognized in the programme.

Initial flexion of the tibiae results from the low spike thresholds of tibial flexor motorneurones to tactile stimulation of the body. Co-contraction of flexor and extensor muscles follows in which flexor and extensor excitor motorneurones spike at high frequency for 300–600 ms. Flexor inhibitory motorneurones are inhibited. The flexor muscle thus holds the tibia flexed while the extensor muscle develops tension isometrically to the level required for a kick or jump. activity terminates the co-contraction by inhibiting the flexor excitor motorneurones and simultaneously exciting the flexor inhibitors. This causes relaxation of the flexor muscle and allows the tibiae to extend. If the trigger activity does not occur, the jump or kick is aborted, and the tibiae remain flexed.
The mauthner-initiated startle response in teleost fish
Authors: Eaton Robert C. , Bombardieri Rocco A. , Meyer Dietrich L.
Published: April 2021

A characteristic behaviour, the ‘Mauthner-initiated startle response’, was recorded and quantitatively analysed with high-speed cinematography (200 frames/sec) after vibrational stimulation in 11 of 13 teleost species which possess Mauthner cells. The latency of the response is 5–10 msec. This behaviour has: (a) an initial phase, the ‘fast-body-bend’, lasting about 20 msec and consisting of a stereotyped displacement of the head and tail to one side and (b), a second phase, the ‘return-flip ‘, consisting of a non-stereotyped flip of the tail to the opposite side. Within 100 msec after the start of the Mauthner-initiated startle response, most fish were displaced 0·5–1·5 body lengths from their initial position. The variability of the animal’s location after 100 msec suggests that the behaviour is adaptively non-predictable. In goldfish, the Mauthner-initiated startle response could also be elicited by visual stimulation. We conclude that the fast-body-bend is the direct result of activation of one Mauthner cell and its spinal motor neurone pool. In four species we described examples of apparently non-Mauthner initiated startle responses.
Studies on the Action of Biogenic Amines on Cockroach Heart
Authors: Collins C. , Miller T.
Published: April 2021

Measurement of the beat of the semi-isolated cockroach heart, by impedance conversion, showed that the whole abdominal heart of large nymphs or adults responded to low concentrations of acetylcholine (ACh) or 5-hydroxytryptamine (5-HT) by increasing the rate of heartbeat. Preparations, which included 2-chamber sections of the abdominal heart, showed vastly reduced responses to ACh compared to the responses of the whole abdominal heart. Responses to 5-HT were similar in both preparations. Following assay with 5-HT, the cockroach heartbeat often developed marked regularity. ACh assays produced such regularity only rarely. The sectioned cockroach heart preparation was decreasingly responsive to 5-HT > synephrine > octopamine > tryptamine > dopamine > tyramine. Dose-response curves revealed that the antagonist 501 c interacted competitively with 5-HT on the cockroach heart preparation. 501 c appeared to be a non-competitive antagonist to octopamine, suggesting that 5-HT and octopamine act at separate receptor sites on the myocardium. Experiments in which solutions of dibutyryl cyclic AMP, dibutyryl cyclic GMP, or aminophylline were continuously perfused on the cockroach heart, failed to establish that cyclic nucleotides mediate neurotransmitter or hormone action on this tissue. Cockroach hearts were not responsive to prostaglandin E1, F1, picrotoxin, L-glutamate, or ATP below 10−3-10−4M doses.
The Role of Neurosecretion in the Photoperiodic Control of Polymorphism in the Aphid Megoura Viciae
Authors: Steel C. G. H. , Lees A. D.
Published: April 2021

The location of the photoperiodic mechanism controlling the production of the sexual and parthenogenetic morphs by apterous parents was examined by selectively injuring the brain with an R.F. microcautery. Lesions destroying the Group I neurosecretory cells (NSC) in the protocerebrum abolished the response to changed daylength. Extensive damage to other NSC Groups, to the compound eyes and optic lobes was without effect. It is concluded that the Group I NSC are the effectors, secreting a virginoparapromoting substance; in its absence only oviparae are produced. Areas slightly lateral to the Group I NSC are also required for the long-day response, indicating that this is the probable site of the neuronal photoperiodic clock which regulates the release of neurosecretory material (NSM) from the Group I cells.
Behavioural Thresholds for Diffuse Illumination in the Goldfish
Authors: Tavolga William N.
Published: April 2021

Thresholds for diffuse, broad-band illumination were obtained for the goldfish (Carassius auratus) by avoidance conditioning. The light source was a television cathode-ray tube whose output was controlled over a range of 140 dB by a combination of ‘brightness’ control, blanking of scan lines, and neutral density filters. The threshold was calculated in terms of irradiance to be 2·9 ×10−6μW cm−2 (± a standard deviation of 1·4). The determination of absolute, rather than relative, values, and the use of overhead, diflfuse illumination provided data that would be ecologically and behaviourally relevant.
Effects of Median-Fin Amputation on Fast-Start Performance of Rainbow Trout (Salmo Gairdneri)
Authors: Webb P. W.
Published: April 2021

Fast-start performance of eight groups of rainbow trout with various fin-rays removed was measured to test the hydromechanical theory (Weihs, 1973) that large fins are required for acceleration. A trend towards decreasing performance was found for the following sequence of fin-ray amputations: control (pelvic rays amputated); dorsal fin; anal fin; dorsal lobe of caudal fin and ventral lobe of caudal fin; ventral lobe of caudal fin and anal fin; dorsal and ventral lobes of caudal fin; both caudal-fin lobes and anal fin. The series represents progressive reduction in fin and body area, as well as reduction in these areas where lateral movements are largest. Effects of fin amputation on performance were statistically significant (P > 0·05) in comparison with controls only for the last three groups lacking the caudal fin. The results confirm the hydromechanical theory, and lead to the conclusion that mechanically optimum lateral body profiles for faststart and for steady (cruising and sprint) performance are mutually exclusive. This mechanical restriction can be circumvented only in bony fish, with the evolution of flexible, collapsible fins that permit major variation in lateral body profile.
Bursting Pacemaker Activity in the Solitary Hydroid Tubularia Solitaria
Authors: De Kruijf H. A. M.
Published: April 2021

Spontaneous electrical activity recorded from solitary Tubularia solitaria Warren consisted of long bursts of potentials regularly alternating with series of short bursts. Hydranth pulse (HP) systems in isolated hydranths produce a pulse pattern similar to that in intact animals though at a much lower frequency. Stalk pulse (SP) systems in isolated stalks produced extremely regular bursts of pulses resembling bursting patterns in molluscan single neurones. The bursts were associated with strong bending movements. In contrast with hierarchies in other hydroids, T. solitaria’s HP system dominates the SP system.

Excised parts of the stalk produced bursting patterns. Interburst-and interpulse intervals were longer in these parts than in the whole stalk. Numbers of pulses per burst and overall pulse frequency were highest in the most distal part of the stalk, and lowest in the most proximal part.
Urine Production Rate and Water Balance in the Terrestrial Crabs Gecarcinus Lateralis and Cardisoma Guanhumi
Authors: Harris R. R.
Published: April 2021

The rate of urine production in the terrestrial crabs Gecarcinus lateralis (Freminville) and Cardisoma guanhumi Latreille maintained on s.w.-moist sand was measured by inulin clearance. The inulin U/B ratios in both species rose to about unity after 48 h, and remained at this level. It was concluded that neither species withdrew water from the primary urine. The relatively high rate of inulin clearance in G. lateralis (10·69 % body wt day−1) was considerably reduced when animals were transferred to dry sand (2·15 % body wt day−1). The rate of water loss on dry sand was measured in G. lateralis and changes in the haemolymph and urine osmolality recorded. The prevention of possible reabsorption of water from voided urine did not appear to affect significantly the rate of water loss in conditions of water deprivation. The maintenance of urine production rates measured on s.w.-moist sand would double the water loss of G. lateralis in dry conditions.
Body Colour Changes Induced by Spinal Thermal Stimulation of the Crucian Carp (Carassius Carassius)
Authors: Nagai M. , Iriki M. , Iwata K. S.
Published: April 2021

Body colour changes of the crucian carp during spinal thermal stimulation were recorded photoelectrically. Warming the spinal cord induced darkening, whereas cooling induced lightening of body colour. After transection of the medulla oblongata posterior to the vagal lobe, the same colour responses as in intact fish were induced, apart from one of the seven responses to spinal cooling. After spinal pithing, thermal stimulation of the spinal cord failed to induce the responses. The present responses are considered to indicate influence of spinal thermal stimulation on the cutaneous sympathetic systems of this fish.
Metabolic and Tissue Solute Changes Associated with Changes in the Freezing Tolerance of the Bivalve Mollusc Modiolus Demissus
Authors: Murphy Dennis J.
Published: April 2021

A physiological mechanism responsible for increasing the freezing tolerance of the bivalve Modiolus demissus (Dillwyn) following low-temperature acclimation was demonstrated. The rates of oxygen consumption of M. demissus acclimated to temperatures between o and 24 °C were presented as an Arrhenius plot. A change in slope occurred at 10 °C, suggesting that temperature alone was not responsible for the increased decline in the rate of oxygen consumption below 10 °C. Low-temperature acclimation had no effect on blood Na+ or K+ concentrations but did reduce the concentration of blood Mg2+ and, in addition, resulted in the accumulation of end-products characteristic of anaerobic metabolism -tissue alanine and proline, and blood Ca2+. Furthermore, maintenance of M. demissus under anaerobic conditions increased freezing tolerance. Taken together, these data indicate that the increased freezing tolerance of M. demissus acclimated to low temperatures involves a conversion to anaerobic metabolism. The increase in blood Ca2+ following low-temperature acclimation was associated with the increased freezing tolerance. Finally, Mg2+ simulated the effect of Ca2+ on freezing tolerance, but was only 20 % as effective. These results suggest that a Ca2+-dependent mechanism responsible for increasing the freezing tolerance of M. demissus exists, and that the increase in blood Ca2+ is due to a conversion to anaerobic metabolism.
A Calcium-Dependent Mechanism Responsible for Increasing the Freezing Tolerance of the Bivalve Mollusc Modiolus Demissus
Authors: Murphy Dennis J.
Published: April 2021

A time course of the changes in blood Ca2+ and freezing tolerance of Modiolus demissus (Dillwyn) demonstrated that increases in freezing tolerance parallel increases in blood Ca2+. The increases in freezing tolerance occurred rapidly, suggesting that Ca2+ affects freezing tolerance directly by its presence in the blood. The presence of La3+ reduced the freezing tolerance of isolated foot muscle. Thus, Ca2+ appears to increase freezing tolerance directly by binding to cell membranes. The loss of the contractile response of freeze-thawed foot muscle to Ach, KC1 and caffeine and the continued response to CaCl2 suggested that cell membranes are the primary sites of freezing injury. The increase in blood Ca2+ following low-temperature acclimation accounted for only 40% of the total change in freezing tolerance. Therefore, other mechanisms responsible for increasing the freezing tolerance of M. demissus following low temperature acclimation also exist.
The Ionic and Water Relations of Embryos of Lymnaea Stagnalis, A Freshwater Pulmonate Mollusc
Authors: Taylor H. H.
Published: April 2021

From cleavage to hatching Lymnaea stagnalis (L.) embryos exhibit net uptakes of radioactive sodium, potassium and calcium greater than the amounts of these ions initially present in the capsular fluid, implying the early development of mechanisms for ion uptake from the dilute external water. The rates of net uptake increase very rapidly during trochophore to veliger stages when the main volume increase and shell formation takes place.

22Na influx increases dramatically at first cleavage from 0·03 to 0·04 pmol min−1 in the hour before cleavage to 0·23 pmol min−1. A further increase occurs in early cleavage and for decapsulated morula to gastrula stages the influx is estimated to be 2·75 pmol min−1. 22Na efflux rates are also high in decapsulated morulae, blastulae and gastrulae (minimal estimates 1·40–3·35 pmol min−1) indicating a rapid exchange of sodium between the embryos and the medium. In sodium-free medium the 22Na efflux from decapsulated blastulae is 0–5 pmol min−1, suggesting that exchange diffusion is a large component of the fluxes. The characteristics of 22Na efflux indicate that sodium does not exchange with the medium as a single compartment.

Expansion of the’recurrent’ cleavage cavity of early stages is accompanied by a rise in exchangeable sodium content from 5 pmol in embryos without cavities to 11-19 pmol in embryos with normally expanded cavities. Experimental expansions of the blastocoel of morula-blastula stages produced by cyanide are also accompanied by great increases in embryo exchangeable sodium content.

A general model is proposed for the movements of sodium and water in the embryos and this provides a mechanism for hyperosmotic regulation by the embryos.
Innervation of the Ventral Diaphragm of the Locust (Locusta Migratoria)
Authors: Peters M.
Published: April 2021

Innervation and some electrical properties of the locust ventral diaphragm were investigated with electrophysiological and histological methods. Muscle fibres are coupled electrically. Electrical stimulation evokes a graded active membrane response. Each segment is innervated by four motor neurones as follows. Two motor neurones are situated in each abdominal ganglion. Branches of their axons supply the ventral diaphragm in the respective and the next posterior segment. This pattern of innervation was confirmed by axonal Co and Ni staining of the motor nerve endings. Neuromuscular junctions are excitatory. EPSPs show summation but no facilitation. Spontaneous electrical activity of the diaphragm is to a certain degree coupled to activity of the main inspiratory muscles.
On the Activity of the Anterior Lobe Pituitary
Authors: Spaul E. A.
Published: April 2021

The standardisation of the method of preparation of extracts and the adoption of a uniform procedure for the estimation of their ability to induce metamorphosis in axolotls or accelerate the transformation of tadpoles to adults permit a biological assay of the metamorphic activity of extracts of the anterior lobe. The metamorphic activity of the anterior lobe is specific, since similar tissue extracts fail to excite a like response and qualitative and quantitative characteristics distinguish it from the activity of the thyroid in metamorphosis. Active preparations are not produced when neutral media or inorganic acids are used for extraction from fresh gland by decoction. The potency of extracts depends upon the strength of the acetic acid used for extraction, the concentration of the extract and the hydrogen-ion concentration. The threshold value of the dose inducing metamorphosis in axolotls by injection and the amount inducing the maximum rate of change increase with the size of the animal. Injections must be continued at regular and suitably short intervals till the completion of the change to maintain the maximum response to any particular dose. The activity of extracts is destroyed by pepsin and trypsin and diminished by dilute hydrochloric acid. Neutralised extracts are inactive. Ringer’s and distilled water extracts of thyroid are more active than similar extracts in dilute acetic acid. There is no relation between the activity of these extracts and the hydrogen-ion concentration. There is evidence of an inhibiting influence of the posterior lobe upon metamorphosis. The distribution of the factor responsible for the metamorphic activity of the anterior lobe is not uniform throughout the lobe, less being present at the border than within. No definite localisation is apparent. The anterior lobe influences metamorphosis and growth in size, but the same influence does not appear to operate in the production of each of these effects. The extent to which the growth stimulus is dependent upon and determined by other factors has yet to be determined. The thyroid and pituitary are interdependent, but both seemingly are able to Induce metamorphosis in the axolotl independently, and in the absence of the other. In the tadpole independent action in stimulating metamorphosis appears to be possible only in the later stages, co-operation being necessary in development and the earlier stages. The thyroid and pituitary of the adult axolotl appear to be at a low level of functional activity, and metamorphosis is dependent upon the stimulus of glands from external sources when suitably administered, since the rate of change induced is approximately the same in these animals, whether normal, thyroidless, pituitary-less or with both thyroid and pituitary removed. The relationship between the endocrine balance and metamorphosis in the amphibia and its evolutionary significance is discussed. The anterior lobe appears to have a regulative and directive effect within the organism which, as a factor in the internal environment, may have some evolutionary significance.
The Effect of Temperature on Certain Simple Haemolytic Systems
Authors: Ponder Eric , Yeager J. Franklin
Published: April 2021

This paper is primarily concerned with an attempt to evaluate the temperature coefficients for the velocity of haemolysis in two simple haemolytic systems, the lysin being saponin in the first and sodium taurocholate in the second. There is nothing in the literature to suggest that the problem is one of any complexity, for Arrhenius (1915) and his collaborators, by whom most of the existing investigations have been carried out, find that the effect of temperature is adequately described by the well-known Arrhenius equation, the values of μ, ranging from 26,000 when acetic, butyric, or proprionic acids are used as lysins to 38,000 when the lysin is sodium oleate. Their methods, however, are very unsatisfactory, for either the concentration of the lysin or the “time of action” (t.e. time required for the production of a particular degree of haemolysis) is fixed arbitrarily; further, the observations are made over a short temperature range, and usually between 20° and 40°. Such experiments are too restricted to show the complete effects of temperature on the haemolytic systems, and, as will be shown below, lead to quite erroneous results1.
The Electrical Properties of A Crustacean Sensory Dendrite
Authors: Mirolli Maurizio
Published: April 2021

The input properties and the response to stretch of a coxal receptor, the S fibre of the crab Scylla serrata, were studied using two and three intracellular microelectrodes. In the relaxed receptor the transmembrane potential ranged from about –60 to –70 mV, and the input resistance, RT, from 1 to 3 MΩ. The input IV relationship, studied by injecting slow-rising current ramps, was not linear either in the hyperpolarizing or in the depolarizing quadrants. Low values of RT and a linear IV relationship were associated with a large leakage of the microelectrodes. The response to step stretches was complex, consisting of an initial depolarizing transient, Va, and a steady-state depolarizing plateau, Vs. Both Va and Va propagated with decrement in the fibre which was about 9 mm long. The spatial decrement of Va and Vs was equal to that of the response to distally injected current pulses of comparable duration and amplitude. On the basis of the spatial decrement of both Va and Vs the dendrite can be considered equivalent, for current flowing from its distal to its proximal end, to a semi-infinite cable having a length constant of between 4 and 6 cm. The voltage transients recorded in response to long current pulses reached 84% of their final value in a time (t84%)ranging from 150 to 180 ms in fibres in which RT was 2 MΩ or larger. t84% was smaller in fibres having a lower RT. The time course of the transients recorded in response to injected current pulses deviated from the semi-infinite cable model in a manner suggesting the presence of a partial short circuit. For this reason the membrane time constant of the fibre is considered larger (by an undetermined amount) than t84%. The fibre presented less resistance to current flowing from its proximal to its distal end than to current flowing in the opposite direction. For this reason, and also because of the time course of the voltage transient, it is concluded that the distal sensory endings of the fibre have the properties of a leaky end termination, even in the non-stimulated receptors.
Interlimb Coordination During Slow Walking in the Cockroach
Authors: Spirito Carl P. , Mushrush Daniel L.
Published: April 2021

In this study, interlimb coordination in the cockroach during slow walking (2–7 steps/s) is described for a variety of substrate conditions. During normal free-walking, the animal utilizes an alternating tripod gait (both ipsilateral and contralateral phase close to 0·50). The protraction/ retraction ratio varies linearly with walking speed. When tethered on a supported ball, the ipsilateral phase ranges from 0·32 to 0·46 at walking speeds of 2–7 steps/s, and contralateral phase is constant at 0-53. Protraction/ retraction ratios are normal in this case. Blind free-walking animals use a gait which is indistinguishable from normal, but the protraction/retraction ratio is constant over speeds of 2–7 steps/s. When walking down an inclined plane (45°), the gait resembles ball-walking, with an average ipsilateral phase of 0·43 and contralateral phase of 0·53. These alterations of gait under different substrate conditions can be related to the animal’s responses to loading, gravity, and steering control system.
A Sliding Microtubule Model Incorporating Axonemal Twist and Compatible With Three-dimensional Ciliary Bending
Authors: Holwill M. E. J. , Cohen Howard J. , Satir Peter
Published: April 2021

Equations are developed to calculate the relative displacements of the doublet microtubules at the tip of a cilium when the microtubules twist about the axis of the organelle. Displacements measured from electron micrographs show asymmetry (or skew) which can be matched quantitatively by the theoretical model with the appropriate selection of twist angle and orientation of the axoneme with respect to the plane of beat. For Elliptio cilia the experimental results are consistent with a planar effective stroke and a recovery stroke involving a three-dimensional bend. The plane of the effective stroke is not normal to a surface containing the central pair of microtubules but contains microtubule 2 to produce the observed skew. This model for the beat also explains the range of orientations of axoneme observed in sections through the metachronal wave.
Ionic Basis of Action Potentials and Bursting Activity in the Hydromedusan Jellyfish Polyorchis Penicillatus
Authors: Anderson Peter A. V.
Published: April 2021

Knowledge of coelenterate cellular neurophysiology is extremely limited despite the amount of attention this phylum has received from physiologists (cf. Josephson, 1974). However, the recent discovery that reliable intracellular recordings can be obtained from motor neurones in the inner nerve ring of the hydromedusan jellyfish Polyorchis penicillatus (Anderson & Mackie, 1977) presents us with a preparation with which to study cellular events in these organisms. This report describes results from a series of experiments designed to investigate the ionic basis of action potentials in this preparation.
Fluorescence and Luminescence of Isolated Photophores of Porichthys
Authors: Baguet F. , Zietz-Nicolas A. M.
Published: April 2021

Isolated photophores of Porichthys exposed to u.v. light (365 nm) exhibit a green fluorescence localized in the photocytes and a bluish fluorescence originating from the lens-like body. The luminescence of photophores evoked by epinephrine, nor-epinephrine or potassium cyanide decreases with the intensity of the green fluorescence of the photogenic tissue; the bluish fluorescence of the lens-like body does not chnge significantly. The total amount of light emitted is a linear function of the decrease of the greenish fluorescence intensity. The slope of the regression line is maximal in response to epinephrine or nor-epinephrine 5·10−4 M and potassium cyanide 10−3 M. It decreases significantly for higher concentrations. The decrease of fluorescence observed during the light emission is tentatively explained by oxidation of a luciferin present in a fluorescent form in a fresh photophore.
Eclosion Hormone and Bursicon Titres and the Onset of Hormonal Responsiveness During the Last Day of Adult Development in Manduca Sexta (L)
Authors: Reynolds Stuart E. , Taghert Paul H. , Truman James W.
Published: April 2021

The blood titres of eclosion hormone in Manduca sexta indicate that the hormone is liberated into the blood during a span of about 20 min and then disappears with a half-life of about 45 min. Eclosion normally follows 2·5 h after the appearance of the hormone in the blood.

Bursicon appears in the blood within 2 min after the newly emerged moth comes to rest at a wing spreading site. Hormone is apparently released during the following 10 min and then disappears with a of 40–50 min.

The target tissues for the two hormones become responsive during the last day of development. The wing epidermis and nervous system appear to become sensitive to the eclosion hormone at about the same time, approximately 4 h before the hormone’s release. Wings become responsive to bursicon about 2 h earlier.

During the last day of adult development, Manduca show a precise onset of responsiveness to bursicon and eclosion hormone followed a few hours later by the gated release of the two hormones. This appearance of hormone sensitivity is likely to be due to a photoperiodically gated event which occurs late in adult development but prior to eclosion hormone release. The nature of this event is unknown.
The Effect of Epinephrine and Acetylcholine On the Distribution of Red Cells Within the Gills of the Channel Catfish (Ictalurus Punctatus)
Authors: Holbert P. W. , Boland E. J. , Olson K. R.
Published: April 2021

The second pair of gill arches were perfused with 51Cr tagged red cells at constant pressure or constant flow and in the presence of 10−5 M epinephrine or 10−6 M acetylcholine. The tissues were quick frozen, lyophilized and the lamellae and alamellar filaments from the distal, mid and basal thirds of the filaments counted for radioactivity. At constant flow, epinephrine increased red cell space (RCS) in lamellae from basal and mid regions and decreased RCS in peripheral lamellae. The RCS in all alamellar filaments decreased. With constant pressure perfusion, epinephrine increased RCS in all lamellae while alamellar filamental RCS remained unchanged. Acetylcholine, at constant flow perfusion, decreased distal lamellar RCS and increased basal lamellar RCS. RCS decreased in distal and mid alamellar filaments during the same period. These data support the theory of lamellar recruitment as a means of increasing respiratory exchange and stress the importance of concomitant central cardiovascular changes in eliciting maximal response.
Water Exchange Across Fish Gills: The Significance of Tritiated-Water Flux Measurements
Authors: Loretz Christopher A.
Published: April 2021

Branchial turnover rates of tritiated water in the cyprinid teleost Carassius auratus are temperature dependent and show temperature acclimation with time. Hypoxia produced abrupt increases in the rates of branchial water turnover. The evidence suggests the importance of branchial blood flow parameters and ventilation on turnover rate. Membrane resistance is not a major barrier to water diffusion in these small fish. Calculated apparent diffusional water permeabilities do not represent true branchial membrane permeabilities.
Respiration and Adaptation to the Terrestrial Habitat in the Land Hermit Crab Coenobita Clypeatus
Authors: McMahon Brian R. , Burggren Warren W.
Published: April 2021

The frequencies of heart (fH) and scaphognathite (ventilatory = fsc) pumping, and responses to hypoxia, hypercapnia and wetting (simulated rain), as well as oxygen consumption pre-and postbranchial haemolymph oxygen tension oxygen content , carbon dioxide content and pH were measured in adult land crabs Coenobita clypeatus. There was a large increase in fsc in response to both hypoxia and wetting but a smaller increase in response to even severe hypercapnia. Some evidence suggests that ventilation via the scaphognathites may have been supplemented by a second (branchiostegal) pump when ventilatory requirement was high. fH was less responsive to either hypoxia or hypercapnia, but decreased with severe exposure to either. Haemolymph oxygen tensions were low but haemocyanin oxygen affinity was high in vivo (P50= 10 torr at 23°C) and postbranchial haemocyanin was 60–80% saturated. Oxygen content was also high allowing adequate oxygen release to the tissues despite the low oxygen tensions. ΔP50/Δt = 0·37 torr/Δ°C, log ΔP50/ΔpH = −0·84 torr/pH unit, both determined in vitro were lower than literature values for marine and littoral species. As in other terrestrial species, and (calculated) were high, as were both bicarbonate and non-bicarbonate buffering capacities. Water loss was less (0·08% body weight.h−1) in Coenobita than in other terrestrial crustaceans, this resulting from the protection of the adopted shell. Results obtained from Coenobita are compared with those from other terrestrial and littoral crabs to illustrate the influence of the adopted shell on the degree of modification needed to enter terrestrial habitats.
The Spawning of Echinus Esculentus and Some Changes in Gonad Composition
Authors: Stott F. C.
Published: April 2021

The spring inshore migration of Echinus at Port Erin in 1930 started in early February and reached its maximum in the middle of March. Mature gonads were found at the end of February and throughout March and early April. At the end of June all gonads examined were spent. The sea temperature throughout this period was observed. It is probable that May was the chief month in which natural spawning took place. A cycle of changes in the composition of the gonad are recorded from November 1929 to July 1930. The chief of these are: In the males an increase in percentage dry weight as the gonads mature ; the opposite taking place in the females. A large and simultaneous decrease in percentage glycogen in both male and female gonads prior to spawning followed by a great post-spawning increase. The fatty acid content does not alter with the maturation of the gonad, but an indication is given that an increase in the percentage of carbohydrates other than glycogen occurs. Hence it is suggested that glycogen is transformed in the maturing gonad into carbohydrate food reserves for the ripe eggs and sperm.
Iodine Compounds and Fertilisation
Authors: Carter G. S.
Published: April 2021

In the previous papers (Carter, 1930, 1931) results were recorded which led to the conclusion that the egg-secretions of these species of Echinus contain a substance which is similar to thyroxine in its action upon the activity of the sperm. The experiments to be discussed in the present paper were undertaken with the object of observing whether thyroxine is also able to produce effects in the cytoplasm of the egg similar to those normally produced by the secretions.
Observations on Living Cells, Made with the Microscope-Centrifuge
Authors: Harvey E. Newton
Published: April 2021

The microscope-centrifuge, recently described by Harvey and Loomis (1930), was devised in collaboration with Mr Alfred L. Loomis and constructed in his private laboratory at Tuxedo Park, N.Y. It is a device by which living cells can be observed while they are being centrifuged at speeds of 1000 to 4000 R.P.M. at a distance of 11 cm. from the centrifuge axis. The instrument is really a special head, containing part of a microscope, built to fit a 12 in. shaft, the size of the type SB International Equipment Company electric centrifuge. The scheme is as follows.
The Relations Between Yolk and White in the Hen’s Egg
Authors: Smith Michael , Shepherd James
Published: April 2021

The freezing-points of white and yolk in the hen’s egg gradually approach equality when the egg is kept for long periods ; and the rate of the process of equilibration is rapid at first but becomes very slow as equality is more closely approached. Between 0° and 25° C. the rate of equilibration has a temperature coefficient (Q 10) of from 1·5 to 2. At 25° C. equality of freezing-points is reached after about 70 days. Equilibration is achieved partly by the passage of water across the vitelline membrane from white to yolk, but partly also by more complicated changes of osmotic concentration occurring more or less independently in white and yolk. The recovery of hypertony by a yolk, previously diluted by immersion in water, when it is replaced in egg-white can be explained on the basis of a temporary heterogeneity of the diluted yolk, and this explanation is supported by experimental evidence. The rate of equilibration is much greater when the separated yolk is placed in mixed egg-white than in the intact egg, but since it is also greater in thin white than in thick white, and greater again in the white dialysate, the structure and viscosity of the white are probably important factors. There is evidence of an appreciable resistance to water-movement both in egg-white and in egg-yolk. In hypotonic or hypertonic aqueous solutions of glucose or glycerol, or in Ringer’s solution, the rate of equilibration is greater than in egg-white and many times greater than in the intact egg. Water is taken up by the yolk both from hypotonic and hypertonic solutions of Ringer, within the range Δ = 0·10° to 1·20° C., at a rate which increases the further the solution is removed from the point of isotony. Evidence that the apparent disequilibrium in intact eggs is not a steady state maintained by a “Lebenswirkung,” is afforded by: (i) the form of the equilibration curves, which strongly suggest the slow attainment of an equilibrium by diffusion, rather than a steady state terminated by death ; (ii) the temperature relations of equilibration, which are consistent with the former assumption, but which do not agree at all with the effect of temperature on the viability of fertile eggs ; (iii) the absence of any tendency of the yolk to maintain its hypertony when the white is concentrated by rapid evaporation ; (iv) the alternative explanation for the recovery of hypertony by diluted yolks, which was the most crucial evidence for the existence of a steady staté maintained by the expenditure of energy.
The Relations Between Yolk and White in the Hen’s Egg
Authors: Needham Joseph , Stephenson Marjory , Needham Dorothy Moyle
Published: April 2021

The vitelline membrane of the infertile hen’s egg exhibits no dehydrase activity. The vitelline membrane has no measurable aerobic respiration in vitro, nor has the yolk of the infertile egg. This confirms the view that the carbon dioxide production of the intact egg is not the result of any true respiration. When incubated anaerobically in vitro, bacteriologically sterile yolk produces consistently small amounts of lactic acid. This glycolysis is not the result of any catalytic activity of the vitelline membrane, but takes place throughout the substance of the yolk. Under similar conditions, bacteriologically sterile yolk produces small amounts of a substance or substances estimatable as ethyl alcohol. If the yolk suspension is bacterially contaminated, however, lactic acid and alcohol are produced in amounts closely similar to those found by earlier workers on this subject. The heat of glycolysis, under anaerobic conditions, calculated from the amounts of lactic acid experimentally found to be formed, is of the same order as (a) the calculated requirement of the vitelline membrane (Straub), and (b) the observed heat production (Langworthy and Barott). Thus even if the vitelline membrane is capable of using energy to do osmotic work, the yolk is only capable of supplying it by means of its glycolytic mechanism if the whole energy output of the whole yolk can be made available for doing work at the membrane.
The Relations Between Yolk and White in the Hen’s Egg
Authors: Needham Joseph
Published: April 2021

In a previous paper of this series it has been stated that yolk and white, separated only by a thin collodion membrane, come rapidly into osmotic equilibrium. The converse experiment to this would consist in isolating the vitelline membrane from the yolk and white and studying its osmotic properties in relation to solutions of simpler composition than the egg contents. Under such conditions, with a solution of salts equivalent to the yolk on one side, and a solution of salts equivalent to the white on the other side, would the membrane maintain the difference or not?
Respiratory, Ventilatory, and Cardiovascular Responses to Experimental Anaemia in the Starry Flounder, Platichthys Stellatus
Authors: Wood Chris M. , McMahon B. R. , McDonald D. G.
Published: April 2021

Unrestrained, quiescent starry flounder maintained approximately normal levels of O2 uptake in the face of severe experimental anaemia. At haematocrits above about 5 %, the only major compensation was a reduction in venous O2 tension which lowered venous saturation and thereby kept a constant difference between arterial and venous O2 contents. Below a haematocrit of about 5 %, this difference decreased, and many additional compensations were invoked, including increases in ventilation, expired O2 tension, arterial O2 tension, and cardiac output, and decreases in systemic vascular resistance and blood pH. All changes could be reversed by restoration of haematocrit. Exercise performance and post-exercise changes in blood pH and lactate differed only slightly between anaemic and normal flounder. In wild flounder, anaemia commonly occurs and apparently only causes death at the haematocrit value (about 5 %) below which most major compensations are implemented. The respiratory strategy of the flounder during anaemia is compared with that of the rainbow trout.