J. L. Cloudsley‐Thompson

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Interest in biofuels is largely driven by the desire to reduce carbon emissions, achieve energy security, and spur economic development in response to the hazardous effects of fossil fuels. As third-generation biofuel feedstocks, cyanobacteria are highly advantageous since several biochemical processes can be applied to these organisms, enabling the production of a variety of fuels, including biogas, cellulosic ethanol, and biodiesel. High net energy converting biomass into fuel, growth on nonagricultural and marginal lands, ability to thrive in brackish and marine waters, and production of high-value by-products, such as proteins, pigments, and other extracts, offer endless possibilities for researchers and entrepreneurs. With simpler metabolic processes relative to eukaryotic organisms that have been well-established, cyanobacteria are a highly tractable platform for building efficient pathways for biofuel production. This chapter focuses on the major steps of the cyanobacteria-to-fuel process, types of fuel produced, genetic engineering, and advances aimed toward improving the commercial viability of these products, and challenges in scale-up production.

The dry-season biology of a member of the Anopheles gambiae complex (probably species B) was studied in 2 areas in the Khartoum region of Sudan. It was found that in the valley of the White Nile the species maintained itself by low-level breeding, as shown by the continuing presence of larvae, male mosquitos and parous females through the dry months (9 months in the year). In the scattered villages of arid areas situated more than 20 km from the Nile Valley, on the other hand, regular sampling through the cool dry and hot dry months of the year failed to detect any An. gambiae except nulliparous females. These were found in occupied huts, deserted huts, dry wells and animal burrows.The great majority of 213 females collected in the 11 dry months between November 1966 and December 1967 had fresh or older blood-meals but the abdomen was never found fully distended in the dry season. Examination of the ovaries showed that they did not develop beyond Christophers' stage II in the period from November to February, stage III in March and April, or beyond stage IV in May. But, in June and July stage IV and V ovaries predominated and few specimens remained in stage late-II.It is inferred from these observations that the local population of An. gambiae is highly adapted to survive in the adult stage through the severe drought and heat of the arid zone of Sudan. Some feeding activity continues but ovarian development is extremely retarded, and only one batch of eggs matures during the whole 9-month period. Evidence collected in the Nile Valley indicated that female An. gambiae in that area were not subjected to similar retardation of the ovarian cycle; in fact, clear evidence was obtained there of continuous year-round breeding by the mosquito.

It is not easy to evaluate the adaptive functions of rhythmic activities in animals for two reasons. First, because the interaction of the various physiological and ecological components is usually extremely complex; secondly, because the environmental factors to which rhythms are geared (“clues,” “synchronizers,” “Zeitgeber”) may bear little direct relation to the ecological factors most significant to the animal. For example, distribution of the webs of the Mediterranean spider Filistata insidiatrix (Forsk.) is determined by temperature, although the spiders stay in their heat-insulated tubes during the day. Now the prey of this species consists chiefly of woodlice, which are also nocturnal, and the spiders' webs are most numerous on the cooler and damper rocks where woodlice abound [1]. Again, the periodicity of the woodlouse Oniscus asellus (L.) depends upon the cycle of light and darkness, and is independent of temperature and humidity, although the latter factor is probably the...

ABSTRACT A composite diurnal locomotory rhythm has been established in the woodlouse Oniscus asellus. This is correlated primarily with alternating light and darkness, and not with fluctuating temperature or humidity. The intensity of the humidity response of the species is less in darkness than in light, and less still in darkness when the animals have been kept in darkness for some days previously. It increases with desiccation. The response to light is greater, too, in animals which have been kept in darkness for some days, and these tend to remain photo-negative in dry air whereas controls become photo-positive with desiccation. The sensitivity to carbon dioxide is much greater in animals from a culture kept in darkness than it is in controls. The results obtained are discussed in relation to the nocturnal ecology of the species.

ABSTRACT The species of woodlouse investigated are known to stand in the following order as regards the rate of water loss by transpiration : Philoscia muscorum > Oniscus asellus > Porcellio scaber > Armadillidium vulgare. The intensity of the responses of the four species to humidity at room temperature (18+ 2° C.) are compared and are shown to stand in the same order. The intensity increases as desiccation proceeds. At low temperatures (3 ± 2° C.) the intensities of the reactions to humidity are much reduced and are the same in all species; at higher temperatures (30 ± 2° C.) the humidity responses of Ph. muscorum and O. asellus are again somewhat reduced, and it is suggested that this may be correlated with a lower thermal death-point and the need to effect a reduction in body temperature by evaporation. The antennal cone sensillae are shown to be contact chemo-receptors ; no specific sense organs are concerned with the appreciation of humidity. The response is correlated with saturation deficiency rather than with relative humidity and is probably engendered by dehydration. Ph. muscorum is the most strongly photonegative of the species and there is a graduation through O. asellus and P. scaber to A. vulgare which is the least so. Ph. muscorum is also shown to be the most intensely nocturnal in habit, A. vulgare the least. It is therefore suggested that the degree of nocturnal activity is correlated with the ability to withstand water loss by transpiration. The results obtained are discussed in relation to the ecology of the species.

SUMMARY. The behaviour and sensory physiology of Paradesmus gracilis (C. L. Koch) and Blaninlus guttulatus (Bose) have been investigated. Both species posses a dermal light sense, and respond to light stimuli by means of a simple orthokinesis. Their temperature reactions fall into three categories: a general orthokinetic metabolic effect upon speed of locomotion, duration of spiral reflex, etc., a preference shown klinokinetically for temperatures about 15°C.; and orthokinetic activity stimulated by sudden drops in temperature. The temperature sense cannot be aseribed to any particular sensillae, but resides in the antennae as well as elsewhere. Positive geotaxis become apparent under the influence of the orthokinesis engendered by desiceation. The Tömösvary organs may be gravity receptors, but if so the stimulation of various proprioceptive organs by the weight of the body acting on limtes is probably also concerned in the reception of the stimulus. No orthokinetic response to humidity comparable with that found in woodlice and wireworms has been observed: the millipedes show maximum locomotory activity at all humidity ranges, but once they have finally come to rest, they do not readily start moving again. Responses to moisture, however, are far more important in their behaviour; they are purely orthokinetic, and probably a general effect of dehydration. Possibly both Tömösvary organs and trichoid sensillae register vibrations: the millipedes respond by curling up (spiral reflex), but very slight vibrations frequently stimulate locomotory activity. Reactions to contact stimuli are of very great significance in the behaviour of millipedes. They are chiefly orthokinetic, and the tactile hairs on the limbs, sides of the body, and particularly on the antennae are the sensory receptors. Millipedes do not respond to odours, but there is an orthokinetic “attraction” to gluclose and sucrose with a threshold about 0·5 gm. litre. There is no attraction to asparagine and strach, but urea repels Blavials. Antennary and gnathochilarial basiconic sensillae are the receptors for contact chemical stimulation. Removal of, or painting over the antennae induces a state of depression which persists until death. The significance of the behaviour and sensory responses of millipedes in relation to their ecology is discussed with particular reference to the importance of Blaniulus as an agricultural pest.

Ecophysiology of Desert Arthropods and Reptiles starts with a new classification of the world's deserts, based upon the type of precipitation to which they are subject and the effect of this on their faunas of arthropods and reptiles. This is followed by an account of microclimates and the avoidance of environmental extremes. Where thermoregulation is primarily behavioural, responses to water shortage are largely physiological. Seasonal activity and phenology are described, as well as adaptations for burrowing, the avoidance of enemies and defence. A comparative account of interspecific relationships, feeding specializations, and species diversity in the two taxa is described. The purpose of the book is to provide an up-to-date analysis that will stimulate further research.

Lethal temperatures for 24 hours' exposure below 10 per cent relative humidity were highest for scorpions and 'camel‐spiders' and higher for tenebrionid beetles than for crickets, cockroaches and earwigs. The rate of water‐loss increased around the lethal temperature: pre‐conditioning for 24 hours resulted in enhanced resistance to high temperatures for up to four hours. Heat death in Ocnera hispida is not related to water‐loss and excess moisture adversely affected survival. Death was associated with a decrease in blood pH in this species and in the scorpion Leiurus quinquestriatus. It is suggested that heat death cannot be attributed to a single factor, but that in these cases it may be primarily related to the accumulation of acid waste products of metabolism. Réasuméa TEMPÉRATURES LÉTALES DE QUELQUES ARTHROPODES DÉSERTICOLES ET LEUR MODE D'ACTION Un nombre d'arthropodes déserticoles a été exposé à des températures létales pendant 24 heures à line humidité relative inférieure à 10%. Les températures létales des scorpions et des Solifuges étaient beaucoup plus élevées que celles des insectes; les températures létales des coléoptères tenébrionides dépassent celles des espèces d'insectes cryptobiontes. Le degré de perte d'eau augmente au voisinage de la température létale. La résistance aux températures élevées est augmentée d'un maximum de 4 heures par une acclimatisation préalable de 24 heures. La mort d 'Ocuera hispida par la chaleur n'est pas causée par une perte d'eau; la présence d'un excès d'humidité exerce un effet néfaste sur la survivance. Chez cette espèce et chez le scorpion Leiurus quinquestriatus la mort est associée à une baisse du pH sanguin. L'auteur suggère que la mort ne peut être attribuée à un seul facteur, mais qu'elle est causée, dans le cas des espèces mentionnées, par l'accumulation de produits résiduels acides du métabolisme.

STUDIES IN DIURNAL RHYTHMS.–V. NOCTURNAL ECOLOGY AND WATER-RELATIONS OF THE BRITISH CRIBELLATE SPIDERS OF THE GENUS CINIFLO BL Get access J. L. Cloudsley-Thompson, M.A., Ph.D., F.R.E.S., F.L.S., F.Z.S. J. L. Cloudsley-Thompson, M.A., Ph.D., F.R.E.S., F.L.S., F.Z.S. 1Department of Zoology, University of London King's College Search for other works by this author on: Oxford Academic Google Scholar Zoological Journal of the Linnean Society, Volume 43, Issue 290, January 1957, Pages 134–152, https://doi.org/10.1111/j.1096-3642.1957.tb02515.x Published: 28 June 2008

ABSTRACT Visual experiments on two small British species of millipedes have demonstrated that the diurnal cycle of rhythmic activity as represented by the number of animals on the surface is primarily a response to light and darkness, but is also correlated with the stimulus of falling temperature in the evening. Aktograph experiments on two large West African species of millipedes have demonstrated an endogenous diurnal rhythm independent of fluctuating light and temperature, and persisting (in Ophistreptus) up to 19 days. Locomotory activity is stimulated both by increases and decreases of temperature; and it is probable that temperature fluctuations are of primary importance in the initiation of diurnal rhythms. The effect of light on activity is slight, but constant temperatures over long periods have, a depressing effect.

Amniotes are tetrapod vertebrates that are united by a common reproductive strategy involving the development of extra-embryonic membranes that permit either the laying of eggs on land or the retention of the embryos by the mother. Extinct amniotes were initially identified on the basis of skeletal features thought to be unique to Amniota (e.g. presence of an astragalus) but are now identified on the basis of common ancestry. The oldest known amniotes are relatively small forms preserved in the stumps of arborescent lycopods that were major components of tropical rainforests (coal-swamp forests) of the Carboniferous Period. Succeeding Carboniferous amniote remains have been collected from lowland localities of coal swamps and then estuarine localities. Rich amniote faunas of the early Permian are known predominantly from lowland, redbed localities of North America and Europe, apart from a handful of sites that are generally interpreted as preserving upland faunas. Amniotes first emerged as small-bodied, lizard-like insectivores, but by the end of the Carboniferous had evolved into a variety of forms including alligator-sized carnivores and herbivores. Amniotes are known exclusively from paleo-tropical regions until the middle Permian, when they achieved globally widespread distributions.

In this paper further information concerning the ecological and biogeographical aspects of scorpionism is presented. Some of the information already outlined in three previous publications(10,14,16) is assessed, and new data given concerning the pattern of distribution presented by Tityus serrulatus in Brazil. Some new ideas are also proposed regarding the possible evolutionary advantages and disadvantages of parthenogenesis versus sexuality in both the short-term and the long-term.

The belts of savanna lying to the south of the Sahara are described. Evidence is then presented which suggests that these have been created from forest by shifting cultivation and the use of fire: they have probably developed contemporaneously with the evolution of Man and increase in human population. The effect of climatic changes in creating desert are discussed, and the conclusion is reached that present conditions in much of the Sahara have been engendered almost entirely by human activities. These include felling of trees for firewood and charcoal, or to make their leaves accessible to stock in times of drought and, even more important, overgrazing—especially by goats. Finally, it is suggested that, in the long term, agriculture may not be the most promising way of developing arid regions. Overstocking the savanna and desert must inevitably lead to disaster.

Copulation takes place from June until March inclusive but is most frequent between September and November. This is also the season for oviposition, the eggs hatching the following summer. The growth curve of young tortoises shows a close correlation between body weight and length of carapace. Irregularities of the laminae are frequent. These tortoises can survive indefinitely without water if provided with succulent green food. The rate of transpiration in dry air is low: it takes place mainly through the lungs in baby animals but cutaneous transpiration accounts for about half the evaporative water‐loss from older tortoises. A complete water and metabolic balance sheet has been drawn up and an analysis of urine made. Tortoises show behavioural thermoregulation and, if the body temperature reaches40–41°C, copious salivation produces evaporative cooling which prevents any further rise. Reactions to high temperatures are direct and are not mediated through responses to light intensity. There is a well marked temperature‐independent circadian rhythm of activity which is neither accelerated nor retarded by constant light or darkness. Locomotion is stimulated by light and inhibited by darkness, but the phase of the rhythm is not reset by three‐hour periods of light when the animals are kept in darkness not by three‐hour periods of dark when they are kept in light, at whatever hour of the 24‐hour cycle these changes are applied.

A comparison is made of the temperature‐ and water‐relations of the day‐active skink Mabuya quinquetaeniatus and nocturnal gecko Tarentola annularis. In darkness with regularly fluctuating temperatures M. Quinquetaeniatus is active during hot periods, T. annularis when the temperature falls. The lethal temperatures of both species for 24 hours exposure are around 40°C, but T. annularis can withstand a considerably higher degree of desiccation which may be correlated with its comparative lack of mobility. High sand temperatures are not avoided by either species until body temperatures rise. It is postulated that if heat‐death results from physiological oxygen deficiency, as previously suggested, some other cause, such as protein coagulation, must operate simulataneously.

Man and the biology of arid zones , Man and the biology of arid zones , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

The late of water‐Joss from tropical African centipedes ( Rhysida nuda and Ethmostigmus trigonopodus ) and millipedes ( Oxydesmus platycercus and Ophistreptus sp.) is proportional to the saturation deficiency of the atmosphere. These animals therefore resemble forms from temperate and desert regions in this aspect of their physiology. Their nocturnal habits are probably related to their high rate of transpiration. The endogenous 24‐hour rhythm shows a slight retardation in constant light and an acceleration in darkness. The probable function of this is to synchronize it with diurnal environmental changes. The West African scorpion, Pandinus imperator , has a ‘critical temperature’ considerably lower than those of desert species and comparable with that of the Italian Euscorpius germanus . Zusammenfassung UNTERSUCHUNGEN ÜBER DIURNALE RHYTHMEN IX. DIE WASSER‐VERHÄLTNISSE EINIGER NÄCHTLICHER TROPISCHER ARTHROPODEN Bei den tropischen afrikanischen Hundertfüßlern Rhysida nuda und Ethmostigmus trigonopodus , den Tausendfüßlern Oxydesmus platycercus und Ophistreptus sp. sowie bei dem Skorpion Pandinus imperator wurden die Wasserverlustraten durch Wägen der Individuen bestimmt, die über Phosphorpentoxyd in konischen Flaschen aufgehängt wurden, die in ein Wasserbad tauchten. Die Tiere wurden jeder Temperatur 20 Minuten lang ausgesetzt, bevor der durch Evaporation bedingte Betrag des Wasserverlustes bestimmt wurde. Es wird gezeigt, daß diese Methode wertvolle Vergleiche zwischen den verschiedenen Arten zu ziehen gestattet. Sowohl bei Hundertfüßlern wie auch bei Tausendfüßlern erwies sich die Transpiration als proportional zum Sättigungsdefizit der Luft. Diese Tiere ähneln deshalb in diesem Punkte ihrer Physiologie Arten aus gemäßigten und Wüsten‐Gebieten. Ihre nächtliche Lebensweise, die mittels Aktographen festgestellt wurde, steht wahrscheinlich in Beziehung zu der vergleichsweise hohen Wasserverlustrate. Der endogene diurnale Rhythmus zeigt eine leichte Verzögerung bei Dauerbeleuchtung und eine Beschleunigung bei Dunkelheit. Auf diese Weise wird wahrscheinlich die Periodizität dieser Tiere mit dem 24‐Stunden‐Rhythmus der Umgebung synchronisiert. Die kritische Temperatur des westafrikanischen Skorpions Pandinus imperator liegt beträchtlich niedriger als die der Wüsten‐Arten und ähnelt der des italienischen Euscorpius germanus. Es wird vermutet, daß in diesem Falle die nächtliche Lebensweise in Beziehung steht zu der Gefährdung des größen, langsamen Tieres durch räuberische Wirbeltiere. Es wird geschlossen, daß im allgemeinen die Transpirationsrate in Beziehung zum Habitat steht und bei Wüstenbewohnern am niedrigsten ist.

This book was conceived largely at the sink, where most modern husbands have to spend so much of their leisure.My deepest thanks are therefore due

The field cricket, G. campestris, is normally active during the daytime. The 24-hr rhythm of activity and rest persists in constant darkness, its phase being temperature-independent. The internal “clock” system of the insect can be reset by brief exposure to light, or by return to higher temperatures after a period at 5°C. It can be reset by light even when locomotory activity has been suppressed by drought. The suggestion is made that this may be achieved by the synchronization of a number of internal “clocks” whose phase duration is innate.

ABSTRACT Water-loss in Paradesmus gracilis depends upon temperature and humidity, and is directly related to saturation deficiency. There is no evidence of any ‘critical point’ to indicate an epicuticular wax layer. Water is readily lost and taken up through the cuticle, the effect of the spiracles and of excretion being negligible. Despite great sensitivity to desiccation, there is nevertheless some degree of impermeability. The cuticle is in many ways similar to that of an insect: it is composed of a ‘cuticulin’ epicuticle, a ‘tanned’ chitinous exocuticle, and a laminated endocuticle of two optically distinguishable layers. The outer endocuticle is strongly calcified. The cuticle is penetrated by pore canals and the ducts of dermal glands. The latter are concerned with the production of exo- and endocuticle, and the secretion of the polyphenols which tan the protein of the exocuticle. The double hardening is probably a specialized condition of millipedes. Transpiration is almost quadrupled by extraction with hot, but not cold chloroform, as the exocuticle is impregnated with lipoids which reduce permeability. These are secreted by epidermal and dermal gland cells, and pass up the pore canals and gland ducts.

The performance of coastal breakwaters in reducing wave height and energy is an important problem. This paper presents an experimental and numerical investigation of solitary wave interaction with two submerged rectangular obstacles. White light and particle image velocimetry (PIV) techniques were utilized to study the free surface profile of a solitary wave and flow field in an experimental procedure. The PIV test results revealed that two clockwise vortices are generated between and after the two obstacles, and the white light test results showed that three phenomena of wave breaking, crest-crest exchange, and air-water mixing occur in the solitary wave passage over the two obstacles. A transient two-dimensional numerical model was used to study solitary wave interaction with two rectangular obstacles. The numerical model was validated with experimental results in terms of free surface profile, velocity fields, and velocity profiles. Using this model, the effects of obstacles height and distance were investigated. The numerical results showed that when increasing the height of the obstacles, the drag force applied on the obstacles, the strength of vortices, the energy loss, and the height reduction of the solitary wave increased. The presence of the second obstacle and wave breaking occurrence constrain the movement of vortices and cause a negative drag coefficient on the obstacles in some cases. The energy loss, the height reduction of the solitary wave, and the strength of the vortex generated between the obstacles increased as the distance of the obstacles increased up to S/L = 1.5. In contrast, the strength of the vortex generated after the second obstacle was decreased by increasing the distance of two obstacles.

The adaptations of spiders to hot, dry environments are reviewed in the context of a number of headings. These include taxonomy, size, burrowing behaviour and the avoidance of flooding. Physiological adaptations to heat and water loss are described, as well as circadian rhythms of activity, and defence mechanisms encompassing burrowing, crypsis, mimicry, and venoms. Distribution, food supply, and phenology are also discussed. It is concluded that desert spiders belong mainly to two ecological groups. (a) Mygalomorphae and large, long-lived tube-dwelling Lycosidae and Sparassidae (K-selection species). (b) Small, short-lived, nomadic hunting spiders of the families Gnaphosidae, Salticidae and Thomisidae (r-selection species).

Accounts of the colours of desert animals are reviewed. It is concluded that, although pale colours may to some extent alleviate heat stress, the primary function of desert coloration is cryptic—both in offence and defence. Black coloration, on the other hand, has an aposematic function—unless it is found on black sands and lava flows, when it may have a cryptic function. It may also be an evolutionary legacy: if so, it presumably had an adaptive function in the first instance. White may be cryptic on white sand or aposematic on darker substrates. The thermal significance of colour is usually slight.

The transpiration rate of P. jannonei is lower than that of M. pruinosus , and low even compared to that of the desert woodlouse, H. reaumuri of North Africa. Different populations of the same species of woodlouse may have transpiration rates which are related to the xeric nature of their environment, but rapid acclimation in the rate of water‐loss does occur. Both species, however, show quick acclimation to high and low temperature, not only as regards their time of survival in saturated air at 41·5°C (L.T. 50 for exposure of 30 minutes) but also in their metabolic rates.

Galeodes arabs is shown by aktograph experiments to be nocturnal in habit especially in the hot season. It has a low rate of water‐loss by transpiration in dry air. Behaviour responses to enemies and prey are classified as alertness, threat, high intensity threat (accompanied by stridulation) leading to attack or flight (often followed by displacement sand‐digging). Feeding habits are described. RESUME QUELQUES ASPECTS DE LA PHYSIOLOGIE ET DU COMPORTEMENT DE GALEODES ARABS Les moeurs nocturnes, particulièrement durant la saison chaude, des araignées Galeodes arabs ont été montrées par des expériences avec l'actographe. Dans la nature elles passent la journée dans des abris profonds, dont l'ouverture est fermée par un tampon de feuilles mortes. Leur perte en eau par transpiration à Fair sec présente un taux assez bas et elles peuvent survivre à une forte dessiccation. Leurs réactions de comportement vis‐à‐vis des ennemis et des proies sont classées en promptitude, frayeur, frayeur très intense (accompagnée de stridulation) conduisant à l'attaque ou à la fuite (souvent suivie de déplacement avec rejet de sable). Les habitudes alimentaires sont décrites et on montre que la fuite se produit plus facilement chez mâles que chez les femelles.

Previous articleNext article No AccessEvaporative Thermoregulation in TurtlesM. L. Riedesel, J. L. Cloudsley-Thompson, and J. Anne Cloudsley-ThompsonM. L. Riedesel Search for more articles by this author , J. L. Cloudsley-Thompson Search for more articles by this author , and J. Anne Cloudsley-Thompson Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 44, Number 1Jan., 1971 Article DOIhttps://doi.org/10.1086/physzool.44.1.30155549 Views: 8Total views on this site Citations: 19Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). Copyright 1972 The University of ChicagoPDF download Crossref reports the following articles citing this article:Anand K. Mishra, Thomas J. 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R. Morgareidge, H. T. Hammel Evaporative Water Loss in Box Turtles: Effects of Rostral Brainstem and Other Temperatures, Science 187, no.41744174 (Jan 1975): 366–368.https://doi.org/10.1126/science.1111111William G. Voigt Heating and cooling rates and their effects upon heart rate and subcutaneous temperatures in the desert tortoise, gopherus agassizii, Comparative Biochemistry and Physiology Part A: Physiology 52, no.33 (Jan 1975): 527–531.https://doi.org/10.1016/S0300-9629(75)80076-4J.L. Cloudsley-Thompson Physiological thermoregulation in the spurred tortoise ( Testudo graeca L.), Journal of Natural History 8, no.55 (Oct 1974): 577–587.https://doi.org/10.1080/00222937400770491Robert E. Gatten Effects of temperature and activity on aerobic and anaerobic metabolism and heart rate in the turtles Pseudemys scripta and Terrapene ornata, Comparative Biochemistry and Physiology Part A: Physiology 48, no.44 (Aug 1974): 619–648.https://doi.org/10.1016/0300-9629(74)90606-9Edgar C. Lucey Heart rate and physiological thermoregulation in a basking turtle, Pseudemys scripta elegans, Comparative Biochemistry and Physiology Part A: Physiology 48, no.33 (Jul 1974): 471–482.https://doi.org/10.1016/0300-9629(74)90729-4B.A. Sturbaum, M.L. Riedesel Temperature regulation responses of ornate box turtles, Terrapene ornata, to heat, Comparative Biochemistry and Physiology Part A: Physiology 48, no.33 (Jul 1974): 527–538.https://doi.org/10.1016/0300-9629(74)90735-XG.J.W. Webb, Clifford Ray Johnson Head-body temperature differences in turtles, Comparative Biochemistry and Physiology Part A: Physiology 43, no.33 (Nov 1972): 593–611.https://doi.org/10.1016/0300-9629(72)90246-0David C. Spray, Michael L. May Heating and cooling rates in four species of turtles, Comparative Biochemistry and Physiology Part A: Physiology 41, no.33 (Mar 1972): 507–522.https://doi.org/10.1016/0300-9629(72)90009-6

Abstract This paper reviews research published since the Cold Spring Harbor Symposium of 1960 on “Biological clocks”. It is concluded that, despite annual increases in the quantity of research which have appeared since then, knowledge of the fundamental physiology of rhythms has progressed relatively little. Adaptive functions have fared even worse. It is probable that no single explanation of the diurnal vertical migration of plankton will ever be found. There has, however, been further evidence for the rôle of circadian rhythms in relation to physical factors of the terrestrial environment. These include water conservation among invertebrates and thermoregulation in poikilotherms. The interaction of such factors is discussed in relation to photoperiodism. Biotic factors in which rhythmic activities are of importance include reproduction, feeding, escape from enemies and, presumably, competition, although there appears to be little factual evidence for this. Finally there is a discussion of the adaptive significance of seasonal rhythms, especially in the tropics where the advantages they confer are not immediately obvious as in temperate climates. The rôle of “clock” mechanisms in celestial navigation is not considered in this paper. Abstracting keywords: circadianseasonal rhythmsadaptation Notes Dept of Zoology, University of Khartoum, Khartoum, Sudan.

B. regularis Reuss is nocturnally active, having an endogenous rhythm that is not accelerated in darkness or retarded by constant light. The rate of water‐loss is correlated with the saturation deficiency of the air and there is no control of transpiration. Pulmonary ventilation, however, plays a significant part in evaporative cooling. The lethal temperature for one hour's exposure in moist air is 39°C: in dry air a body temperature of 42°C has been recorded from a living toad. There is no correlation between rate of water‐loss and the point at which dehydration becomes lethal. The maximum water‐loss survived is 50% of normal body weight. The rate of water‐uptake is not influenced by ambient air temperature‐it is greatest in toads desiccated below 10 to 15% of original weight and declines as rehydration proceeds.

STUDIES of the physiology and water relations of desert birds have dealt with a few carinate species1, but practically nothing is yet known of the adaptations of the ostrich Struthio camelus L. to hot, dry environments. Because it is large, the ostrich cannot obtain shelter from the rigours of its environment in the manner of smaller birds, but we have found it to possess salt-excretory nasal glands which enable it to utilize saline water. At least one subspecies, S. camelus massaicus, frequents the neighbourhood of salt and soda lakes2. It has been suggested that ostriches can exist on dry or succulent food without needing free water, but no experiments have previously been carried out to confirm this. We are therefore investigating the water economy of S. camelus in the Sudan.

By means of choice‐chamber experiments, Ocnera hispida and, to a lesser extent, Pimelia grandis were shown to exhibit photonegative responses at all temperatures while Adesmia antiqua was photopositive. The intensity of the light reactions of the first two species was not influenced by the temperature, but A. antiqua was more markedly photopositive at higher temperatures. All species respond to near‐lethal temperatures by digging into the sand. Analysis of aktograph records showed that O. hispida and P. grandis are strictly nocturnal, A. antiqua diurnal in habit, The endogenous chronometer in P. grandis is retarded by cold, but is not re‐set. Résumé LES RÉPONSES A LA LUMI***ERE ET LES RHYTHMES DIURNES CHEZ LES TENEBRIONIDES DÉSERTICOLES. Des expériences effectuées au moyen d'une “choice‐chamber” ont démontré que O. hispida et à un degré inférieur P. grandis ont des réponses photonégatives à toutes les températures, tandis que A. antiqua est photonégative. L'intensité des réactions à la lumieGre des deux premieGres espeGces n'a pas été influencée par la température, mais A. antiqua était nettement plus photopositive à des températures plus élevées. Aux températures sublétales toutes les espeGces répondent par un enfouissement dans le sable. L'analyse des données aktographiques a démontré que O. hispida et P. grandis sont rigoureusement nocturnes, tandis que A. antiqua est une espeGce diurne. Le chronomeGtre endogeGne chez P. grandis est retardé par le froid, mais le retard n'est pas rattrapé.

Long-term climatic variations over the past 400,000 years, disclose a cyclical alternation of cold or glacial phases. At the present time, the world is experiencing one of its warmer climatic periods. Nevertheless, summer insolation has decreased sharply during the last 9,000 years and, apart from human influences, a gradual reduction in temperature might well be expected to occur during the next 50,000 years. On the other hand, if the human-induced ‘greenhouse effect’ manifests itself as is sometimes forecast, climatic changes will take place much faster, and temperatures could reach higher levels than in any of the post-Pleistocene interglacial phases. The future of the Sahara depends to a considerable extent upon which of these trends actually manifests itself.

The recent drought in the Sahel savanna is by no means abnormal: it is part of a general drying-up process that took place mainly between 7000 and 3500 years BP. Subsequent impoverishment of the flora and fauna has been due almost entirely to human activities?bad agriculture, felling trees for fuel and overgrazing by domestic stock. Various solutions have been proposed to the problem of desertification, but individually these are either impracticable or unpromising. The best hope for the future lies in multiple land use, the development of run-off agriculture, plant breeding and industrial development.

Journal Article Golden Shadows, Flying Hooves Get access Golden Shadows, Flying Hooves, by George Schaller. Collins, 1974. xxiii+287pp. Illustrated, 3 maps. £3.50. Animals, Environment and Man in Africa, by N. C. Pollock. Heath, 1974. ix+159pp. Illustrated, 16 figures. £4.00. J. L. CLOUDSLEY-THOMPSON J. L. CLOUDSLEY-THOMPSON Birkbeck College, University of London Search for other works by this author on: Oxford Academic Google Scholar African Affairs, Volume 74, Issue 297, October 1975, Page 512, https://doi.org/10.1093/oxfordjournals.afraf.a096673 Published: 01 October 1975

During the late Pleistocene, the Sahara experienced both pluvial and inter‐pluvial periods when the climate was successively wetter and drier than it is today. At the end of the Pleistocene the regions bordering its southern edge were richly supplied with lakes and rivers. These dried up between 7000 and 3500 B.P. as the climate became progressively drier and warmer. Subsequent impoverishment of the flora and fauna has been due almost entirely to human activities: bad agriculture, felling trees for fuel, and overgrazing by domestic stock.

Treating a collection of scorpions from the Ennedi, Kapka and Tibesti mountain massifs in Chad reveals an interesting fauna with several elements possibly endemic to these areas.Nine new species are described: Androctonus pallidus sp.n., Buthacus golovatchisp.n., Butheoloides (s.str.)granulatus sp.n., Buthus hassanini sp.n.,Compsobuthus boucheti sp.n., Hottentotta mateui sp.n., Orthochirus minorsp.n., Orthochirus tibestisp.n.(Buthidae) and Scorpio ennedi sp.n.(Scorpionidae).Biogeographic comments are also added on the scorpion faunas of other Saharan massifs.

Tropical forest and woodland tarantulas, scorpions and scolopendromorph centipedes are much less active than desert forms: they often spend several days completely motionless, and what movement they do show is far less rhythmic than that of desert species. Their locomotory rhythms appear to be influenced more by thermal fluctuations than by alternating light and darkness, unlike the rhythms of their desert-dwelling relations. Whereas the forest and woodland tarantulas show a tendency to be active in light, the scorpions and scolopendras are nocturnal. The possible ecological significance of these observations is discussed.

Summary Evaporative cooling, through moistening of the eyes, panting, urinating and salivating, takes place in the spurred tortoise at high ambient temperatures. The mean temperature at which thermoregulatory salivation is initiated (39·5° ± 0·4°C) is constant, irrespective of body size, but the rate of panting is slower in heavier tortoises. Very small tortoises, however, do not pant for more than a few seconds. Tortoises are inactive at 13°C and their body temperatures do not vary from the ambient. At 21° and 26°C, heat loss through transpiration exceeds metabolic heat production: at 33°C body temperatures are higher than the ambient. Increased range and variability at higher temperatures may be explained by the fact that spurred tortoises hold their breaths for long periods—a mechanism that could serve to reduce respiratory water loss. When breathing is actually taking place, however, the rate of respiration depends on body temperature: this grades into panting above 35°C.

Summary Mean supercooling points are given for a number of tropical arthropods (table 1). These are surprisingly low in view of the fact that, in many cases, the animals never experience frost in nature, and it is argued that the ability to supercool may be a taxonomic rather than an adaptive feature. Beetles (Ocnera hispida) and desert locusts (Schistocerca gregaria) that had been supercooled once, showed a significant reduction in their supercooling points. Migratory locusts (Locusta migratoria) did not do so (table 2). Hydration caused a significant reduction in the supercooling point of S. gregaria but not of L. migratoria (table 3). Starvation lowered, but not significantly, the supercooling point of S. gregaria, and significantly that of Rhodnius prolixus (table 4). Pre-conditioning ('Mellanby effect') has been shown to result in a lowering of the supercooling point, significant in S. gregaria but not in L. migratoria (table 5). This is not achieved by dehydration, the elimination of faeces, an increase in osmolarity or by the secretion of glycerol. It could, however, result from a change in the nature or location of food already in the alimentary canal.

ALTHOUGH reptiles in a laboratory cage may show feeble powers of thermoregulation, it is now known that, when active in natural conditions, their body temperature is often regulated by behavioural means at a thermal level higher than that of many mammals1. Tortoises are no exception and sun themselves when the air is cool. Experiments on young desert tortoises, Testudo sulcata Miller (= T. calcarata Schn.), have shown that water loss by evaporation increases greatly in dry air at temperatures above 40°–41° C. At ambient temperatures of 55° C the body temperature rises rapidly to about 40.5° C, at which level it is maintained by copious salivation which wets the head, neck and front legs. Although they do not usually take water when supplied with green food, these tortoises drink deeply after such experiments.

Water is lost by transpiration at relative humidities (R.H.) as high as 98% at 27° C and there is no evidence of the uptake of moisture through the integument from unsaturated air or moist surfaces. Water‐loss through transpiration is directly related to saturation deficiency and there is no ‘critical’ transitional temperature at which the cuticle becomes porous. Nevertheless, water is retained more efficiently in Scolopendra than it is in Lithobius , suggesting an adaptation to hot‐dry environments. The mean supercooling point of large specimens conditioned in an insectary is —3.1 ± 0.48° and a single supercooling can be injurious or fatal. This indicates that cold winter weather must be avoided by burrowing deeply. Aktograph experiments show that these centipedes are nocturnal. The rhythm persists in darkness at constant temperature, but is quickly lost in constant light. Résumé RÉACTIONS À L'HUMIDITÉ ET À LA TEMPÉRATURE ET RYTHME JOURNALIER CHEZ DES MYRIAPODES SCOLOPENDROMORPHES Les Myriapodes étudiés montrent une perte d'eau par évaporation lorsqu'ils sont placés dans une ambiance à 27° et dont l'humidité relative est de 98%; il n'y a aucune indication permettant de penser que ces arthropodes peuvent se rehydrater à partir des surfaces mouillées ou de l'humidité atmosphérique, par prélèvement à travers leur tégument. La perte d'eau par transpiration est directement en rapport avec la déficience de saturation de l'air et il n'y a aucune température critique de transition pour laquelle la cuticule deviendrait perméable à l'eau. Néanmoins l'eau est retenue plus efficacement par Scolopendra que par Lithobius , ce qui suggère chez le premier genre une adaptation aux milieux chauds et secs. Le point de surfusion mesuré pour de grands spécimens maintenus en insectarium, est en moyenne de —3,1 ± 0,48° et un seul choc à cette température de surfusion peut être préjudiciable ou même fatal. Cela indique que ces arthropodes doivent éviter les froids de l'hiver en creusant plus profondément les galeries. Des expériences utilisant un actographe montrent que ces Myriapodes ont une activité nocturne. Le rythme naturel d'activité persiste à l'obscurité et à une température constante, mais il est rapidement perdu par exposition à un éclairement continu.

Proceedings of the Royal Entomological Society of London. Series A, General EntomologyVolume 37, Issue 1-3 p. 27-34 BIOCLIMATIC OBSERVATIONS IN THE RED SEA HILLS AND COASTAL PLAIN, A MAJOR HABITAT OF THE DESERT LOCUST J. L. CLOUDSLEY-THOMPSON, J. L. CLOUDSLEY-THOMPSON Department of Zoology, University of Khartoum, SudanSearch for more papers by this author J. L. CLOUDSLEY-THOMPSON, J. L. CLOUDSLEY-THOMPSON Department of Zoology, University of Khartoum, SudanSearch for more papers by this author First published: April 1962 https://doi.org/10.1111/j.1365-3032.1962.tb00284.xCitations: 7AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume37, Issue1-3April 1962Pages 27-34 RelatedInformation

Adult giant velvet mites appear in the desert after rain. They are diurnal in habit, but become crepuscular in dry conditions. Their high rate of water‐loss by transpiration suggests that they are not particularly well adapted to drought. They are positively phototactic and negatively geotactic in dry sand, but dig burrows where it is damp. Their scarlet coloration has an aposematic function. Resume QUELQUES ASPECTS DE LA PHYSIOLOGIE ET DU COMPORTEMENT DE DINOTHROMBIUM TINCTORIUM L. ACARI. Les larves Dinothrombium tinctorium L. sont parasites des Locustides. Les adultes apparaissent dans le désert après les pluies annuelles. Ils sont de moeurs diurnes et montrent un maximum d'activité vers 13 heures si le sable dans lequel ils vivent est humide, mais ils deviennent crépusculaires s'il est sec. Leur taux de déshydratation par transpiration est élevé par rapport à celui des tiques de taille comparable, ce qui suggère qu'ils ne sont pas particulièrement bien adaptés aux conditions de sécheresse. Ils sont photopositifs et géonégatifs dans un sol sec. Leur couleur écarlate a une fonction prémonitoire ou aposématique et le tégument présente des canaux de nombreuses glandes dermiques qui secrètent probablement un fluide répulsif.

An account is given of the life history, growth, population densities, habitat, reproductive systems, courtship and mating, litter size and sex ratio, iteroparity, molting and development of the scorpion Chactas reticulatus Kraepelin. These same traits are compared in three distinct scorpion lineages, buthid, chactid and ischnurid in relation to habitat characteristics. Correlations are drawn between reproductive and adaptative strategies, and it is suggested that if non-buthid scorpions may present some homogeneity as equilibrium species, buthid scorpions are not necessarily opportunistic species. Many groups can be characterized within the buthids, and these different lineages show variable ecological requirements.

By means of a simple aktograph consisting of a float attached to a needle writing on a kymograph drum, it has been shown that the Nile crocodile exhibits a weak diurnal rhythm of activity. When the results of several days are averaged the periodicity becomes more apparent, with a peak in the early hours of the evening. The rhythm is less marked in hot than in cooler weather. Crocodiles show a greater tendency to haul out of the water and bask in the sunshine on days when the air temperature lies above about 24 °C than in cooler or hotter weather.

Annals of Applied BiologyVolume 46, Issue 1 p. 117-119 WATER RELATIONS AND DIURNAL RHYTHMS IN WOODLICE J. L. Cloudsley-Thompson, J. L. Cloudsley-Thompson Department of Zoology, King's College, LondonSearch for more papers by this author J. L. Cloudsley-Thompson, J. L. Cloudsley-Thompson Department of Zoology, King's College, LondonSearch for more papers by this author First published: March 1958 https://doi.org/10.1111/j.1744-7348.1958.tb02186.xCitations: 7AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume46, Issue1March 1958Pages 117-119 RelatedInformation

1. (1) The main ecological zones of the area have been outlined. Arachnids are very scarce with the exception of Lycosa tarsalis Thor. and Mitopus morio Fabr. which are particularly abundant in dry...

In constant darkness, the onset of locomotory activity in the nocturnal desert beetle P. grandis free-ran with an advancement of about 1 hour–1 hour 10 min per day despite temperature changes in the range 22.5–16.5°C. Movement was suppressed below 16°C, although the circadian clock continued to free-run. In some instances, a split was observed in the period of activity, after which the two components free-ran with the same frequency.

The vinegaroon or whip scorpion Mastigoproctus giganteus gains water by drinking from a moist substrate and from its prey. These are found by the sensitive antenniform front legs. Large specimens readily lose water to the air at 26° at humidities up to 95% R.H. As temperatures increase they lose water in proportion to the saturation deficit of the atmosphere, suggesting the absence of an epicuticular wax layer. Desiccated vinegaroons respond positively to moist air in a humidity gradient, but show no preference between darkness and light. Substrate moisture does not affect the lack of such a preference by normal animals. Burrowing is characteristic of dehydrated individuals. By using their sensitive front legs these first detect nonhorizontal surfaces and, provided the substrate is moist, dig burrows against – and in nature most likely beneath – such surfaces so that further water loss is presumably avoided. Résumé TRANSPIRATION, RÉACTION Á L'HUMIDITÉ ET COMPORTEMENT ÉVITANT LA DESSICATION, CHEZ MASTIGOPROCTUS GIGANTEUS (ARACHNIDA: UROPYGI) Mastigoproctus giganteus se rencontre dans les régions arides du Sud‐Ouest des U.S.A.; rare pendant la saison sèche, il apparaît après les pluies. C'est un prédateur nocturne, principalement d'insectes. Le présent travail tente de préciser comment cet Arachnide réagit aux conditions d'aridité des régions désertiques. De grands exemplaires vivants de M. giganteus montrent un taux de perte en eau relativement élevé pour une température de 26° avec une humidité relative pouvant aller jusqu'à 95%. Pour ces grands spécimens la transpiration à travers la cuticule s'accroît de façon approximativement linéaire pour les températures supérieures, ce qui indique l'absence probable d'une couche cireuse épicuticulaire fonctionnelle. Des animaux hydratés ne répondent pas à un gradient d'humidité, mais après avoir été soumis à des conditions de dessication les individus de petite taille montrent une préférence marquée pour l'air le plus humide. Ils ne manifestent aucune préférence entre la lumière (1,500 lux) ou l'obscurité lorsqu'ils sont placés sur sable sec ou humide, même après avoir une dessication partielle. La faible aptitude physiologique de ces animaux pour réduire leurs pertes en eau semble compensée par un sens thigmotactique hautement développé qui leur permet d'une part, de capturer aisément leurs proies, d'autre part de détecter des surfaces non‐horizontales contre lesquelles ils creusent alors si le substrat est humide. Ce comportement doit jouer un rôle important en évitant à l'animal les conditions de dessication.

Abstract Maximum locomotory activity in B. minax takes place in darkness when the temperature is rising. These factors entrain the circadian rhythm of the species. A bimodal rhythm, with peaks induced by alternating light and darkness and an increase in temperature during the light period, tends to persist in constant temperature and darkness until a single peak of activity every 24 hrs eventually asserts itself. The rhythm is neither accelerated nor retarded in constant darkness and therefore does not follow the circadian rule.

Biological observations on Chaerilus philippinus were based on specimens from the region of Appari, North of Luzon in the Philippines. The total duration of embryonic development was estimated as being between 110 to 136 days, while the moults between successive juvenile instars and adulthood took place at ages that averaged 7, 39, 73, 190 and 327 days. These developmental periods are shorter and different from those previously observed among species of non-buthid scorpions. They prove to be rather similar to those observed in buthid scorpions, however. Morphometric growth values of the different instars are similar or smaller than those of other species of scorpions that have been studied. Aspects of maternal care and social behaviour are also commented. To cite this article: W.R. Lourenço et al., C. R. Biologies 331 (2008). Des observations biologiques ont été réalisées chez Chaerilus philippinus, pour des spécimens collectés dans la région d'Appari dans le nord de Luzon aux Philippines. La durée totale du développement embryonnaire peut être estimée entre 110 à 136 jours, tandis que les mues nécessaires à l'acquisition des différents stades juvéniles ainsi que le stade adulte ont eu lieu à 7, 39, 73, 190 et 327 jours. Les durées en jours, observées pour le développement de C. philippinus sont globalement différentes et plus courtes que celles observées préalablement pour des espèces de scorpions non-Buthidae, mais très similaires à celles observées pour les espèces de scorpions Buthidae. Les taux de croissance observés pour les différents stades sont soit similaires, soit plus faibles que ceux observés pour d'autres espèces de scorpions. Des commentaires sont également apportés sur les comportements maternel et social. Pour citer cet article : W.R. Lourenço et al., C. R. Biologies 331 (2008).

ALTHOUGH the physiology of the camel, kangaroo-rat, jerboa and various domestic animals of desert regions has been examined in some detail1,2, nothing is known of the heat and water relations of that most typical desert mammal, the gazelle. It has occasionally been suggested that gazelles may be able to live indefinitely on dry food without water, like desert rodents, but no experiments have been made to determine if this is true or whether, like camels, they need to drink. For this reason an investigation of the water economy of the Dorcas gazelle, Gazella dorcas dorcas (L.) is now being pursued here.

Introduction Evolution Convergence and Extinction Locomotory Diversity on the Ground Arboreal, Aerial and Aquatic Locomotion Diversity of Anti-predator Devices Nutritional Diversity Reproductive Diversity and Life Histories Daily and Seasonal Cycles, Hibernation, Aestivation and Migration Thermal Diversity and Temperature Regulation Water Balance and Excretion Relationships with Mankind Bibliography Index.

WITH reference to a previous communication1 in which it was suggested that the colours of Polycelis nigra and Planaria lugubris are due to different depositions of melanin in the skin, the fact that a red intermediate compound is formed in the oxidation of melanin from tyrosine is significant. Pink specimens often occur (8 percent), and a large proportion of the Polycelis cornuta found at Cambridge are pink in colour.

Tityus serrulatus Lutz & Mello 1922 (in fact, the form confluenciata within the Tityus stigmurus complex) is an extremely toxic scorpion of considerable medical importance in Brazil. Its rapid spread is partially due to parthenogenesis. Speculation regarding the occurrence of sexual individuals has been resolved by the discovery of a population, described here, having a male-female sex ratio of 1/2.5. Four color morphs of the T. stigmurus complex are described, and it is concluded that T. serrulatus and Tityus lamottei Lourenco 1981 are junior synonyms ofT. stigmurus (Thorell 1877).

The morphological evolution of a volcano records the main events of its formation, and its complexity is a function of overlapping constructive and destructive phases. Typical morphological evolutionary trends have been established: simple cones grow into larger cones or they widen into sub-cones or massifs. However, there are many exceptions to these general sequences. One exception is represented by Chimpa Volcano, an andesitic stratovolcano located in the Central Puna of the Andes. In order to evaluate the morphological evolution of Chimpa Volcano, its morphology was characterized, analyzed and quantified using a Digital Elevation Model (DEM). Chimpa Volcano is morphologically classified as a sub-cone, and three constructive stages of evolution and one destructive event have been recognized. The current morphology is related to the formation of an elongated depression flanked by scarps, named Quebrada Casana generated by a destructive event. Morphology and stratigraphy were linked using a parameter named emplacement balance (E*) which is defined as the volumetric ratio between the volcanic products emplaced far away from the vent and those which remain near vent. Chimpa Volcano's morphological evolution is directly related to the type of volcanic products emitted. The evolution began with the emission of pyroclastic density currents (PDCs), where E* remains high, favoring the development of a plateau (Stage I). Then lava dome emplacement in a central position and its destruction reduced the value of E* and a massif was created (Stage II). Finally E* reached the lowest value when the volcano began to emit lava flows forming a sub-cone (Stage III). The presented methodology to evaluate volcanic products in relation to their morphology can be applied to other volcanic edifices in the central Andes and elsewhere.

The rhythmic onset of locomotory activity in A. cancellata, a day-active desert beetle, is advanced in darkness and retarded by constant light, in contradiction to the ‘circadian rule’. In alternating light and darkness, activity takes place progressively earlier during the light period when this is being decreased, and even starts before the onset of illumination if the photoperiod is very short. The endogenous clock continues to free-run at temperatures below 10 °C although locomotory activity has been suppressed. The significance of these findings to the ecology of the insect are discussed.

IN a previous communication1 we stated that the Dorcas gazelle Gazella dorcas dorcas (L.) requires water or succulent food in order to maintain homeostasis in desert conditions. It loses weight steadily on a diet of dry sorghum (millet) without water. Feeding ceases when 14–17 per cent of normal body weight has been lost and the animals appear weak and emaciated. This may take up to 12 days under winter conditions at Khartoum when the air temperature ranges between about 10° C (50° F) and 30° C (84° F) with a relative humidity varying from 20 to 40 per cent; but, in summer, when the air temperature fluctuates from about 35° C (95° F) to 45° C (113° F), with a relative humidity varying from 10 to 30 per cent, gazelles cannot survive for more than about 5 days without water. Two experimental animals died after 6 days' water deprivation, during which they lost 24 per cent of their original weight. This contrasts with a loss of 30 per cent which can be tolerated without ill effects by the camel2 and about 12 per cent which can be withstood by man and most other mammals3.

ATTENTION has recently been directed to the close parallel that exists between the rhythm of biting activity in certain East African mosquitoes and the bimodal flight activity of the Trichoptera, and it is suggested that in insects showing abrupt ‘eo-crepuscular’ activity the control is mainly microclimatic1. If this is so, the diurnal rhythm must be largely ‘exogenous’ in nature and would not persist under constant environmental conditions as ‘endogenous’ rhythms do. The majority of animal species, however, show a combination of both types, and such periodicity is designated ‘composite’. This type of rhythm occurs in cockroaches and has recently been shown to have a neurosecretory basis2.

The presence of stridulatory apparatus is demonstrated in all known species of the scorpion genus Rhopalurus. Scanning electron microscope photographs are reproduced and, for the first time, are accompanied by sonograms (spectrograms). The probable aposematic role of sound production in scorpions is discussed.