摘要:

The functional morphology of the male and female organs of reproduction of the Common earwig (Forficula auriculariaL.) are described together with typical examples of the external male genitalia of most sub‐families of the order. Evolutionary trends involve a gradual reduction in the number of penis lobes from two to one; a process which seems to have taken place several times within the Dermaptera. A natural classification of the Dermaptera is suggested in the light of these dat

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05198.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The effects of winter daylengths on the duration of pituitary refractoriness to photostimulation are described.The mallard, as do probably all wild avian species, enters a postnuptial refractory period during which the gonads display no gametogenesis and the anterior pituitary becomes seasonally unresponsive to photostimulation so far as gonadotrophin secretion is concerned. This phase lasts about three months and is an important synchronizer of the breeding cycles.Refractory specimens kept under a summer daylength of 16.5 hours remain unresponsive to photostimulation at a time when birds in their natural environment are emerging from their refractory period. When, however, such birds are subjected to a period of eight hours daylengths there is a shortening of the refractory phase and they display a gonadotrophic response to photostimulation.There is some indication that a phase of winter daylengths is not, however, a necessary pre‐requisite for birds to be capable of emerging from the refractory period and recovering some degree of spermatogenetic activity. Thus, even in some specimens kept under the long photoperiods there were spermatogonia multiplications occurring when the experiment was terminate

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05199.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

A comparison is made of the temperature‐ and water‐relations of the day‐active skinkMabuya quinquetaeniatusand nocturnal geckoTarentola annularis.In darkness with regularly fluctuating temperaturesM. Quinquetaeniatusis active during hot periods,T. annulariswhen the temperature falls. The lethal temperatures of both species for 24 hours exposure are around 40°C, butT. annulariscan 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 simulat

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05200.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

This account is the result of investigations on living and preserved specimens ofPomacea canaliculataas well as preserved specimens ofPila globosa, Turbinicola saxeaandLanistes ovum bangweolicus.Pilids are amphibious prosobranchs with both a lung and a ctenidium in the mantle cavity. The mantle cavity is broad and shallow, and in addition to the normal pallial complex in these there is a highly extensible pallial inhalant siphon on the left of the head, allowing ventilation of the lung under water, and a fold bordering a longitudinal groove to the right of the head, similar to that in viviparids which creates a separate exhalant channel leading to a samll exhalant siphon. the ctenidium is displaced by the lung to the right and its small leaflets are curved so that they overhang the pallial groove. The hypobranchial gland to the right of the ctenidium extends over the wall of the rectum and genital duct along the right side of the groove.Blood is carried to the lung by the extension of the afferent ctenidial vein and drained from it by the efferent ctenidial vein. InPomaceaan additional afferent vein to the floor of the lung is apparently developed by the horizontal division of the efferent ctenidial vein. To maintain an ample supply of blood at high pressure to the respiratory organs the visceral vein leads directly on to the mantle skirt and has lost its connection with the afferent renal vein. This results in a highly vascular mantle skirt so that a large volume of blood would be forced into the heart on retraction of the snail into its shell; to accommodate this a highly extensible ampulla is developed on the anterior aorta within the pericardial cavity.The kidney, like that of other freshwater prosobranchs, is complex and contains an accessory chamber, overlying the posterior part of the mantle cavity, and which appears to be mesodermal in origin. It is much folded and highly vascular, and is supplied by the afferent renal vein and the renal nerve. The epithelium of the chamber excretes some purines other than uric acid as very fine spherules, whereas in the posterior part of the kidney, large concretions containing uric acid are built up. Blood from the anterior chamber drains into the afferent ctenidial vein; the efferent vessel of the posterior chamber is the homologue of the efferent nephridial vein, although the nephridial gland itself is vestigial. The efferent renal vein to the mantle skirt, which is present in other prosobranchs, has lost its connection with the visceral part of the kidney in pilids.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05201.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

A species of the cichlid genusPelmatochromisrecently imported from West Africa has been observed in captivity and was bred several times. Whereas the females of the imported species all looked alike the males differed in respect of two colour patterns:1 the number of eye spots in the tail fin is constant throughout the individual's life but varies between 0 and 5 among different individuals;1 some males always become red on the whole underside of the belly when courting (type 1) others become red on the hind part of the belly only (type 2).There is strong evidence that these differences in coloration are genetically determi

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05202.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The histological changes which occur in the epidermis of snakes during the sloughing cycle have been studied. The results are based mainly on material obtained fromElaphe taeniuraand are supported by observations on material from nine other genera. The sloughing cycle is divided into six stages. The regions of the epidermis and the histological changes occurring in each stage are described. Each region is named and the nomenclature applied is homologized as far as possible with the terminology used by earlier workers. It is suggested that the liberation of the old, outer, keratinized epidermal generation at sloughing is effected by the destruction of a single layer of living cells by the possible protcolytic action of immigrant eosinophil granulocytes.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05203.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The stomach contents of porpoises from Scottish waters were examined primarily to ascertain if these animals prey on salmon. The dominant fish in the food were clupeoids and gadoids with herring and whiting the commonest individual species. The food types were predominantly pelagic in habit and most of the fish eaten appeared to be less than 25 cm in length. No evidence of salmon was found in the stomachs and from a study of the jaws and dentition of the common porpoise it seems unlikely that the animal is able to eat any fish as large as a salmon.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb05204.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY