摘要:

The connective tissues of a wide range of invertebrates have been investigated using a potassium permanganate/spirit blue staining technique. The method demonstrates fibres which are distinct from collagen, vertebrate elastic fibres, and reticular fibres. The fibres are variously associated with subepidermal collagen, muscles, basement membrances, the walls of blood vessels and the sheaths around nerve cords; the method also gives a positive reaction with the arborescent mesogloeal fibres of medusoid coelenterates. Their electron microscope appearance is distinctive and they exhibit a physical elasticity. Chemical tests indicate that following pretreatment with acidified potassium permanganate they show many, although not all, of the properties of vertebrate “elastin”. It is concluded that they should be regarded as a special category of “elastic

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01633.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The cytology of the interstitial cells of the testis of the river lamprey has been studied from the autumn when the upstream migration begins up to the completion of sexual maturation in the following spring. In the early stages of spermatogenesis the interstitial tissue consists of isolated interlobular connective tissue cells. During the winter these appear to increase in numbers and form compact groups sometimes showing an acinar type of structure. In the earlier stages of the secretory cycle the cytoplasm contains small osmiophilic and sudanophilic granules, which appear to aggregate to form much larger lipid positive masses. In the later stages of spermatogenesis in early spring, the interstitium accumulates large areas of lipid and cholesterol positive droplets and in fixed material the cytoplasm shows extensive vacuolization. In the terminal stages the cells undergo complete disintegration. It seems probable that the stage when the interstitium shows masses of lipid and cholesterol positive droplets represents a phase of degeneration and that the secretion of hormone occurs in earlier stages. No convincing evidence has been obtained for the presence of the enzyme steroid‐3β‐ol‐dehydrogenase during the later stages of the secretory cycle. There is evidence that following the degeneration of the interstitium there may be a replacement of the secretory tissue by the transformation of residual connective tissue elements, which may then re‐enter the secretory phase. The changes in the interstitium are paralleled by hypertrophy and evidence of lipid metabolism in the modified fibroblasts of the lobular wall and this tissue may also be involved in the secretory activity of th

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01634.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The venous system ofPolypterusexhibits general asymmetry. The features that characterize the venous system of this peculiarly African fish are the possession of many blood sinuses, the segmental drainage of blood, the continuation of the posterior cardinal veins as separated vessels and the occurrence of several anastomozes between the latter.In the absence of any recent comprehensive work on the blood system of this fish, it was thought that investigation of the circulatory system ofPolypteruswould be valuable. In this paper attention is drawn to Budgettapos;s (1902) original work on a larva ofPolypterus senegalus.Contrary to Budgettapos;s findings it is concluded that what he called the “interrenal” vein is in fact the right posterior cardinal vein. It is also found that paired posterior cardinal veins exist in all adu

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01635.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The gonad ofMonopterus albusundergoes cyclical changes after the reversal of sex from female to male. The seasonally variable events include a prenuptial accumulation of cholesterol‐positive lipid droplets in the cytoplasm of the interstitial cells when spermatogenetic activity is resumed in late February and early March. The development of the interstitial Leydig cells reaches a maximum in May just before spawning. There occurs a sudden depletion of the interstitial lipids during the breeding season in June at a time when the male animals exhibit active nuptial behaviour. After spermiation, the old interstitial cells degenerate, and during the succeeding phase of gonadal inactivity, become replaced by a new generation from connective tissue cells in the interstitium of the gonadal lamellae which gradually accumulate lipoidal material.The lobular cycle comprises a postnuptial accumulation of amorphous intralobular lipids which become completely cleared in February when active spermatogenesis is restored. Spermatogenesis resumes shortly after spawning, but only advances as far as primary spermatocytes during the postnuptial period of inactivity.The authors conclude that, as far as the seasonal variations in gonadal lipid distribution is concerned, the cycles in the gonad of the hermaphroditic teleost,M. albus, conform to the same pattern as those of the gonochoristic seasonal breeders studie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01636.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

B. regularisReuss 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 rehydrati

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01637.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Laboratory measurements indicate that observed differences in the rate of water‐loss from inactiveHelix aspersa, Otala lacteaandSphincterochila boissieriare due to morphological adaptations such as a thicker shell, reduced aperture and thicker epiphragm. These modifications enable terrestrial snails to inhabit dryer environments by increasing the length of time the snail can remain inactiv

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01638.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Investigations have been carried out, both in the field and in the laboratory, into certain aspects of the biology of three species of millipede (Spirostreptus assiniensis, Oxydesmus sp., and Habrodesmus falx) which commonly occur during the rainy season in the Ibadan area of Western Nigeria. The feeding, mating, egg‐laying, and moulting habits of the three species are described. A detailed description is given of the nest‐building habit of the larvae ofOxydesmussp. The elaborate nests which are built primarily for moulting also protect the larvae during the dry season when moisture conditions become unfavourable. Swarming behaviour, uncommon in millipedes, is shown by the larvae ofH. falx. This behaviour which appears to be of survival value to the species is descri

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01639.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The genusStuhlmanniaMichaelsen 1890 (Pareudrilinae, Eudrilidae) is redefined and a key to species given in the light of the author's examination of material of 24 of the 25 species previously recognized. A discussion of the general morphology of the genus is also included. Twenty‐two species are retained and five subspecies ofS. variablisare defined. New and suspected synonyms are tabulated. New records are given ofS. asymmetricaMichaelsen, 1903a,S. Suctoria(Stephenson), 1932, andS. variabilisMichaelsen, 1890, but these include no significant extension of previously known distribution. A map of the distribution of all known species shows that the genus is limited to tropical Africa, with the great majority of species in east and central Africa within 15 degrees of the equator.S. variabilis, one of the most abundant and widespread limnic magadriles in East Africa, is geographically replaced by closely related species in neighbouring regions, viz.S. asmmetricain Ethiopia, andS. inermisaround Lake Tanganyika. These species, withS. gracilis, which occurs at the western extremity of the range ofvariabilis,form a remarkably homogeneous and discrete group on the grounds of somatic and genital characteristics. Thevariabilisgroup, which has the ovaries enclosed in a complex female apparatus which ensures internal fertilization, would require separation as a distinct genus were it not apparently linked to other members of the genus by intermediate forms. The series which can be distinguished in the progressive complication of the female genital apparatus in the genus endorses union ofplatydrilusMichaelsen, 1891, withStuhlmanniaby Michaelsen (1936). Diagrams of this series are given and the significane is discussed of the development of a communication between the spermatheca and the oviduct and enclosure of the ovaries in the system thus produced. Evidence is presented for internal fertilization in thevariabilisgroup and in at least some other species of the genus. The hypothesis advanced by Stephenson, (1930a), that the unenclosed condition of the ovaries and absence of a communication between the spermatheca and oviducts are secondary conditions, and his acceptance of a megascolecid origin of the Eudrilidae, are not supported by the present stud

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01640.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

An up‐to‐date pedigree is provided for the white tigers of Rewa, and it is pointed out that the hypothesis that the characteristics “white” are determined by an autosomal recessive gene “w”, is consistent with the known pedigree. Suggestions are made regarding fut

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01641.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY