摘要:

The accessory glands of reproduction of male Fallow deer (Dama damaL.) comprise paired ampullae which are expansions of the caudal portions of the vas deferens, paired seminal vesicles, a prostate and a disseminate prostate embedded in the pelvic urethra. All the glands undergo an annual cycle of growth and regression, reaching their maximum development in October at the time of the rut. Parallel changes were observed in the testes.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03962.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Energy requirements for growth and maintenance of nestling House martins was studied in relation to brood size and age. Parallel studies of feeding rates and faecal output were made. The effect of mutual insulation between members of the brood on metabolism was of significance for reducing maintenance energy requirements. Of great value for predicting the peak energy demand of the brood was the number of young and their individual requirements for growth and maintenance at different ages. Power equations are given for predicting brood assimilation, faecal output and feeding frequency in relation to brood size. The impact of food scarcity on growth patterns was assessed. The large lipid stores of nestlings served as an energy reserve during adverse conditions both before and after fledging. Asynchronous hatching in large broods is interpreted as a mechanism which serves to minimize the peak in energy demand which occurs about 12 days after the brood hatches.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03963.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Measurements have been made of the principal leg bones of 37 species representing almost the full range of sizes of terrestrial mammals. The lengths of corresponding bones tend to be proportional to (body mass)0·35and the diameters to (body mass)0·36, except in the family Bovidae in which the exponents for length are much nearer the value of 0·25 predicted by McMahon's (1973) theory of elastic similarity. Comparisons are made between mammals of similar size belonging to different orde

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03964.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Material representing the nine currently recognized species ofPogonomysand its subgenusChiruromyswas subjected to a programme of canonical correlation analysis. Results indicated that six of these species were distinct while two other groups merited subspecific rank. The holotype of another species,P. mollipilosus, appeared to bear little relation to the widespread montane rats with which it has customarily been associated and is now included in the synonomy of a lowland species,P. macrourus. Computer analysis did not suggest any close relationship betweenChiruromysandPogonomysandChiruromysis now regarded as a separate genus. Examination of the chromosomes confirms that the division into two genera is valid and, while the karyotype of one could be derived from the other it could just as easily be derived from an independent ancestor. Therefore we postulate an independent origin forChiruromysandPogonomys.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03965.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Studies of spatial arrangement in small mammal populations are usually based on the results of live‐trapping, which is recognized as limiting in an investigation of this sort. The present paper examines the feasibility of two alternative methods using a population ofMicrotus agrestisas the test cas

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03966.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The oxynoaceanVolvatellaand the less well knownAscobullaandCylindrobullaare the most primitive living members of the gastropod order Sacoglossa.Volvatellais a world‐wide genus characterized by a capacious shell into which complete retraction is possible, a posterior exhalant spout‐like pallial siphon, and a sacoglossan radula.At Strandfontein near the Cape of Good Hope, large numbers of these small molluscs were found living among and feeding upon the roots of the algaCaulerpa filiformis, which forms sublittoral meadows on the coasts of southern Africa. They were identified asVolvatella lagunculaSowerby, 1894, originally described (from the shell alone) in material from Port Elizabeth. The mollusc lives and feeds in the muddy sand aroundCaulerparoots at a depth of 5 cm or more below the surface. The captured material proved to be hermaphrodite, sexually mature and to have mated, but no spawn was found. An interesting feature of the reproductive organs was an epidermal ciliated gutter extending along the right flank from the female opening past the male opening on to the side of the head; this is interpreted as an oviducal groove conducting the egg‐stream during oviposition (as has been suggested for the Japanese juliaceans). A similar groove was found on the left side but its function is unknown.The mantle cavity contained a plicate gill; irrigation was brought about by adduction movements which rhythmically deformed the outer lip of the shell. A strong transverse muscle was present and was responsible for these movements. It is evidently homologous with the adductor muscle of the bivalved juliaceans. It is likely that what is pumped through the mantle cavity ofVolvatellais an ooze of fine mud.Volvatella, together withCylindrobullaandAscobulla, constitutes a link between the infaunal proto‐opisthobranchs and the present‐day epifaunal herbivorous Sacoglossa.An annotated list of the world's species ofVolvatellaconcludes

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03967.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The adaptation to coloured backgrounds of green and permanentiy brown specimens ofRana esculenta,and the anatomical and physical bases for their difference in colour were studied by means of reflectance microspectrophotometry and electron microscopy.Adaptation to the lightness of the background took place in the green type, but not in the brown, whereas adaptation to hue and purity in both types seems negligible.The iridophores of this species probably represent a λ/4‐system. The colour difference between the two types seems mainly to be caused by a difference in the selective reflectivity of the iridophores because of a difference in thickness of the platelets and the cytoplasmic interspaces. Furthermore there is a difference in the amount and, probably, composition of the xanthophore pigme

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03968.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Structural adaptations of the branchial apparatus ofHolthuisana(formerlyParathelphusa)transversa(Martens) for bimodal gas exchange and ion uptake are described using optical and electron microscopy.A single epithelial cell type (besides pillar cells) in the gill lamellae fulfils the dual role of ion uptake from freshwater and aquatic gas exchange. The total blood/water distance is about 5–8 μm (cuticle 2–3 μm, cells 2–5 μrn). Apical cellular extensions delimit an extensive system of subcuticular spaces. Mitochondria are numerous in the sub‐apical cytoplasm but do not form “mitochondrial pumps” with the weakly developed basal infoldings. Nephrocytes are present in the gill shaft but not in the lamellae. Each gill possesses two arteries termedepibranchialandhypobranchialarteries), which run parallel and medial to the main afferent and efferent vessels, and which branch extensively in each lamella (lamellar arteries). The multi‐layered endothelial wall of the arteries forms a longitudinally pleated intima. Larger arteries possess an external collagenous sheath. Sheath and intima are absent from the terminal capillaries. It is suggested that the arteries supply oxygen to the metabolically active tissues of collapsed gills during aerial respiration.The branchiostegites are expanded to form lungs which are ventilated by a unique tidal mechanism involving lateral movements of the thoracic wall. The inner cuticular lining of the branchiostegite is smooth and the epidermal cells extremely attenuated. The total blood/ gas distance is only 250–300 nm (cuticle 200–250 nm, epidermal cell extensions 20–50 nm, basal lamina 30–40 nm) and comparable with the lungs of higher vertebrates. Deoxygenated systemic blood is directed close to the gas exchange surface by newly‐describedfimbriated cellsbordering the connective tissue partitions separating fine afferent and efferent blood sinuses.The observations are discussed in detail in relation to general features of the structure of crustacean gills, branchiostegites and permeable cuticles and of crustacean circulatory

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03969.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Mice living in tussock grass on a remote headland of the South Atlantic island of South Georgia (54°S) where the mean temperature is less than 2°C and the monthly average below 0°C for four months each year have been studied. They are big animals (although not as large as those on some North Atlantic islands) and have much brown fat, showing their response to their cold environment. Only two out of 27 gene loci scored electrophoretically were segregating (3·4% heterozygosity); these (Es‐6, Got‐2) are four cross‐over units apart on chromosome 8, and were in strong linkage disequilibrium. There were marked changes in allele frequencies with age which go in opposite directions in males and females, showing the action of stabilizing selection:Es‐6aincreased from 16% in males of less than three months, to 35% in older animals; it declined in females fro

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03970.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Serum thyroxine (T4) and triiodothyronine (T3) levels were higher in neonate seals compared with adults. The appearance of the thyroid gland in neonates was markedly variable but in both neonate and adult Harp seals the thyroid appeared relatively inactive except in one of the specimens examined. The data suggest that the different hormone levels in adult and neonate represent the respective euthroid state for Harp seals at these stages in their life.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb03971.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY