摘要:

The transpiration rate ofP. jannoneiis lower than that ofM. pruinosus, and low even compared to that of the desert woodlouse,H. reaumuriof 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 ra

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02146.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Five hydrolytic enzymes (acid phosphatase, aryl sulphatase, β‐glucuronidase, N‐acetyl‐β‐glucosaminidase, and non‐specific esterase) have been studied histochemically in the cells of the digestive gland ofMytilus edulis, Helix aspersa, and certain other lamellibranchs and gastropods. All the enzymes studied have basically similar distributions.In the digestive cells, the enzymes occur in cytoplasmic granules which are believed to be primary lysosomes; in vacuoles which contain phagocytosed food material; and in vacuoles containing lipofuscin granules, which are the residues of digestive activity.In the basiphil cells ofM. edulis, most of the enzymes are localized in a few cytoplasmic granules; non‐specific esterase, however, is found throughout the cytoplasm. In the calcium cells ofH. aspersaand the other pulmonate gastropods studied, the enzymes are either in cytoplasmic granules, or distributed diffusely throughout the cytoplasm. Acid phosphatase is also found in the calcium spherules, especially inH. aspersa.In the excretory cells ofH. aspersaand the other pulmonates studied, the enzymes are found in granules in the cytoplasm, and in the lipofuscin granules which lie in the vacuoles o

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02147.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Chemical and physical data from analyses of soil samples of Kalahari Sand deposits in Wankie National Park, Rhodesia, show that salt licks created and used by elephant are characterized by high concentrations of water soluble sodium. Soils with concentrations of calcium, magnesium and potassium in, for instance, termite mounds are used as licks only in regions where soluble sodium is not present in quantity in the soil. Shallow steep‐sided salt licks are dug out by elephants with their forefeet during the dry season. Elephant dung is deposited in large quantities on and near salt licks at that season. A brown colour is present in aqueous extracts of salt‐lick soils and is likely to consist of sodium salts of humic derivatives of elephant faeces or urine. Rainwater gathering in salt licks in the wet season has an equivalent brown colour and a high sodium content. Similar soil regions rich in sodium but not used as licks have no brown colouration in the soil extract. This brown soluble humic derivative may enable the elephant to detect the salt lick by smell. Licks appear to be important in the social life of the elephant populations. The intensity of present usage of salt licks by elephants is leading to localized soil erosion which will eventually result in the filling in of many clay pans with coarser sa

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02148.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Eggs of the Green sea turtle (Chelonia mydas) and the Loggerhead sea turtle (Caretta caretta) were incubated in coral sand or silica sand moistened with distilled water. The eggs and hatchlings were analysed for calcium, magnesium and phosphorus. There was less magnesium but more calcium in the hatchlings than in the original egg contents but this was not influenced by the type of sand used during incubation. The results are interpreted as indicating that the eggshell is the major source of calcium for the developing embryos. The Logger‐head sea turtle shows a greater efficiency in the incorporation of yolk magnesium and phosphorus into the embryo than does the Green sea turtl

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02149.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Injections of the canal system of the pennatulidPteroides griseum(Bohadsch), and the subsequent movements of the dye within the colony, have afforded some information on the direction and relative importance of various water movements in this species. The respiratory role, for example, of these currents is assessed in the light of what is known of the oxygen consumption ofPteroidesand the nature and role of water movements in other pennatulids.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02150.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

New evidence shows thatTilapia galilaea(Artédi) is almost certainly a bi‐parental mouth brooder throughout its range, and that this habit is not confined only to races found in Israel. Previous classification of this species as a maternal brooder in Africa appears to be based on lack of observations; it is the only member of the genus definitely known to be a bi‐parental brooder. The size of the eggs and the development of their adhesive stalk system is intermediate between those of substrate spawners and mouth brooders. Among the latter the adhesive stalk system of the only paternal brooding species is rudimentary but it is entirely absent in the maternal brooding species. The conclusion is drawn that maternal and paternal mouth brooders did not evolve directly from substrate spawners but independently from bi‐parental br

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02151.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

The records of animals caught by two kinds of breakback trap (Reporter and Museum Special) have been analysed to investigate the ways in which the catch of a trap may be selective. The data comprise 1583 individuals belonging to 12 species of small mammal.The Reporter trap tends, in two distinct ways, to catch individuals which are heavier. Firstly, the proportion of the total catch of a given species caught by Reporter increases with the mean weight of the species. Secondly, within each species (with one trivial exception) the individuals caught by Reporter are, on average, heavier, the mean difference being 36%. In both of these respects significant species x trap interactions remain after the effect of species mean weight have been corrected for.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02152.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

A simple scheme is presented to illustrate four possible kinds of locomotory peristalsis in worm‐like animals. The application of this scheme to real animals is discussed. Peristaltic waves may be of constriction or dilatation. A continuous body cavity enables the worm to regulate both speed and direction of travel by controlling the relative tonus of its body wall muscles. Thus peristaltic waves can be used to pump water without causing locomotion.Sabellairrigates its tube by peristaltic swellings but the coelom and intestine are sub‐divided by entire septa. Anatomical and morphological features which allow the shortest, widest segments forming a “piston” to slide down the tube and the narrower elongated segments to grip its walls are considered. In this way the construction of the typical body segment is given a functional explanation.The functions of septa in annelids are di

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02153.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

InSesarma (Geosesarma) perracaeNobili, 1903 the ovigerous females live in burrows containing fresh‐water into which the young are released. The larval life is greatly abbreviated and the larval stages live entirely on stored yolk. The megalopa stage is almost unrecognizabl

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02154.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

During the non‐breeding season the lobules of the mammary glands consist of solid cords of cells which may occasionally be embedded in a pad of fat tissue.During the breeding season some mammary glands can exhibit a tubular grade of organization and can even secrete milk without the intervention of pregnancy. Apparently the stimulus of pregnancy and incubation of an egg in the pouch is generally, but not invariably necessary for development of an alveolar grade of organization. The ducts leading from the lobules to the skin of the areola undergo hypertrophy during the course of lactation.The present work shows that the gestation period is at least 16 days long but evidence in the literature shows it may be as long as 27 days. The incubation period of an egg in the pouch was found to be of the order of 10–10·5 days.A newly‐hatched echidna weighed 378 mg and was 1·47 cm long; it exhibited an egg tooth and the remains of foetal membranes attached to the abdomen. The newly‐hatched had well‐developed olfactory organs including sensory cells in the olfactory epithelium. The alimentary tract exhibited a degree of differentiation consistent with the notion that it could digest milk.The fatty acid composition of the triglyceride fraction of a sample of milk taken just after hatching differed from that of mature milk in that the ratio of the concentration of oleic acid to palmitic acid in the early milk was about unity whereas it was 3·7 in mature milk. A high level of arachidonic acid may be a characteristic of the milk at hatching.Iron was present in a concentration of 8·3 μg/ml in the early milk, and of 43·0 μ/mlg/ml in a sample of mature milk. The regression of the mammary glands from the alveolar to the solid‐cord state is described.Two corpora lutea of pregnancy, taken about 11 and 19 days after egg layin

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1969.tb02155.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY