摘要:

A new species of terrestrial planarian from Madeira,Kontikia bulbosasp. nov., is described. The genusKontikiais redefined and its scope and status reviewed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05069.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The morphology, histology and ultrastructure of the mesenteric and proctodaeal components of the mixed segment are described in detail, together with the disposition of the associated gut musculature, the patterns of peristalsis and the streaming movements of soil particles in the gut lumen. The mesenteric epithelium is characterized by very extensive basal infoldings which are associated with a large population of mitochondria, but evidence of significant protein synthesis and secretion is lacking. It is proposed that this tissue is a transporting epithelium whose major function is the secretion of a copious, K+‐rich fluid into the intestinal lumen to irrigate the hindgut (proctodaeum) and that alkaline hydrolysis of humic fractions by this fluid is an essential component of digestion.Malpighian tubules are present, but do not participate in fluid excretion. Since the hind‐guts of soil‐feeding termites are exceptionally voluminous and elongated and the major symbiotic micro‐organisms occupy fixed positions by virtue of their attachment to the lining cuticle, it is argued that flushing is necessary to sustain microbial activity and for the recovery of end‐products by the host. A survey of the protodaeal epithelium suggests that the anterior colon (P4a) is the most likely site of fluid reabsorption and that the wall of the hindgut anterior to this site is impermeable. The greater degree of ultrastructural differentiation of the mixed segment ofCubitermes severusand its more complete morphological separation from the midgut suggests that this species is a more advanced soil‐feeder thanProcubitermes

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05070.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

This paper describes the locomotion of salps by jet propulsion, from a combination of measurements of chamber pressures, static thrust, and electromyographic activity, with kinematic records of free‐swimming and tethered salps. From such measurements, estimates are made of the thrust exerted, the drag incurred, and the work performed by single salps, and by chains of linked individuals. It is concluded that salp jet propulsion is a more economical process than is jet propulsion in other animal

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05071.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The ultrastructure of the ventricular endocardial cells in 17 bony‐fish species representing eight families, is described. In species of Characidae, Cobitidae, Cyprinidae, and Gyrinocheilidae these cells are flat (1–2 µm at nucleus) and contain numerous ribosomes, some few bristle‐coated vesicles (BCV) and small (0.243 pm) electron dense inclusion bodies. However, in species of Cichlidae, Gadidae, and Poeciliidae most endocardial cells appear relatively thicker (2–5 µm at nucleus) and contain numerous BCV, tubules of agranular endoplasmic reticulum, and large (0.5‐1.5 µm) moderately electron dense bodies (MDB). In the MDB occur a number of small (20–150 nm) electron dense granules. Within the family Anabantidae, most endocardial cells seem to be of the first type inColisa laliuandTrichogaster leeri.whereas inHelosioma iemminckithere are numerous cells of the second type. When glutaraldehyde/tannic acid fixed heart tissue ofPollachius virensis treated with ferrous chloride, ferric chloride, or osmium tetroxide, and grid stained by uranyl and lead solutions, damaged endocardial cells appear highly electron dense, whereas undamaged ones are electron lucent. Further, when glutaraldehyde fixed tissue is treated with osmium tetroxide/potassium ferrocyanide the subendocardial space is filled by a highly electron dense material. The methods described in this study make it possible to distinguish between those endocardial vacuoles having structural contact with the cell membrane, and those lacking such contact, and also to determine whether the lumen of the former is continuous with the subendocardial space, or with the intertr

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05072.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Spermatogenesis inRana esculentais initiated during metamorphic climax and mature spermatozoa are present in froglets 45 days old. Cytological analysis of cell populations shows that some of the primary spermatogonia may lie dormant for brief intervals of time. Timing analysis of the process of spermatogenesis, in adults and in developing Frog larvae maintained at approximately 18°C, was investigated by different methods. The results are remarkably similar. Although perfect synchrony of the developing cells within a single germinal cyst is not the rule, a uniform rate of advancement of germinal cysts of the same stage of development, in most of the seminiferous tubules of a testis is evident. The duration of the secondary spermatogonial divisions is five to six days, involving five or six mitotic cycles, each cycle lasting approximately 24 h. The premeiotic S‐phase, and phases of leptotene, zygotene, pachytene, diplotene+secondary spermatocytes, and spermiogenesis each have a duration, respectively, of six, two, six, twelve, two and seven days. The duration of spermatogenesis, from a “committed” primary spermatogonium to the formation of spermatozoa is 4

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05073.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

From analysis of ciné film, combined with ultrastructural observations, the anterior feeding structures and their behaviour in the free‐living microbivorous nematodeCaenorhabditis elegansduring ingestion in dense and sparse suspensions ofEscherichia coliare described In dense suspensions bacteria accumulate in the buccal cavity against the three metastomal flaps that nearly close it, and are then swallowed down the three tubular apical expansions of the triradiate oesophageal lumen when the flaps open. Excess medium is then expelled, as the oesophageal lumen closes and traps the swallowed bacteria. The flaps and oesophagus operate by contractions in the seven most anterior oesophageal muscle cells, probably coordinatedviaproprioceptive nerve endings between the cells. About one million nematode hours are needed to extract 1 g of bacteria from 30 ml of medium. With few or no bacteria, the head moves more, the metastomal flaps do not close and medium seems to pass in and out of the buccal cavity, probably as part of the widespread exploration phase of food‐finding behaviour. Abnormal feeding behaviour, control and functions of the metastomal flaps and associated structures, and control of food intake volume are discu

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05074.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Spring behaviour, dispersal and population changes were studied in two populations of individually marked Red‐legged partridges.Young males took up home ranges close to their natal site but young females dispersed away. The incidence of agonistic behaviour between males, the extent of the spring decline in population density and the distance dispersed by males between the winter and breeding ranges were less in an area with more abundant nesting cover.Half the neighbours of a typical male came from the same winter social group. These groups were based on family parties. Males from the same winter group showed less frequent agonistic behaviour to each other and had more overlapped home ranges than those from different group

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05075.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05076.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05077.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The level of fat reserves of an animal gives a good indication of body condition. Riney (1955) who studied various methods of evaluating condition in Red deer in New Zealand considered that fat was deposited in a pre‐determined sequence over the range of body weight studied, which had been described earlier by Hammond (1932) as a general sequence in farm animals. Fat was deposited firstly in the bone marrow, then around the kidney, and finally subcutaneously. He concluded that kidney fat, expressed as a percentage of kidney weight, was the best index of condition as it embraced almost the entire range of physical condition. However, several authors have noted that small areas of fat are found around the kidneys of starved animals with marrow fat percentages<80% (Ransom, 1965; Brooks, Hanks&Ludbrook, 1977; Anderson, Medin&Bowden, 1972). This means that values for kidney fat index of below<40% may not be reliable, as another fat store, the marrow fat is depleted in parallel with it and not after it as Riney (1955) suggested. The relationship between kidney fat index and marrow fat at low levels of kidney fat index has been shown for White tailed deerOdocoileus virginianus(Ransom, 1963, ElandTaurotragus oryx, Impala(Aepyceros melampus)and Cape buffalo(Syncerus caffer)Brookset al., 1977 and Mule deer0. hemionus(Trainer, Hartmann&Kistner, 1979) but has never been shown for Red deer. The aim of this study was to accomplish thi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05078.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY