摘要:

The secretion of the pallial glands is generally held responsible for rock boring inLithophaga lithophaga(L.). The glands do not secrete acid; the pH of the secretion was found to be about 6.5. Histochemical tests showed that the secretion is a neutral mucoprotein with calcium‐binding ability. This finding indicates, that complexing of calcium by the secretion of the pallial glands is the mechanism of chemical boring into calcareous rock inL. lithophag

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01672.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The present paper reports observations from serial sections of five pouch‐young specimens on the early stages of tooth ontogeny in the post‐incisor dentition ofTrichosurus vulpecula.The order of cusp development and calcification for the molariform teeth is recorded and closely resembles that of placentals. Some features concerning the development of the replacing premolar are noted and compared with the conditions observed inSetonix brachyurus, another marsupial. A number of non‐functional cheek teeth are rep

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01673.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The suckling behaviour of Grey seals and Northern elephant seals was investigated. Evidence suggested that in both species it is usual for females and young to select consistently the same suckling partner though certain conditions bring about changes in this behaviour. Instances of inconsistency in both species are described and the conditions that bring this about are discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01674.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

A study of the five British pseudoscorpions, belonging to the family Neobisiidae, is completed by the present work on the external morphology ofMicrocreagris cambridgei(L. Koch) with special reference to chaetotaxy. It is concluded thatM. cambridgeiis more nearly related toRoncus lubricusL. Koch than either is to the genusNeobisiumas represented byN. muscorum(Leach),N. carpenteri(Kew) andN. maritimum(Leach). The presence of a galea on the movable finger of the chelicera ofM. cambridgeiis discussed in relation to its significance as a subfamilial characteristic.Limited quantitative sampling and a Tullgren funnel extraction technique reveal that one generation is produced each year. The breeding season is short, the protonymphs are free‐living and deuto‐ and tritonymphs overwinter to mature the following summer. It is possible that adults breed for at least two years.Le présent travail termine l'étude des modifications morphologiques que subissent les espèces de Pseudoscorpions britanniques, appartenant à la famille des Neobisiidae, au cours du développement post‐embryonnaire qui comporte 4 stades: protonŷmphe, deutonymphe, tritonymphe et adulte. Les résultats obtenus confirment et complètent ce qui a été signale pour:Neobisium muscorum, Neobisium carpenteri, Neobisium maritimumetRoncus lubricus.Les variations numériques de la chaetotaxie, de la trichobothriotaxie ne cachent pas l'existence des stades mais, au contraire, permettent leur distinction avec plus de facilityé. On constate, au cours du développement que si certains caractères (soies fiagellaires, soies coxales, trichobothries etc.) se somplètent à chaque stade, d'autres s'arrětent, se stabilisent (soies céphalothoraciques, soies chélicériennes par exemple) à un stade donné et leur nombre, leur position, ne changent plus.La comparaison des formules chaetotaxiques et des diverses structures montre queMicrocreagris cambridgeiest plus proche desRoncusque desNeobisium.La présence d'une galéa au doigt mobile des chélicères est discutée en tant que caractère sous‐familial.L'étude de la densité des populations de nymphes et d'adultes est faite par prélévements, régulièrement accomplis au cours de plusieurs années en plusieurs stations. On peut admettre l'existence d'une seule génération annuelle e

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01675.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The cuticle ofProneomeniaconsists of a mucoid matrix containing calcareous spicules and is secreted by the mantle epithelium at the base of the ventral (pedal) groove and over the general body surface. Histochemical examination shows the matrix to be composed of a glycoprotein complex with high acid mucopolysaccharide and low protein contents in which tanning plays little part in stabilization.The cuticle of the Aplacophora is tentatively equated with an early mucoid stage in the evolution of the molluscan shell and it is suggested that secretion of additional protein, followed by hardening by quinone‐tanning, are necessary further stages before a calcified shell evolves. The aplacophoran cuticle is compared with that ofAcanthochitona(Polyplacophora) and, although they are similar in many respects, the latter has in addition a discrete inner cuticular layer whichmay act as a semi‐conducting membrane in the deposition of the calcareous plates. The spicules are similar in both groups, each being secreted within a thin cup‐like membrane which exhibits somewhat similar properties to the inner cu

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01676.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

There are two ovaries in each arm and each ovary bears a single oviduct which opens orally at the interradial angle. The ovarian wall consists of three layers: mesothelium, muscular‐connective tissue layer and germinal epithelium. The haemal space between the germinal epithelium and muscular‐connective tissue layer is filled with a PAS positive fluid. It is suggested that this space may provide storage and transportation of nutrient to the germ cells.The oögonium, situated along the germinal epithelium, is distinguished from the surrounding follicle cells by its clear cytoplasm and large nucleus with a single nucleolus. It measures 10 to 15 μ in diameter.The development of primary oöcytes is divided into premeiotic, growth and germinal vesicle migration stages. The distribution of mitochondria seems to indicate the existence of a definite polarity in the young oöcytes; but this soon disappears at the beginning of vitellogenesis. Morphological evidence seems to suggest that some of the yolk granules may be synthesized first in follicle cells and then transferred into the oöcyte. Histochemical tests indicate that the yolk platelet is a carbohydrate‐protein‐lipid complex.The first meiotic division occurs six hours after sperm penetration and the second meiotic division follows two hours later.Monthly measurement of the oöcyte throughout a year indicates a well‐defined annual spawning cycle; however, the growth of an oöcyte from an oögonium to a mature oöcyte requir

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01677.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

An ecological survey of the London Basin of the Thames was undertaken in an attempt to define the limits of distribution of tubificids and to correlate their distribution with the oxygen concentration and the salinity.The oxygen consumption ofTubifex tubifexhas been measured at various oxygen concentrations to define precisely the critical level.Measurements of oxygen consumption at various salinities have also been carried out, since salinity varies considerably over those parts of the estuary where tubificids are found. Salinity tolerance experiments were carried out in an attempt to determine the reason for the downstream limit of London Bridge.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01678.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Oculotrema hippopotamiStunkard parasitizes the eye of the hippopotamus and is the only monogenean known from a mammalian host. Eggs from the uterus ofO. hippopotamihatch in water in about 30 days at 24 to 26°C. The ciliated larva resembles the larvae of other polystomatid monogeneans, apart from the absence of hamuli and the unequal lengths of the two intestinal caeca.Up to 62 eggs are stored within the uterus of the mature worm. They are not expelled when the worm is transferred from the eye of the hippopotamus to a tube of water. Development starts when the eggs are placed in fresh‐water. There is no development in saline, and no evidence to suggest that larvae developin situaround the eye, although very small worms have been collected from this si

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01679.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Oculotrema hippopotamiStunkard is a monogenean that is found around the nictitating membrane and under the eyelids of the hippopotamus. When specimens ofO. hippopotamiwere collected from both eyes of 42 hippopotamuses in Uganda, 90.5% of the hippopotamuses were found to be infested. The maximum number of parasites on one hippopotamus was 41, and the mean number of parasites per hippopotamus was 8.26. The frequency distribution did not follow a Poisson distribution and is therefore considered to be non‐random. Both mature and small immature worms were found in the same eye, therefore the infection does not immediately confer immunity on the hos

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01680.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Information on the pineal blood system of lizards is very limited. In view of a number of recent suggestions that the pineal complex may function in the secretion and/or storage of hormonal material it was considered necessary to obtain further information on the vascular pathways associated with it. A description is provided here of the pineal circulation inLacerta muralis.This circulation is extensive and provides both an efficient supply to, and drainage from, all parts of the pineal complex. In particular there is an extensive capillary system draining the habenular, posterior, and subcommissural regions. The differences observed between the pineal venous systems ofLacerta muralis, Lacerta viridis, Chalcides tridactylus, Agama cyanogaster, andVaranus niloticusare also recorded. Such differences are restricted to the drainage systems associated with the dorsal sac and anterior wall of the epiphysis. It is concluded that the abundant pineal vascular system would provide a suitable pathway for removing secretory material from the pineal complex.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb01681.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY