摘要:

The form and function of the reproductive system in the New Zealand sacoglossanElysia maoriaPowell is described and compared with the reproductive systems of other members of the suborder Elysiacea.E. maoriahas numerous gonadial follicles lying in the parapodia. Sperm‐producing and ova‐producing follicles are distinct and in definite zones. Above them are the diffuse and branched prostate glands, and below them are the reticulate albumen glands. Multiple bursal sacs lie in two or more pairs near the centre of the body. There are two genital apertures and no vagina. Male reproductive structures mature, and male reproductive behaviour begins, before female. Full sexual maturity is reached when an animal is about 20 millimetres long.Impregnation is hypodermic, the penis of one animal being thrust apparently into the haemocoele of its partner. Most insertions were at the posterior end of the body. The method of penial penetration is uncertain, for the penis in this species, unlike that in other Elysiacea in which hypodermic impregnation occurs, bears no hollow spine. The fate of sperm at copulation is not known. In spawning the ova pass to the exterior through the glandular oviduct where they receive an albumen coat and a membrane and are bound into a ribbon by two mucous coats. The spawn bands, which are flat white coils attached to the green alga on which the animals live, hatch about two weeks after spawning. Larvae kept in the laboratory showed no tendency to settle after two weeks, suggesting that the planktonic stage may be fairly long.Comparison with other Elysiacea shows E. maoria to be one of the primitive members of the suborder, with its very diffuse reproductive system, large number of small eggs, and long planktonic st

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03869.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

A report is made of field observations during a period of three months on the development, daily activities, and feeding behaviour of eleven grasshopper species found at one location in the Rukwa Valley, Tanganyika.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03870.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The detailed arrangement of the setae is more or less distinctive in nine British species ofSpirorbis,includingS. cuneatussp. n.The genus, which now contains about sixty‐four species, haa been briefly reviewed. To judge from numbers of thoracic segments, method of incubation and larval characters, S. malardi and S. spirillum may be regarded as perhaps more primitive than most British forms andS. pagenstecheri aa more advanced. The abdominal setation is more asymmetrical in these apparently primitive species and least so in the advanced on

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03871.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The reproductive systems and reproductive processes of the maldanidsClymenella torquata(Leidy) andCaesicirrus neglectusArwidsson are described and compared. The sexes show no differences in external features, though investigations suggest that males are smaller than females of the same age. The sex ratio inClymenellais 1:1 and both sexes become mature in their first year. The average ratio inCaesicirrus,calculated over four seasons, is 1 male: 4–2 females, and the worms do not mature earlier than their second year.The gonads lie round the blood vessels associated with tho nephridia, in the anterior region of the trunk. Immature gametes are shed into the coelom where they undergo the early stages of gametogenesis, and become primary gametocytes. The breeding season is restricted to one or two days, immediately following a spring tide, in mid‐May in Clymenella, and in late July in Caesicirrus. The nephridia act as gonoclucts. At this time, the primary oocytes are extruded into the tube, in which confined space they complete certain processes which render them fertilizable. These involve a marked reduction in diameter (of about one‐third), a change in shape from flat to spherical, and the extrusion of a substance, a process which seems t o be necessary before normal cleavage can occur. The sperm of Clymenella are formed in the coelom and are free when shed, but in Caesicirrus discs of primary spermatocytes are shed, and these complete maturation in the confines of the tube after about seven hours. Both eggs and sperm are extruded at the mouth of the tube just before, or during low tide.An attempt is made to relate the difficulties of effecting successful artificial fertilization in these and other polychaetes to the exudation of material From the oocyte while it is still in the tube.The occurrence of hermaphrodite Caesicirrus at Whitstable is desc

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03872.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The nematode cuticle is shown to consist, grossly, of three layers; an outer layer—the cortical layer, an intermediate layerMdashthe matrix layer and an inner layerMdashthe basal layer. With these layers is associated a punctation canal component. The cortical layer carries externally a wholly sclerotized layerMdashthe epi‐cortex. The inner part of the basal layer is modified as a basal lamella for the attachment of the hypodermis, from which it is not sharply delimited, and the body musculature. The punctation canal component is most prominent in members of the Chromadorida where it is responsible for all the punctation patterns characteristic of this Order. The system consists of columnar elements in the simplest forms, for example in the Cyatholaimidae, and a series of interlocking transversely fused units in the more complex, for exampleEuchromadora.In the Desmodoridae and similar “annulate” forms, the punctation canal component forms the major part of the cuticle and appears to be produced by the transverse fusion of punctation canals. In these groups the gross structure of the cuticle is easily established and it is demonstrated that the same system of layering can be identified throughout the Nematoda. It is shown that all modifications of the cuticle can be interpreted as based on and built around a system of punctation canals. The functional requirements of the nematode body are considered and it is demonstrated that the cuticular modifications are developed to meet the necessity for an anisometric cuticle which is flexible longitudinally and strong radially. Thus, the annulate cuticle of the desmodorids and the strongly patterned cuticle ofEuchromadorahave been developed to meet the functional demands which have been met in forms such asAscaris, Enoplus, MermisandDorylaimusby the development of a series of spirally arranged fibre layers. In many forms thematrix layer is plasticMdashthat is, easily distortedMdashwhile the cortical and basal layers are fairly rigid although probably elastic. The high degree of organization of the cuticle is shown not only by the massive elaboration occurring in some forms but also by the birefringence of many of the modified component layers. It is argued that the prominent amphids occurring in many of the free‐living marine forms act as mechano‐stretch receptors. The suggestion is advanced that the punctation canal system evolved originally as a method of allowing the cuticle to grow by the incorporation of additional materials from processes of the hypodermis and it was only later that it became the basis for the many modifications of the cuticle and probably for moulting. The inevitable consequences of the hydrostatic‐skeleton: longitudinal muscle system on the nematode body form are discussed and it is stressed that most of the characters considered diagnostic of the Nematoda are functionally determined. Attention is drawn to the opportunities which must result for convergence during the evolution of the group and the difficulties which this introduces in attempting to classify

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03873.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The accuracy of the multivariate discriminant function is tested in a series ofColobus badius preussiskulls of known sex: it is shown to be valid for non‐human primate material and superior to other metrical methods of sex determinatio

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03874.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Plecotus austriacus(Fischer) is recorded from England on the basis of a single old specimen from Hampshire in the British Museum (Natural History). Other specimens, previously determined asP. auritus,are recorded from Jersey, Channel Islands andseveral other European localities. A summary is given of the principal diagnostic characters of the two species.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03875.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The clinical signs, diagnosis and treatment of a skeletal disease in New World Primates, are discussed.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03876.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The incidence and symptoms of cystic bone disease in New World monkeys are described. It is suggested that the condition is of infectious origin and resembles a disease inCercopithecus aethiopswhich had been injected with material from a Burkitt's lymphoma.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03877.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1964.tb03878.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY