摘要:

InXiphophorus helleriseveral alleged instances of sex inversion in females were described. Later researchers, doubting such findings, regarded the species as having separate sexes, of males, strong and weak, and females, strong and weak, in relation to the differing ratios of male and female sex determiners, and they considered the alleged sex inverted specimens to be cases of arrhenoidy of old females or weak males, in which the male secondary sex characters appear late so that in the male immature stage they could be mistaken for young females.

ISSN:0373-4137    

DOI:10.1080/11250008009440315

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The oesophagus and the stomach ofMicrocosmus polymorphusHeller have been studied in form and function.

ISSN:0373-4137    

DOI:10.1080/11250008009440316

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Observations by previous authors on the female reproductive system of the Cladocera are specified and discussed. The position of subsequent parthenogenetic oogenesis, the appearance and arrangement of the four cells in each oocyte cluster during growth, and the yolk structure are reported. The finding indicate thatLeplodorayolk differs from that in the other Cladocera. The formation, structure and evolution of the brood chamber inBytholrephesand the structure of the oviduct inSidaandDaphniaare described.

ISSN:0373-4137    

DOI:10.1080/11250008009440317

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

In this paper I report on the morphological characteristics ofAcanthocyclops robustusSars, found in Lake Monterosi in the years 1975–77. The specimens have been compared with those collected from the same lake in 1965 and with a population ofA. robustusof a permanent pond in Castel Porziano (Latium), previously studied.

ISSN:0373-4137    

DOI:10.1080/11250008009440318

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Metaphase cytological preparations ofCuliseta longiareolata (Diptera: Culicidae) were stained with Coriphosphine-O after chemical treatments which induce C-banding. The HCl step has been shown to play a critical role in determining colour banding of preparations treated with Ba(OH)2. The results are discussed in connection with the findings from other species.

ISSN:0373-4137    

DOI:10.1080/11250008009440319

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

We investigated the applicability of Verneaux and Tuffery's Biotic Index in a study of the benthic macroinvertebrates of the River Brenta within the ambit of research into the quality of its waters.

ISSN:0373-4137    

DOI:10.1080/11250008009440320

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

ISSN:0373-4137    

DOI:10.1080/11250008009440321

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The aim of this work was to verify if starvation influences the appearance of the definitive upper jaw inOphryotrocha puerilis(Annelida, Polychaeta). On the basis of the data obtained from two series of experiments carried out parallelly on individuals ofO. puerilis, maintained in pair culture or in isolation, the following results were obtained. Starvation did not interfere with the replacement of the juvenile upper jaw by the definitive upper jaw in the animals kept in isolation; rather, the appearance of the definitive upper jaw showed a frequency significantly lower than that shown by the controls in those maintained in pair culture and under starvation for one month. The following interpretation is suggested. Starvation by itself does not influence the replacement of the juvenile upper jaw with the definitive; nevertheless, in the presence of some other environmental factor, such as pair culture (the Paarkultur of Hartmann & Huth), starvation does exert some inhibiting influence on the replacement of the upper jaw.

ISSN:0373-4137    

DOI:10.1080/11250008009440322

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

White and red axial muscle fibres of the grey mullet were studied by electron microscopy and morphometry. No significant difference was found between white and red fibers in their percentage of sarcoplasmic reticulum and T system, in location of triads and also in myofibril organization. However, red fibres were found to be richer in mitochondria and energy reserves than white fibres and this supports the view that these two fibre types play different roles in swimming locomotion.

ISSN:0373-4137    

DOI:10.1080/11250008009440323

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Karyotypes ofColitis macrotirusandTurtur chalcospiloswere analysed. Data related toColitisrepresent the first karyological analysis in a species of the order Coliiformes; comparison of theTurtur chalcospiloskaryotype with that of other Columbiformes revealed chromosomal change mechanisms of karyotype unknown within the order.

ISSN:0373-4137    

DOI:10.1080/11250008009440324

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor