NOTES ON THE OCCURRENCE OF MALES IN POPULATIONS OF POTAMOPYRGUS JENKINSI

Freshwater prosobranch snails of the genus Potamopyrgus arerenowned for being extremely variable and for reproducing parthenogenetically;in addition they are among the very few animals which appearto have successfully colonized Europe from the Antipodes (seeFretter & Graham, 1978, and Winterbourn, 1972 for reviewsand references). During investigations into the genetics and sex ratios of P.antipodum (or antipodarum) (Gray) in New Zealand, a period ofleave allowed some comparisons to be made with the AustralianP. nigra (Quoy & Gaimard), which is the subject of a separatenote (Wallace, 1978) and the European P. jenkinsi(Smith) discussedhere. (Received 10 March 1978;     

LABORATORY OBSERVATIONS ON THE EARLY LIFE STAGES OF THE DIAMOND SQUID THYSANOTEUTHIS RHOMBUS

The early life stages of the diamond squid Thysanoteuthis rhombusfrom early embryogenesis to post-hatching (0–7 days old)were observed through laboratory incubation using egg massescollected in the southern Sea of Japan. The egg diameter andmantle length increased during embryonic development throughhatching. Mantle-length growth was linear over time, and thegrowth rate was significantly higher at 25°C than at 20°C.The inner yolk was located on the dorsal side of the mantlecavity and increased in volume through hatching. Immediatelyafter they hatched, the hatchlings remained on the bottom ofculture plates with their ventral sides facing up, but 2–3days after hatching they began to swim with their dorsal sidesfacing up. Feeding experiments were conducted, but none of thehatchlings fed. Statolith growth increments were shown to formdaily. Ontogenetic changes that occur from fertilization throughpost-hatching are discussed. (Received 8 June 2005; accepted 2 November 2005)     

头足类早期生长阶段的比较研究

本文首次系统描述了乌贼科、枪乌贼科、微鳍乌贼科和蛸科(章鱼科)浅海性种类早期生长阶段的形态特征,并与成体的形态特征相比较。对比了浅海性头足类与大洋性头足类的早期生长阶段。发现浅海性头足类在早期生长阶段中的形态变化较小,而大洋性的头足类在早期生长阶段中的形态变化较大。表明在系统演化中,浅海性头足类已走在大洋性头足类的前面。     

棘胸蛙早期胚胎发育的初步观察

在２５．１５±０．２２℃恒温条件下观察了棘胸蛙的正常胚胎发育。根据外部形态特征、主要生理特征及胚胎行为的出现,将棘胸蛙的胚胎发育划分为２７期,从受精卵到孵化出膜约２３４ｈ．胚胎发育期间的总积温（总热量）为５８８７℃。卵的受精期１．５ｈ。卵裂期历时２９ｈ３３ｍｉｎ,原肠形成期历时１６ｈ４２ｍｉｎ,器官形成期共历时１８６ｈ８６ｍｉｎ。     

ORGANIC CARBON, ENVIRONMENTAL FACTORS AND GROWTH IN THE SMALL EURYHALINE GASTROPOD, POTAMOPYRGUS JENKINSI (SMITH)

A method of analysing small invertebrates for organic carbon(in the range 6.0 to 1000 µg) is described. The relationshipsbetween organic carbon content, total dry weight and shell lengthwere detemined for Potamopyrgus jenkinsi living in differentcombinations of salinity and temperature. Differences in organiccarbon content were found in relation to weight at differentgrowth temperatures. This work is a further confirmation ofthe usefulness of organic carbon content as a measure of thegrowth or biomass of small invertebrates. ^*Present Address: School of Biology, University College, P.M.B.5323, Port Harcourt, Nigeria. (Received 27 April 1977;     

鲥鱼仔幼鱼食性与生长的初步研究

本文主要描述鲥鱼仔幼鱼阶段有关摄食、消化器官的发育、不同大小仔幼鱼食物组成特点、摄食量及其昼夜摄食节律。此外,还就仔幼鲥鱼人工饲养条件与天然状况下的生长作了比较。结果表明,只要供饵正常,孵化环道内生活的仔幼鲥生长速度可以略快于鄱阳湖同期天然生长个体的速度,为今后人工培育仔幼鲥进行放流和增殖提供资料。       

THE IMMATURE AND ADULT STAGES OF CALLOCOCCUS LEPTOSPERMI (MASKELL) (HOMOPTERA: COCCOIDEA: ASTEROLECANIIDAE), WITH OBSERVATIONS ON LIFE HISTORY

Abstract
The gall-forming scale insect Callococcus leptospermi was studied in the field to determine its life history and method of distribution on the host plant, Leptospermum sp., previously L. juniperinum (Sm.) Domin (prickly tea tree, Myrtaceae). This paper complements earlier taxonomic studies on C. leptospermi. Until now the adult female has provided most of the available data on the species. Newly described stages include the second instar male, the third instar assumed female and the adult male. The sexually dimorphic first instar and adult female are redescribed. Callococcus leptospermi is ovoviviparous. It is dispersed by migration of second instar larvae from the parent gall to new feeding sites.     

MICROTUBULES AND EARLY STAGES OF CELL-PLATE FORMATION IN THE ENDOSPERM OF HAEMANTHUS KATHERINAE BAKER

A fine structure study of the phragmoplast and developing cell plate has been made on glutaraldehyde-osmium tetroxide-fixed, dividing, cultured cells of the liquid endosperm of Haemanthus katherinae Baker. The phragmoplast arises between the telophase nuclei, usually in association with a remnant strand of spindle elements, and consists of an accumulation of microtubules oriented at right angles to the plane of the future cell plate. The microtubules, which are 200–240 A in diameter, occur in small clusters spaced at approximately 0.2–0.3 µ intervals along the plate. Short interconnections interpreted as "cross-bridges" have been observed between individual microtubules. Within each cluster there is an electron-opaque zone about 0.3 µ in width which can be attributed in part to an overlap of microtubules from both sides of the plate and in part to a local accumulation of an amorphous electron-opaque material. During development these dense zones become aligned in a plane which itself defines the plane of the plate. Vesicles, commonly observed in long files, are derived from a cytoplasmic matrix rich in elements of the endoplasmic reticulum and sparse in dictyosomes. They aggregate between the clusters of microtubules and eventually coalesce to form the cell plate.     

CYTOLOGICAL AND CYTOCHEMICAL OBSERVATIONS ON THE EARLY STAGE OF INFECTION OF TOMATO HAIR CELLS BY TOBACCO MOSAIC VIRUS

Strips of epidermal tissue bearing hair cells were removed fromtomato stems. The lower surface exposed by the stripping wasinoculated with tobacco mosaic virus and the progress of infectionof the hair cells was followed microscopically and by extractionof infectivity. Shortly before infectivity could be extractedfrom the hair cells, the nuclei were observed to have migratedtowards the tran sverse wall of the basal hair cell nearestthe epidermis, apparently the site at which infection of thecell commences. After infection was apparent, the staining characteristicsof the nuclei, before and after RNase and DNase treatment, suggestedan accumulation of RNA. A granular body, different from X-bodiesmaintained a close association with the nucleus of TMV infectedhair cells, and was found to be rich in RNA, suggesting thatviral RNA of the nucleus may have been entering the cytoplasmvia the granular body. A possible mechanism of X-body formationarising from the granular body is suggested. ¹ Supported in part by a grant E-536 (C9) from the U. S. PublicHealth Service. ² Present address: Plant Pathology Laboratory, Faculty of Agriculture,Nagoya University, Anjo, Aichi (Japan). (Received March 4, 1963; )     

金黄仓鼠早卵裂期胚胎发育的研究

研究结果证明:(1)本研究制备和采用的金黄仓鼠(Mesocricetus aurilus)血清是体外培养金黄仓鼠胚胎的有效成分;(2)丙酮酸钠和乳酸钠加入TC-199液中可显著提高金黄仓鼠胚胎的发育率;(3)TC-199(Ⅱ)、台氏液和杜氏液加适量FCS或PHS都是培养金黄仓鼠胚胎的有效培养液;(4)本研究中已观察到4-细胞期胚胎在体外培养时的进一步发育;(5)金黄仓鼠2-细胞期胚胎移植至雌金黄仓鼠受体的输卵管中可继续发育,培养子兔输卵管中可存活44小时以上。