黄鼬雄性生殖腺的发育及组织结构

本试验应用组织学技术,对四例不同时期野生成体雄性黄鼬的生殖腺进行观测.结果表明,生殖腺在11月份处于静止期,自12月份开始发育,翌年1月份生精细胞及间质细胞结构变化显著,至同月中旬在附睾尾部出现精子,即生殖腺已具成熟.该结果较一般资料所述的雄鼬发情时间有所提前.     

白鼬和黄鼬直针毛的扫描电镜分析

应用扫描电镜对白鼬(Mustela erminea)和黄鼬(M.sibirica)背部和腹部直针毛的鳞片花纹类型进行了研究。结果表明,白鼬和黄鼬同一部位直针毛鳞片花纹的排列顺序、主要鳞片类型、鳞片高度、密度以及同种类型鳞片的外部形态均存在一定差异,即种间均存在差异,而在种内则表现出较高的相似性和一致性。白鼬背毛和腹毛主要鳞片类型均为长瓣型,杂波型次之;黄鼬背毛和腹毛的主要鳞片类型均为杂波型,长瓣型次之。背毛和腹毛杂波型鳞片的密度在2种动物间差异均极显著(p<0.01),背毛长瓣型鳞片的密度和高度在2种动物间差异均显著(p<0.05)。据此,笔者分析了利用鼬科动物毛鳞片花纹进行物种鉴定的可行性及需要注意的问题。     

Two remarkable nematodes from sharks in Japan

Two species of nematodes, Acanthocheilus rotundatus (Rudolphi, 1819) and Metaleptus rabuka Machida, Ogawa and Okiyama, 1982, have been recorded from the stomach of Mustelus griseus Pietschmann and M. manazo Bleeker (Triakinidae, Carcharhiniformes) and from the intestine of Apristurus fedorovi Dolganov (Scyliorhinidae, Carcharhiniformes), respectively, from the North Pacific Ocean off Honshu, Japan. Both species are redescribed and their cephalic structures have been studied, for the first time, by scanning electron microscopy. A. fedorovi represents a new host record for M. rabuka. The morphology of M. rabuka, particularly the presence of a somewhat trilobed pseudolabia, an undivided oesophagus and the structure of the male caudal end, shows that it is necessary to transfer the monotypic genus Metaleptus Machida, Ogawa and Okiyama, 1982 from the Physalopteroidea to the Gnathostomatoidea, where a new subfamily, Metaleptidae subfam. n., is established to accommodate it. Undoubtedly, Metaleptus represents a very old and primitive form of nematode, the morphology of which indicates affinities also to physalopterids, cucullanids and acanthocheilids.     

Protective chemicals in caterpillar survival

Summary Using two species of caterpillars; larvae of the swallowtail butterfly, which produce large amounts of iso-butyric and 2-methylbutyric acids, and larvae of the puss moth, which produce no such detectable volatile compounds, it was shown that the insect which utilizes a chemical defense is better protected from its natural enemy, a praying mantis.