720 summ:ary of cuerent researches relattng to 



SUMMAEY 



OF CrRREIfT RESEARCHES RELATING TO 



ZOOLOGY AND BOTANY 



{principally Invertebrata and Cryptogamia), 



MICROSCOPY, &c., 



INCLUDIXG OKIGIN.Ui COinrUNICATIONS FROM FELLOWS AND OTHERS* 



ZOOLOGY. 



A. GENERAL, including- Embryology and Histology 



of the Vertebrata. 



Development of the Sterlet.f — Professor W. Salensky gives a 

 resume of his Russian paper on this subject. The segmentation of 

 the e^g is on the amj^lublastula type ; the gastrula, however, is an 

 archigasfrida. In the endodermal origin and in the primitive forma- 

 tion of its mesoderm the sterlet resembles Amphioxus, but it differs 

 from it in having the chorda dorsaUs derived frum the mesoderm, and 

 not from the endoderm. There is no real difference in the meso- 

 dermal layer of these two forms, and intermediate stages between the 

 two conditions have been observed in Elasmobranchs. So, also, the 

 author thinks that the segmentation of the ovum presents a transi- 

 tional arrangement between the bony fishes and Plagiostomes on the 

 one hand, and the Cyclostomata and Amphibia on the other. 



Microscopical Phenomena of Muscular Contraction— Transverse 

 striation of the smooth fibres. J — In 1863, M.Ch. Eouget pointed out 

 that alternately bright and dark bands were often seen on the " smooth" 

 muscles of invertebrates when living, presenting great analogies to 

 true transverse strite, and that this striation was also observable in 

 certain cases in the bundles of smooth fibres of the human dartos, and 

 in those of the gizzard of fowls. In the present communication he 

 describes the results of experiments which he undertook to determine 

 the conditions under which this striation of the smooth fibres takes 

 place, and the mechanism of its production, and considers that be has 



* The Society are not to be considered as responsible for tlie views of the 

 authors of the papers referred to, nor for the manner in which those views 

 may be expressed, the main object of this part of tlie Journal beinoj to present a 

 summary of the papers as actually publiahed, so as to ]>rnvide the Fellows with 

 a guide to the additions made from time to time to the Library. Objections and 

 corrections should therefore, for the njost part, be addressed to the authors. 

 (The Society are not intended to be denoted by the editorial " we.") 



t Arch, de Biol., ii. (1881) pp. 233-78 (4 pk). 



X Comptes Eendus, xcii. (1881) pp. 1446-9. 



