ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 35 



hatching, and the author was not able to find any vascular system 

 either in the embryo or vitellus up to fourteen or fifteen days after 

 development begins, that is four or five days after hatching. In 

 this respect the observations of Ryder, Kingsley, and Conn agree 

 with his, although in non-pelagic teleostean eggs an elaborate circu- 

 latory system is developed both in the vitellus and in the embryo a 

 considerable time before hatching. 



Mr. Brook has nothing new to record in the later stages of 

 development. 



Vesiculse seminales of Guinea-pigs.* — The contents of these 

 organs are a secretion composed of microscopic spheres of a slimy 

 consistency. Spermatozoa occur only in small quantities, and are 

 not to be considered, according to C. S. Minot, as being normally 

 stored in these organs. The proper secretion is probably formed 

 within the vesiculfe by its lining epithelium of granular cylindric 

 cells with oval nuclei basally disposed. This epithelial membrane 

 is raised into numerous folds, composed of the two approximated 

 layers separated merely by a thin connective tissue. !N"o parallel 

 is found for this arrangement in Mammalia, but Minot compares 

 Coelenterata and the gastric diverticula of crickets. 



There is no similarity between the contents of the vesiculae 

 seminales of guinea-pigs and the fluid of the human prostate. Hence 

 there is no ground for identifying the two secretions as having a 

 common origin, or for assuming that the vesiculae of the guinea-pig 

 serve merely as reservoirs to store up the secretion of the prostate. 



Histology of Hairs, Setae, Spines, and Feathers.j — W. Lwoff 

 gives an account of his work which has already appeared in extenso 

 in Russian. The chief constituent of hairs and feathers is the so- 

 called cortical substance, from which, after treatment with caustic 

 potash and teasing, spindle-shaped cells with fine filamentar nuclei 

 may be obtained. Some of the cells break up into extraordinarily 

 fine filaments. The cells are held together by an intermediate 

 substance. The spines of the hedgehog likewise break up into fine 

 fibrils which have the appearance of those of connective tissue, but 

 do not, however, swell up or undergo any change under the influence 

 of acetic acid ; they appear rather to consist of a horny substance. 



In order to study the process of the formation of the fibrils in the 

 cell-substance, the author investigated the structure of young feathers ; 

 after two or three days' maceration in weak acetic acid the cells were 

 easily isolated ; they were found to be rounded or cubical, to be 

 arranged in long rows, to be faintly coloured, and to contain a large 

 nucleus, with nucleoli ; the surface of connection between the cells is 

 uneven, and is provided with extremely fine processes, like denticles. 

 These cells elongate and become more or less long cylinders, while 

 their nuclei likewise elongate, and become oval in form ; at the same 

 time the boundaries between the cells become indistinct. The median 

 part of the cell becomes convex and passes into prolongations, by 



* Arch. f. Mikr. Anat., xxiv. (1884) pp. 211-6 (1 pi.), 

 t Bull. Soc. Imp. Nat. Moscou, 1884, pp. 141-74 (4 pis.). 



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