ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 441 



follicle. There is bo increase in number of epithelial cells. The con- 

 nective-tissue which penetrates into the follicle arises chiefly from the 

 theca interna, and to a less extent from the theca externa. Of the cells 

 arising from the former, some but not all are transformed into little fusi- 

 form cells which penetrate between the epithelial cells. The vessels of 

 the corpus luteum arise from the vessels of the theca. 



Ovarian Ova in Mammals.* — Herr J. A. Amann describes the ovary 

 of a woman of sixty-three, in which there appeared to be a formation of 

 primitive ova and structures like primary follicles. 



Prof. W. Flemming f describes the ovarian ova of the rabbit, the 

 reticular junctions of the coiled threads of the cytoplasm, the formation 

 of yolk-granules in the threads and their passage out of them as they 

 grow larger, the membrane of the germinal vesicle, and, in short, the 

 general structural features. 



Transplantation of the 0vary4— Sig. C. Foa has experimented with 

 rabbits. An adult ovary if transplanted degenerates rapidly ; the em- 

 bryonic ovary, on the other hand, may flourish and develop if trans- 

 planted to appropriate new surroundings. An embryonic ovary trans- 

 planted into an adult female develops and gains the state of sexual 

 maturity much sooner than one transplanted into a young immature 

 female. Thus it abbreviates the normal period of development. If an 

 embryonic ovary is transplanted into a female at the period of the meno- 

 pause, it is rapidly absorbed and disappears. The author refers to the 

 interest of these experiments in connection with the " autonomy of the 

 germ-plasm in respect to the somatoplasm ; " but it will surely be difficult 

 to find any one, certainly not Weismann, who believes in what this 

 phrase suggests. 



Spermatogenesis in Mammals.§ — Prof. V. von Ebner confirms his 

 previous conclusion that the spermatocytes of mammals (the rat) show 

 two divisions in rapid succession, with a short resting stage between. 

 The first division is heterotypic, the second hombotypic. In the first 

 there are in the prophases 8 annular chromosomes and in the anaphases 

 16 ; in the second the number of chromosomes increases from 8 to 16, and 

 becomes 8 in the anaphases. Neither can be interpreted as a reducing- 

 division in Weismann's sense. The author proceeds to discuss the volu- 

 metric relations of the chromatin at different stages. 



SpermatogenesisinSparrow.i] — Gustave Loisel begins with an 

 account of the prespermatogenetic period in Passer domesticus, a period 

 in which there is enormous increase of size. Spermatogonia of the first 

 order began to multiply rapidly about the end of February or the begin- 

 ning of March, and the multiplication is exclusively by direct division. 

 The history is continued from spermatogonia of the first order to those 

 of the second order, and from these to spermatocytes. Then follows the 

 period of retrogressive change or metaspermatogenesis. The spermatozoa 

 almost always degenerate in the course of a kinesis, but the previous 

 multiplication is amitotic. 



* Festschrift C. v. Kuppfer, Jena, 1899, 14 pp. and 1 pi. 



t Tom. cit., pp. 320-4 (1 pi.). See Zool. Centralbl., vii. (1900) pp. 413-4. 



j Atti R. Accad. Lincei (Rend.), ix. (1900) pp. 230-2. 



§ SB. K. Akad. Wiss. Wien, cviii. (1899) pp. 429-47 (1 pi. and 21 figs.). 



|| Journ. Anat. Physiol., xxxvi. (1900) pp. 160-85 (7 figs, and 4 pis.). * 



