300 SUMMARY OF CURRENT RESEARCflES RELATING TO 



cells arise from all the connective elements of the stroma of the ovary. 

 Later on they arise chiefly from the cells of the internal theca of the 

 atrcsic follicles. They form first the false corpora lutea as a transition 

 stage. In the adult there is also a transformation of cells of the inter- 



vv;^.- 



A group of interstitial cells in the ovary of an adult Serotinus, showing 

 alveolar cytoplasm and numerous mitochondria. 



follicnlar stroma into interstitial cells. The interstitial cells in the bat 

 do not seem to have to do with rut and ovulation, but probably with 

 the nutrition of the genital system and with the determination of the 

 secondary sex characters. J. A. T. 



Parthenogenetic Development and what it Suggests. — M. Her- 

 LANT (Arch. ZooL Exper., 191:), 58, 291-:-514). (1) The simple activa- 

 tion of the ovum of Faracentrotus lividns by means of butyric acid 

 is characterized by the formation of a monaster which repeats itself 

 rhythmically without ever provoking segmentation. Only after numerous 

 attempts at division does the ovum begin to suffer self-destruction by 

 cytolysis. But this is merely tlie final result of cytological conditions 

 incompatible with life ; it is not their cause. (2) Following Loeb's 

 method, Herlant subjected the ova, activated by butyric acid, tO' 

 hypertonic solution. A new reaction is artificially induced which gives 

 the monaster the bipolarity which it lacks. This makes segmentation 

 and development possible. (3) No structure in the cell is indispensable 

 to division of the cell as a whole or of parts of the cell. The division 

 of the cell is the sum of a series of particulate and independent divisions. 

 Thus the division of the chromosomes is not the consequence of the 

 division of the centrosome. There is a general physico-chemical change 

 in the economy of the cell. J. A. T. 



Spermatogenesis of Horse.— K. Masui (Jouni. CoU. Agric. Imp. 

 Univ. Tokyo, 191!), 3, ;}.")7-76, 3 pis.). The resting nucleus of the 

 spermatogonium contains a large nucleolus and several small chromatin 

 masses. In the metaphase of ^the spormatogouia the numerous chromo- 

 somes are divided at the same time. Many symmetrical pairs were- 



