i io THE PHYSIOLOGY OF REPRODUCTION 



energy, for it is incapable of active movement. The metabolic pro- 

 cesses of the ovum, therefore, are almost entirely constructive, while 

 those of the spermatozoon are largely destructive. The function of 

 the ovum is to conjugate with the spermatozoon, and subsequently, 

 by a lengthy process of cell division, to give rise to a new individual. 



FIG. 24. Section through ovary of adult dog. (From Waldeyer.) 



a, Germinal epithelium ; fc, remains of egg-tubes ; c, small follicles ; d, more 

 advanced follicle ; e, discus proligerus and ovum ; f, second ovum (a rare 

 occurrence) ; g, theca externa of follicle ; /*, theca interna ; t, membrana 

 granulosa ; Ic, degenerate follicle ; /, blood-vessels ; m, tubes of paro- 

 varium ; ^, involuted germinal epithelium ; z, transition from germinal 

 to peritoneal epithelium. 



The mammalian ovary, 1 or organ in which the ova are produced, 

 is composed of a stroma of fibrous connective tissue, which contains 

 some plain muscular fibres (especially in the neighbourhood of the 



1 See also Stratz, Der gcachlecktsreife Sdiigethiereierstock, Haag, 1898. 



