VI.] THE TESTES. 167 



Pfliiger (Die Eierstocke der Sdugethiere u. des Menschen, Leipzig, 1863) de- 

 scribed the ova as arising, in mammals, out of the epithelium of tubular glands, 

 a chain of several ova being frequently found in one tube and the tube be- 

 coming subsequently divided by constrictions into as many follicles. According 

 to Waldeyer however, whose account we have followed above, the primordial 

 ova make their appearance as individual specialized epithelium-cells, without the 

 preformation of any tubular glands, the capsule or Graffian follicle being a later 

 product. Waldeyer's views have been on the whole generally accepted (Leo- 

 pold, Untersuch. iiber das Epithel. des Ovariums. Inaug. Diss. Leipzig. 1870, 

 Eomiti, Max Schultze's Archiv, 1873, Bd. x.), though opposed by Kapff (Rei- 

 chert and Dm Bois Reymond's Archiv, 1872), and more recently by SernofF 

 (loc. cit.). 



The first traces of the testes are found in the dorsal and 

 inner side of the intermediate cell-mass, and appear about the 

 sixth day. From the first they differ from the rudimentary 

 ovaries, by coming into somewhat close connection with 

 the Wolffian bodies ; but occupy about the same limits from 

 before backwards. The mesoblast in the position we have 

 mentioned begins to become somewhat modified, and by the 

 eighth day is divided by septa of connective tissue into a 

 number of groups of ceils ; which are the commencing tubuli 

 seminiferi. By the sixteenth day the cells of the tubuli have 

 become larger and acquired a distinctly epithelial character. 



Waldeyer is of opinion that the tubules of the Wolffian body penetrate into 

 the tissue from which the testes are formed, and becoming much finer than the 

 remainder of the tubules constitute the 'tubuli seminiferi.' Apart from its 

 inherent difficulties, this view has not been corroborated by any subsequent 

 observer. 



It is distinctly denied by SernofF (loc. cit.), who further states that the testes 

 are entirely formed out of the mesoblast of the intermediate cell-mass, and that 

 their rudiments have no connection either with the germinal epithelium or with 

 the tubules of the Wolffian body. 



We have now described the origin of all the parts which 

 form the urinary and sexual systems, both of the embryo and 

 adult. It merely remains to speak briefly of the changes, 

 which on the attainment of the adult condition take place in 

 the parts described. 



The Wolffian body, according to Waldeyer, may be said 

 to consist of a sexual and urinary part, which can, he states, 

 be easily distinguished in the just-hatched chick. The sexual 

 part becomes in the cock the after-testes or coni vasculosi, 

 and consists of tubules wdiich lose themselves on the one 

 hand in the seminiferous tubules, and on the other hand, in 

 birds, probably form the whole of what can be called the 

 epididymis. In the hen it forms part of the parovarium of 



