( -^02 ) 



My opinion is that these investigations siiow tliat tlie vasa efferentia 

 testis must not be considered as simple tubules of tlie mesonephros, 

 but newly formed tubules, which use quite or for the greater part 

 the way given to them by the tubules of tlie mesonephros. And that 

 they are able to use this way finds its cause in this, that, according 

 to Felix and BtJHLER^) there is most probably no idea of a functioning 

 of the mesonephros in monodelphic mammals, even not in the pig, 

 where it is so strongly developed. 



Not so in the didelphic mammals. Here the mesonephros does 

 not only function embryonally, as is known, but still during the 

 first period of the individual life. A separation of the mesonephros 

 in two parts as is found in reptilia does not come about here. 



The connection of the genital gland, especially of the testicle and 

 its duct, the Wolffiian duct, could not, it may be supposed, in the 

 stadium in which this connection will come about in other animals, 

 be established in marsupials with the help of tubules of the mesone- 

 phros, because these had still to fulfill their excretory function. 



Instead of this the connection could be established in such a way 

 that the Wolffian duct grews out ci'anially and brings about itself 

 the connection between the gland and its excretory duct. 



At last the tubes, whicli occur secondary and independently oi 

 the tubules of the mesonephros in the tissue of the epididymis, might 

 be explained in the same way, i.e. as tnbules which have the same 

 signification as the coni vasculosi, but foi' the same reason do not 

 originate on the bottom of tubules of the mesonephros but are 

 separated from them both locally and temporarily. 



Another view may be, that the tube which encroached in the 

 genital gland, might not be the Wolffian duct but the most cranial 

 tubule of the mesonephros so that in other words the so-called sexual 

 part of the mesonephros in marsupials should be reduced. I do not 

 believe that this conception is true, firstly because no separation 

 between the tubules can be observed, and secondly because at the 

 reduction of the mesonephros, as is mentioned abo\'e, in marsu- 

 pials, nothing can be observed, as far as my preparations are con- 

 cerned, of differences between the tubules of the mesonephros, what 

 must surel}'' be the case a( a transformation of a lubule of the 

 mesonephros to a connecting duct. 



1) Felix und Bühler, Die Entwickelung der Hani und Ciesclilechlsorgane in 

 Hertwig's Handbucli dcr vergleiclienden und experimentellen Ent wiek elungsgescbichte 

 der Wirbeltiere. 



