014 DR GREGG WILSON ON 



backward growth of the foundation. He had apparently expected to find some such 

 origin of the Miillerian ducts as Semper had described in the Elasmobranchs ; for he 

 says his results, though so simple, had cost him much trouble, inasmuch as he had 

 expected them to be quite different. He also mentions that he carefully examined the 

 tip of the foundation to determine if it showed any communication with the peritoneal 

 epithelium such as WALDEYEE had previously found in the chick ; but he saw no evidence 

 of this. The peritoneal epithelium and the growing duct appeared sharply marked off 

 from one another, except in some specimens that had been cut obliquely, or that had 

 suffered otherwise in the course of preparation. 



Mihalkovics confirmed the observations of Braun. He examined the adder and 

 lizard, and found that at the proximal end of the Wolffian body, and lateral to it, the 

 coelomic epithelium becomes cylindric over a triangular area. The edges of the distal 

 end of this area rise till they meet, and form a closed tube or funnel. This runs to a 

 fine point, which grows back in a previously formed Tubenfalte. Mihalkovics com- 

 pared the early foundation to a slipper set on end : the elongated oval opening repre- 

 senting the mouth, while the closed part of the shoe corresponds to the part of the duct 

 formed by the union of the lateral edges of the foundation. Mihalkovics denied that 

 the development of the Miillerian ducts of reptiles was at all dependent on the meso- 

 nephric duct. He believed that growth backwards was effected by increase of the cells 

 at the tip of the foundation. 



Hoffmann's general concurrence in the views of Braun and Mihalkovics is the 

 more remarkable because of his published work on the ducts of Rana and Triton, in 

 both of which he described at least partial derivation of the Miillerian ducts from the 

 segmental ducts. In the lizards he mentions a relatively high cylinder-epithelium, lying 

 ventral to the coelom in the region of the pronephros. Further on he describes the 

 epithelium ventral to the pronephros, as distinguished from that of the lateral and median 

 parts by the high form of its cells ; and he adds that it is this patch of epithelium that 

 forms the foundation of the Miillerian duct. The heightened epithelium passes laterally 

 till it comes into close proximity to the segmental duct, and can be followed back along 

 this duct to the cloaca — at least, in female specimens. It is by invagination of the high 

 cylindric epithelium of the pronephros that the ostium abdominale of the Miillerian duct 

 is formed. Hoffmann concludes that in the case of the lizards further development is 

 independent of the segmental duct ; but, at the same time, he says he is unable to deter- 

 mine whether the growth backwards of the Miillerian duct is also independent of the 

 thickened band of epithelium that lies immediately external to it. 



Wiedersheim investigated the development of the Miillerian ducts in Crocodilus and 

 Chelone. He agrees, in the main, with previous workers on the reptiles, but finds that in 

 Chelone the backward growth of the Miillerian duct foundation is dependent on prolifera- 

 tion of the cells of the thickened epithelium outside the duct. 



