736 



Nachdruck verboten. 



The Development of the Müllerian Ducts in Axolotl. 



By Geegg Wilson, M. A., B. Sc, Edin. 



(Aus dem Anatomischen Institut zu Freiburg i. Br.) 



With 22 Figures. 



Although the development of the Müllerian duct of Amphibians 

 has been the subject of but little special study, there are already 

 several contradictory accounts of its progress. Leydig and Wittich 

 believed in a transverse division of the segmental duct, 

 so that the anterior part might give rise to the Müllerian duct, 

 while the posterior continued to function as a ureter ; Spengel, work- 

 ing in Semper's Institute at Würzburg, said that the Müllerian 

 and Wolffian ducts were formed by a progressive longitu- 

 dinal splitting of the segmental duct from before backwards, and 

 his view has been adopted by Fürbringer and Hopfmann ; Kollmann 

 admitted the fact of a longitudinal splitting, but conceived that, alike 

 in Selachians and Amphibians, the whole of the anterior part of the 

 segmental duct was converted into the ostium abdominale of 

 the Müllerian duct, and emphasized his opinion that the segmental 

 duct itself, and consequently the derivative Müllerian duct, arose 

 from the coelomic epithelium; Schneider nearly twenty years ago 

 maintained that the Müllerian duct originated in Rana indepen- 

 dently of the segmental duct, and quite recently Mac Bride 

 has come to the same conclusion, while Semon and Jungersen work- 

 ing on other Amphibians have published similar results. 



I hope soon to be able to give a full account of the observations 

 on Amphibian larvae that have led me to regard the mode of origin 

 described by Schneider, Mac Bride, Semon and Jungersen as the 

 actual one. In the meantime I shall describe the facts that I have 

 observed in Axolotl (Siredon pisciformis), a type that has not hitherto 

 been investigated in this connection, so far as I know. 



The smallest Axolotl that I have had was 25 mm in length. It 

 shows a well-developed pronephros with both the nephrostomes open, 

 and with no signs of degeneration; and on, and posterior to, this 

 pronephros there is a well-defined epithelial Anlage, that later 

 stages prove to be the first foundation of the Müllerian duct. It 

 is noteworthy, on the one hand, that the Müllerian duct is compara- 

 tively late in being laid down ; the segmental duct, from which it has 



