OF THE MULLERIAN DUCT OF AMPHIBIANS. 511 



Amphibien." he adds the note : " Anhangsweise sei noch bemerkt, dass sich mir an Triton- 

 larven ergeben hat, dass auch bei Amphibien die Bildung des Wolff'schen und Miiller'- 

 schen Ganges durch eine von vorn nach hinten fortschreitende Spaltung des primaren 

 Urnierenganges erfolgt, wie es Semper fiir die Haie nachgewiesen hat." But, so far as I 

 have been able to ascertain, Spengel never published any details to support this part of 

 his preliminary notice : his later paper, " Das Urogenital-system der Amphibien " (1876), 

 embraces only the anatomical part of his researches. Semper, however, gives him as his 

 authority for the statement that in female Amphibia, the splitting of the segmental 

 duct is complete, while in the males it is incomplete ; but, perhaps, this is a mere 

 anatomical observation. And Spengel himself, writing on the Ccecilia, says : " Nach 

 den von mir von andern Amphibien vorliegenden Beobachtungen entsteht der Harnleiter 

 in dieser Thierclasse wie bei den Selachiern durch eine von vorn nach hinten fortschrei- 

 tende Abspaltung an der medialen Seite von dem einfachen Urnierengang." 



In 1876 a paper by A. Schneider appeared, representing a totally different view. 

 The error of Wittich and Leydig, in supposing that the anterior of the segmental duct 

 was simply converted into the Mtillerian duct, was shown by the fact that the two ducts 

 run side by side for a considerable period of the larval life of Urodeles. In the case of 

 the frog, the appearance of young cells " um den Wolff'schen Gang " is described : 

 "Wahrend nun die vordere Strecke des Wolff'schen Ganges schwindet, entsteht aus den 

 jungen Zellen der Miiller'sche Gang." This work, like Spengel's, was a short one, and 

 without illustrations, but it is interesting as anticipating the conclusions of Jungersen 

 and MacBride. 



In 1877 Furbringer's splendid account of the " Entwickelung der Amphibienniere " 

 appeared. He adheres to the conclusions of Spengel ; but as he gives the process of 

 reasoning by which he was led to do so, it is possible to combat the inference, and I 

 shall, later on, offer another explanation of his facts. # In subsequent writings he renewed 

 his statements as to the splitting of the segmental duct. 



The next work of importance was Hoffman's " Entwickelungsgeschichte der 

 Urogenitalorgane bei den Anamnia" (1886). Kollmann had in 1882 written on 

 ;( Verbindungen zwischen Ccelom und Nephridium," but as his paper rather aims at 

 giving an explanation of the work of others than stating new facts, it can hardly be 

 used as evidence for either side of the controversy, though it might be claimed for both. 

 Kollmann accepts the view that the Mtillerian duct arises from the segmental duct, 

 but insists that it is ultimately a derivative of the ccelomic epithelium. 



Hoffmann's very elaborate descriptions of the Mtillerian duct in the frog and newt 

 are the most exhaustive that we have, — at least, with the exception of Jungersen's. 

 He, too, adopts the view that there is a splitting of the segmental duct; but he makes 

 an important modification as to the frog : he says, " Nur ein kleines Stuck des Miiller'- 

 schen Ganges entsteht durch Abspaltung von dem urspriinglichen Segmentalgang, der 

 iibrige bei Weitem grosser e Theil, d.i., das ganze Ostium abdominale tubse so wie der 



* See pp. 517-518. 



