96 THE CHANGES PROM STAGE A TO P. 



in the case of the anterior somites, and, indeed, may be 

 described as being common with that of the opposite side. 

 However this may be, the two openings soon become definitely 

 united to form a single opening, — the generative opening, while 

 the tubes themselves persist as the generative ducts. Whether 

 any large portion of the latter are ectodermal in origin, that is 

 to say, derived from a growth of the lips of the opening at 

 its first appearance, it is impossible to say. Kennel asserts 

 that a large part of the generative duct is so derived, but 

 it is obvious that such a statement, as in the case of the 

 anterior segmental organs, cannot be regarded as anything 

 more than an expression of probability. It is impossible 

 to settle the question by sections, and I know of no other 

 method. 



From the above description of the origin of the generative 

 organs and their ducts, which is in the essential points identical 

 with that of my tentative preliminary account (No. 50), it is 

 obvious that Kennel has failed to trace the origin of the 

 germinal nuclei. He also differs from me as to the origin of 

 the generative tubes themselves, which, he asserts, come from 

 the dorsal divisions, not of a series of somites, but of one 

 single pair. If his account is correct, which, seeing that he 

 has not observed the origin of the germinal nuclei, I am 

 inclined to doubt, it would appear that the generative tubes of 

 the Cape species diflfer from those of the West Indian in this 

 respect. He adopts my account of the derivation of the gene- 

 rative ducts and their openings from the lateral divisions of a 

 pair of somites, though, curiously enough, in another place he 

 stigmatises my description as " falsch." 



It thus appears that in Peripatus capensis the nephridial 

 portion of the twenty-first somite does not separate from the 

 median or generative portion, but remains in connection with 

 the latter and forms the channel by which the generative part 

 of the ccelom communicates with the exterior. The generative 

 ducts are therefore modified nephridia, but it is important to 

 notice that the connection between them and the generative 

 tubes is not to be compared with the so-called funnel of the 



