DEVELOPMENT OF ELASMOBRANCH FISHES. 287 



Postscript 



It was my original intention to have given an account of 

 the development of the generative organs. In the course, 

 however, of my work a number of novel and unexpected points 

 turned up, which have considerably protracted my investiga- 

 tions, and it has appeared to me better no longer to delay 

 the appearance of this monograph, but to publish elsewhere 

 my results on the generative organs. In chapter YI. p. loO et 

 seq. the early stages of tlie generative organs are described, 

 but in contemplation of the completion of the account no 

 allusion was made to their literature, and more especially to 

 Professor Semper's important contributions. I may perhaps 

 say that I have been able to confirm the most important result 

 to which he and other anatomists have nearly simultaneously 

 arrived with respect to Vertebrates, viz. that the primitive 

 ova give rise to both the male and female generative products. 



