136 T. H. Morgan. 



the spermatozoa of an Individual will not fertilize the eggs of 

 that individual, but have the power to fertilize the eggs of any 

 other individual. 



My object in undertaking a study of this problem was, in the 

 first place, to determine if possible the nature of the conditions 

 that prevent or interfere with self-fertilization; and in the second 

 place, I was not without hope of being able to find some way 

 in which self-fertilization could be artificially Induced. As will 

 appear in the sequel, these two questions are not two sides of 

 the same problem ; for, while it has been possible to discover the 

 means of bringing about self-fertilization, it still remains to be 

 definitely determined what conditions In the egg normally prevent 

 the entrance of the spermatozoa of the same Individual. 



Since Castle's observations had shown that the ascidlans offer 

 favorable material for a study of this sort, I first turned my 

 attention to this group, using the three most available species 

 found at Woods Hole, or in the vicinity; namely, Ciona intes- 

 tinalis, Molgula manhattensis, and Cynthia partita {Styela sp.). 

 The work was done while holding the Bryn Mawr Table at the 

 Marine Biological Laboratory, from June to September, 1903. 

 Owing to the scarcity of Ciona I have not been able to work out 

 completely a number of Important problems connected with one 

 of the two main questions that I examined. In the near future 

 I shall hope to complete this side of the investigation. 



EXPERIMENTS WITH CIONA INTESTINALIS. 



The ovary of Ciona Is a sac-shaped body of fair size lying 

 loosely attached in the coil of the Intestine. It can easily be 

 removed without cutting Into the testis. Its lumen contains some 

 of the ripe eggs, but the majority of these are in the oviduct. 

 The oviduct can readily be opened and the eggs set free without 

 cutting into the vas deferens, which follows a course parallel to 

 the oviduct. If the animal is kept Isolated for 24 hours the ovi- 

 duct becomes greatly distended with eggs, and after another 24 

 hours even more eggs may have accumulated. The eggs are 

 laid normally In the early morning, at dawn, and Castle has re- 

 corded that Ciona deposits its eggs and sperm with the regularity 



