154 T. H. Morgan. 



centage of eggs that segmented. The following four records 

 were obtained in this way: For August ii — 33, 10, 100, 95, 95, 

 75, 10 per cent. For August 16 — 30, 30, 10, i, 75, 90, 85 per 

 cent. For August 19 — 33, o, 10, 4, 4, o. For August 20 — 12, 4. 

 A much larger number of individuals gave off neither eggs 

 nor sperm, and some produced sperm and no eggs, and vice versa. 

 The results in the above list show all conditions from perfect 

 self-fertility to absolute self-sterility, although some of the latter 

 cases may have been due to no sperm being given off. 



A few preliminary trials were made with two (A and B), and 

 with three (A, B, and C) individuals. The scheme of crossing 

 is given in the following diagrams: 

 For Two Individuals. For Three Individuals. 



Comparing the self-fertilized eggs with the crossed-eggs. It 

 Is clear that while self-fertilization did not take place in nine 

 cases, and In only one egg in the other case, yet cross-fertilization 

 more frequently occurred, but never so completely as when many 

 individuals normally deposited their eggs and sperm together. 

 In addition to these cases there were three others in which none 

 of the eggs, neither self- nor cross-fertilized, segmented. One 

 of the results with three individuals is given In the next table : 



A^ B*^ 2 C^ 



B^ few A'' very few B"^ 25 



75 Orare A^ 4 



