Self -Fertilization Induced by Artificial Means. 155 



In this experiment the a- and c-sperm did not self-fertilize, but 

 the former did well with C- and the latter with B-eggs. The 

 b-sperm self-fertilized to a slight extent, but did no better with 

 the A- and with the C-eggs. 



In the next series the results are more striking: 



A^ 

 B^95 

 O50 



Here none of the sperm self-fertilized the eggs. The a-sperm 

 did quite well with the B- and C-eggs (95 and 50 per cent) . The 

 b-sperm did well with the A-eggs, but not with the C-eggs. The 

 c-sperm did well with the A-eggs, but not with the B-eggs. It 

 may appear from the preceding table that there is something more 

 involved than simply the question of good sperm, for the same 

 sperm appears to act differently with different eggs. 



Another experiment with three individuals gave no eggs self- 

 fertilized, but good cross-fertilizations with the c-sperm; less good 

 with the b-sperm. These experiments should be carried out on 

 a larger scale, and at different times of the year, but they suffice 

 to show that self-fertilization is very infrequent when the process 

 is an artificial one. It takes place to a considerable extent in some 

 cases when eggs are normally laid. Moreover the artificially 

 crossed eggs do not segment nearly so well in Cynthia as in Ciona. 



The next experiment shows the action of ether on self- and 

 cross-fertilized eggs. Some of the eggs and sperm of one in- 

 dividual, A, were removed and put into sea-water. Other eggs, 

 A% were self-fertilized in an ether-solution, and a third lot, A^, 

 were crossed with sperm from B (A-sperm was also present). 

 The same process was carried out with B which was crossed with 

 sperm from A. 



A BO 



A^' few B'' few 



A'' very few B^ very few 



The results show that the self-fertilized eggs in ether did as 

 well as those that were crossed, but none of the eggs in water alone, 



