Self-Fertilization Induced by Artificial Means. 139 



the postulated effect, or if the presence of the extract of the ovary 

 of another individual has the postulated effect on the sperm, fer- 

 tilization ought to have occurred. The results showed, however, 

 that fertilization did not take place. 



This experiment was performed four times, giving eight sets 

 in all. In six of these sets not a single egg segmented. In two 

 others a very few eggs segmented (6 per cent, in one, 5 per cent, 

 in the other), but this sometimes occurs in self-fertilized eggs 

 not treated in any special way. Moreover there may have been 

 contamination in the latter case. 



Another experiment similar in some respects to the last was also 

 carried out. The heart of one individual was opened and the 

 blood collected. The eggs of another individual were put into 

 this blood and allowed to stand. Later, sperm of the same indi- 

 vidual was added in sea-water, but no fertilization occurred in 

 one set and only one per cent, in the other. Check eggs were also 

 kept in this experiment to make certain that no sperm had acci- 

 dentally gotten into the blood. That none were present was 

 shown by the fact that no fertilization took place. It is evident 

 from this experiment that self-fertilization can not be brought 

 about by soaking the eggs in the extract from the ovary or in the 

 blood of another individual, although the somewhat high per- 

 centage of self-fertilized eggs that segmented in two cases after 

 treatment with the ovarian extract may have resulted from the 

 influence of the extract on the spermatozoa. 



If the spermatozoa are excited to greater activity by the pres- 

 ence of the eggs of another individual it seemed not improbable 

 that this might be directly observed. Therefore, I placed some 

 of the sperm with the eggs of another individual and more 

 of the same sperm with the eggs of the same individual, and 

 compared the two preparations under the microscope. The sper- 

 matozoa of Ciona are not very active as a rule, nor do they 

 accumulate in crowds around the eggs, as they do in many other 

 animals, or at least not to any marked extent. It seemed to me 

 in both cases that sometimes the spermatozoa were more active 

 immediately in the vicinity of the eggs, And in the spaces between 

 the follicle cells, but as they also show the same activity around 



