Self -Fertilization Induced by Artificial Means. 141 



long time, then taking out some sperm from the same individual, 

 first making it active by placing it in sea-water, and then putting 

 it into the water in which the eggs have stood. On the hypothesis 

 these sperm should soon be brought to rest, and if then the eggs 

 of another individual are added, they should not be fertilized, o 

 at least not in the same proportion as when the sperm is taker 

 directly from the oviducts, put into sea-water, and then added t 

 the eggs. 



THE INFLUENCE OF ETHER ON CROSS-FERTILIZATION. 

 EXPERIMENTS WITH CIONA. 



My first experiments with ether were made in order to deter- 

 mine whether when eggs are etherized it might not be possible to 

 self-fertilize them. The results turned out somewhat differently 

 from what I had anticipated, for although I found that it was 

 possible to self- fertilize the eggs in ether-solutions, the result 

 seemed to be due to the action of the ether on the sperm rather 

 than on the eggs. 



The experiment was first made with Cynthia, which in most 

 cases has very sluggish spermatozoa. I observed that the first 

 effect of the ether was to make the sluggish sperm very active, and 

 even greatly quickened the activity of already active sperm. Fur- 

 thermore I found that spermatozoa that scarcely moved at all 

 in sea-water became active in the ether-solutions. Finally I found 

 that in ether-solutions of certain strengths the eggs of Cynthia and 

 of Ciona could be self-fertilized. The eggs behave in this respect 

 so capriciously that I was obliged to carry out a large number of 

 experiments in order to determine the conditions that lead to the 

 self-fertilization of eggs in ether-solutions. The outcome was 

 only partially satisfactory, but the experiments opened up a field 

 for research, in which it may be possible to obtain further results 

 of interest. 



The experiments with ether were carried out as follows : At 

 first I used a nearly saturated solution of ether and diluted it a 

 half, or a fourth, etc. In the later experiments I used solutions 

 of known strength. It was found by trial that the solutions were 

 effective between 0.25 and 5 per cent. Some of the results may 

 now be given in detail. 



