148 T. H. Morgan. 



great deal of it; hence, no doubt, the excellent results in the first 

 column. What is especially significant is that the best results 

 were obtained when the eggs and the sperm were put at the same 

 time into the solution together. This may mean the ether has 

 some effect on the eggs as well as on the sperm, or that the most 

 effective period of activity for the sperm is immediately after 

 it comes into contact with the ether. My experiments do not 

 sufl^ce to settle this point, but that the spermatozoa are still 

 capable of cross-fertilizing, after they have been in the ether 

 for some time, is shown by the following result. After four hours 

 the eggs of the first individual were mixed with the eggs and the 

 sperm of the second individual. Later it was found that all 

 the unsegmented eggs had been fertilized. The ether had no 

 doubt largely evaporated. 



The preceding twelve experiments with ether-solutions gave 

 definite results, although in a few cases the number of eggs self- 

 fertilized was small. It should be stated that there were ten 

 other individuals in which self-fertilization in ether did not take 

 place. This does not detract, I think, from the value of the 

 successful experiments, because, as has been shown, the sperm 

 is sometimes incapable of fertilizing even the eggs of another 

 individual. The following experiments were carried out in order 

 to examine this question further. It will be observed that parallel 

 experiments with ether were also performed. 



In each series five individuals were used. The eggs of each 

 were fertilized with the sperm of every other individual. The 

 following scheme shows the order in which the eggs were crossed. 

 An individual having been opened, the eggs were removed from 

 its oviduct and distributed in five dishes, A-A. Another individual 

 was then opened (using, of course, different scissors, pipettes, etc.) 

 and Its eggs distributed to the next line of dishes, B-B. The same 

 method was followed for the other three individuals. The sperm, 

 a, of the first individual was then taken out and put into a small 

 amount of water. It was then distributed to one set of eggs from 

 each of the other Individuals, B, C, D, E; then the sperm of B 

 was taken out and applied to another set of eggs. The process 

 was repeated until all the eggs were supplied with sperm. The 



