H. M. FucHS 



233 



the same concentration as the suspension of " own " sperm ; to (4), 4 cc. 

 of ditto. The results of these experiments are shown in Tabic I. 



The Table shows that in each of the e.xperiments an increase in the 

 concentration of " own " sperm caused an increase in the number of 

 eggs self-fertilized, the percentage in Exp. 3 being raised to 100, a 

 proportion which subsequent experiments proved to be uncommon. 

 The fertilizations of the eggs with " foreign " sperm demonstrate the 

 ease with which cross-fertilization is effected as compared with self- 

 fertilization by an approximately equal concentration of sperm, 100 °/^ 

 of the eggs segmenting in each experiment, even with the more dilute 

 sperm-suspensions. 



Further experiments were then carried out confirming this con- 

 clusion. The results are shown in Tables II, III and IV. The method 

 used in the experiments of Table II, which was the same as that used 

 in those of Tables III and IV, was as follows. 



Six dishes were prepared, containing equal amounts of water. To 

 the first three were added approximately equal amounts of eggs E to be 

 selfed, and to the last three, approximately equal' amounts of eggs of 

 another individual F to be crossed. Fertilization was effected by the 

 addition to each dish of the amounts of sperm-suspension e given in 

 the Table. In this case the comparison between the proportion of eggs 

 selfed and the proportion crossed with the same amount of sperm was 

 exact, since the same sperm-suspension was used in each fertilization. 



Cross 



Eje 



TABLE II. (8.9.1.) 



Self-fertilization 



2 drops 

 sperm 



2 



25 drops 

 sperm 



24 



10 cc. 

 sperm 



100 



Cross-fertilization 



Cross 

 Fje 



2 drops 

 sperm 



100 



25 drops 

 sperm 



100 



10 cc. 

 sperm 



100 



Cross 

 Gl9 



1 drop 

 sperm 



TABLE in. (8.9.1. 



Self-fertilization 



5 drops 

 sperm 



20 drops 

 sperm 



100 drops 

 sperm 



11 



ajg 



1 drop 

 sperm 



100 



Cross-fertilization 



5 drops 

 sperm 



100 



20 drops 

 sperm 



100 



100 drops 

 sperm 



100 



TABLE IV. (lO.U.l. 



