244 Studies in the F/if/siolof/i/ of Fertilization 



TABLE IX. (46.-2.7.) 



Exp. 1. A'/o 

 Exp. 2. Pjq 

 Exp. 3. Ills 



Eggs from Kkks from ' own " 



water sptrm, washed 



\ :i (iiojjs s)K'im ... 9.T 70 



\ \ cc. spfiiii ... 100 100 



( 3 drops sperm ... 3 <1 



I 1 cc. spcnii ... II 4 



( .H drops sperm ... 40 18 



( 1 cc. sperm ... 82 64 



The Table shows that the egg.s whicli have been in the presence of 

 "own" sperm behave in subsequent cross-fertilization in the same way 

 after the "own" sperm has been removed by washing as they did in the 

 previous experiments when this was not done. This makes it extreinely 

 probable that the real reason for the diminished capacity for cross- 

 fertilization is a change brought about in the eggs by the sperm of the 

 same individual. 



An examination of Tables VIII and IX .shows that the change in 

 the eggs, as indicated by the lowered cross-fertilization percentages, is 

 comparatively small, and that when an excess of "foreign" sperm is 

 present, as in Table VIII, Exp. 2, and Table IX, Exp. 1, 1007„ of these 

 eggs can be fertilized. That the eggs can be cross-fertilized after the 

 treatment, although with rather less ease, does not mean that there 

 may not have been a large change in them, as regards their receptivity 

 to their "own" sperm. Whether this is so or not cannot be tested, as 

 our only criterion is that of comparing the extent to which they can be 

 cross-fertilized, with and without the previous treatment. The facts 

 certainly point, however, to the sperm having caused an alteration in 

 the eggs of the same individual, and to this alteration being at any rate 

 one of the means by which self-fertilization is effected. 



V. Comparison of the Subsequent Development of Eggs self- 



AND cross-fertilized UNDER VARIOUS CONDITIONS. 



1. Eggs cross-fertilized at different intervals after the reiiiuvul of 

 the genital products from the body of the animal. 



The foregoing investigations, concerning some of the conditions 

 which favour and limit the extent of self-fertilization, and the reasons 

 for the self-sterility itself bring the main part of this division of the 

 work to a conclusion. A considerable number of observations were, 

 however, also made on the subsequent development of eggs self- and 



