566 ^ FRANK R. LILLIE 



The agglutination of spermatozoa is, of course, in itself of no 

 significance for the problem of fertihzation; the spermatozoa 

 unite in fertilization with the egg, not with one another. The 

 agglutination reaction is, however, an indicator of an important 

 change in the spermatozoon in the presence of egg secretions, and 

 therefore evidence of a change that any spermatozoon must 

 undergo when it comes in contact with the egg. The adhesive 

 property that the sperm develops under these circumstances may 

 be an important factor in binding the sperm to the egg until it 

 can be incorporated. But, if the reaction be specific, it is much 

 more than this; it is evidence of an intimate chemical combination 

 of sperm and egg constituents which begins at the very moment 

 of union. 



Von Dungern's experiments ('02) are the only ones, so far as I 

 know, in which the production of sperm agglutinins by ova was 

 investigated, and he discovered only hetero-agglutinins, no iso- 

 agglutinins. He did, indeed, describe the loss of motility of 

 spermatozoa in egg-extracts of the same species, but he entirely 

 missed the phenomenon of agglutination and its reversal. He 

 reveals the reason for this failure by his remark that he always 

 examined for the effect of the 'egg-poison' about half-an-hour 

 after its addition to the sperm; but the phenomenon of agglutina- 

 tion and its reversal are completed in about five minutes. 



Von Dungern also made experiments on the production of 

 immune sera by injection of ova and spermatozoa separately 

 into rabbits, and found that both caused the production of a 

 sperm agglutinin in the rabbit's serum. From this he concludes 

 that both kinds of reproductive elements possess chemically 

 identical complexes of molecules in the protoplasm. While this 

 may be admitted as at least a very probable conclusion, his farther 

 conclusion that fertilization does not depend upon any specific 

 antagonism between ovum and sperm, b.ut is conditioned by the 

 similarity of their protoplasms, is not well founded, for the egg is a 

 very complicated chemical system, and it certainly contains mole- 

 cules antagonistic to sperm, even if, as Von Dungern's experi- 

 ments indicate, it also contains some that are not. 



