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SCIENCE 



[N. S. Vol. XXXVIII. No. I 



that an understanding of the phenomena of im- 

 munity is impossible without the assumption that 

 certain haptophore groups become increased or 

 decreased in their chemical energy, owing to 

 changes in the total molecule. Chemically, such 

 an assumption is a matter of course.' 



This principle might explain the activation 

 of the fertilizing amboceptor by the sperm. 



The question will of course be raised 

 whether there is not another and simpler in- 

 terpretation of the facts. There are three 

 general classes of these facts : (1) the sperm 

 agglutination phenomena, and the apparent 

 necessity of the agglutinating substance for 

 fertilization; (2) the presence of an inhibit- 

 ing agent in the blood, especially of ripe males 

 and females; (3) the neutralization of this 

 inhibiting agent by the agglutinating agent 

 (amboceptor). It may be questioned whether 

 these facts have the particular causal nexus 

 that I have given them. But I think it would 

 be difficult to construct a theory taking account 

 of all the facts which would differ essentially 

 from that presented here. 



The theory is really extremely simple in its 

 character, and the facts on which it rests are 

 readily tested. It has proven a most valuable 

 working hypothesis; indeed, many of the facts 

 referred to were discovered only after the 

 theory was formed. It has the advantage of 

 offering one theory for initiation of develop- 

 ment whether by fertilization or by partheno- 

 genesis. It is capable of explaining the whole 

 range of specificities in fertilization by as- 

 suming a specific fertilizin for each species. 

 It furnishes the foundation for the chemical 

 conceptions necessary to any theory of fertili- 

 zation, and it is susceptible of experimental 

 test. 



It will be seen that inhibition of fertiliza- 

 tion may occur by block in any part of the 

 mechanism. 



1. Through loss of fertilizin by the egg. 



2. Through occupancy of the sperm recep- 

 tors. 



3. Through occupancy of the egg receptors. 



4. Through occupancy of the ovophile side- 

 chain of the amboceptor (fertilizin). 



"'Collected Studies in Immunity," p. 220. 



5. Through occupancy of the spermophile 

 side-chain group. 



Of these I have shown the occurrence of the 

 first, fourth and fifth in Arbacia. The first in 

 the case of long-washed eggs ; the fourth in the 

 ease of the inhibitor contained in the blood; 

 the fifth is, I believe, the mechanism for pre- 

 vention of polyspermy. 



The mechanism of fertilization appears to 

 be the same in Nereis, though I have not a 

 complete set of data. However, the data that 

 I have are in accord with the theory, and will 

 be described in the complete paper. 



I should perhaps state specifically that the 

 location of the fertilizin is in the cortex of the 

 egg. 



It seems to me probable that the activation 

 of the fertilizin is by no means confined to 

 that bound by the single penetrating sperm, 

 but that activation once set up spreads around 

 the cortex. The supernumerary spermatozoa 

 that fail to enter the egg may also play a 

 part by setting up centers of activation. In 

 this connection Glaser's contention that sev- 

 eral spermatozoa at least are necessary for 

 fertilization is of great interest. The nature 

 of the effect of the activated fertilizin on the 

 egg is analogous in some respects to a super- 

 ficial cytolysis, in this respect agreeing with 

 Loeb's theory. But the " lysin " is contained 

 in the egg, not in the sperm, as Loeb thought; 

 if cytolysis is involved, it is a case of auto- 

 cytolysis. This may involve increase of per- 

 meability, the effects of which R. S. Lillie has 

 especially studied. I mention these possibil- 

 ities in order to point out that the conception 

 contained in this paper is not in conflict with 

 the well-established work of others. 



In conclusion, I may point out that the 

 theory assumes a form of linkage of sperm and 

 egg components by means of an intermediate 

 body that may find a place in the study of 

 heredity. The detailed experiments will be 

 published later. 



Feank E. Lillie 



Marine Biological Laboratory, 

 "Woods Hole, Mass., 

 September 1, 1913 



