October 10, 1913] 



SCIENCE 



527 



fluid (blood) of the sea-urchin, especially of 

 ripe males and females, often contains a sub- 

 stance which absolutely inhibits fertilization 

 in the presence of any quantity of sperm, but 

 that this substance has no inhibiting effect at 

 all upon the sperm-agglutination reaction. It 

 does not enter into combination with the 

 spermophile side-chain. In other words, the 

 binding of the agglutinin by the sperm may 

 be complete, but in the presence of an inhib- 

 itor contained in the blood none of the usual 

 effects of insemination, no matter how heavy, 

 follow. 



The details of the exi)eriments upon which 

 the above statement depends are too complex 

 for consideration here. But they showed that 

 the effect is neither upon the egg alone nor 

 upon the sperm alone, for both may stand for 

 some time in the presence of this agent and 

 after washing be capable of normal behavior 

 in fertilization, though there may be some 

 decrease in the percentages. No poisonous 

 effect is involved on either sexual element. 



The next suggestion was fairly obvious, viz., 

 that the substance which we had been calling 

 agglutinin, on account of its effect upon the 

 spermatozoa, is in reality an amboceptor with 

 spermophile and ovophile side-chains, and that 

 the binding of the sperm activates the ovo- 

 phile side-chains which then seize upon egg 

 receptors and fertilize the egg. If this were 

 80, it is obvious that the spermatozoon is only 

 secondarily a fertilizing agent, in the sense of 

 initiating development, and that the egg is in 

 reality self-fertilizing, an idea which agrees 

 very well with the facts of parthenogenesis 

 and the amazing multiplicity of means by 

 which parthenogenesis may be effected. For 

 the agents need only remove obstacles to the 

 union of the amboceptor and egg receptor. 



The inhibiting action of the blood from this 

 point of view is a deviation effect due to 

 occupancy of the ovophile side-chain of the 

 amboceptor, either because the inhibitor in the 

 blood is an anti-body to the amboceptor or 

 because it possesses the same combining group 

 as the egg receptor. In such a case, the ovo- 

 phile group of the amboceptor, being already 



occupied by the inhibitor, fertilization could 

 not take place. 



Fortunately, this idea is susceptible of a 

 ready test; for, if the blood acts in this way 

 in inhibiting fertilization, all that is necessary 

 to neutralize the inhibiting action would be 

 to occupy the inhibitor by the amboceptor 

 (fertilizin) for which ex. hyp. it has strong 

 affinity. This experiment was repeated many 

 times in different ways with various dilutions, 

 and the result was always to lessen or com- 

 pletely remove the inhibiting action of the 

 blood. 



The plan of such an experiment is this: 

 to divide the filtered blood (plasma) in two 

 parts, one of which is used for control while 

 the other is saturated with fertilizin by addi- 

 tion of eggs. In ten minutes the latter are 

 precipitated by the centrifuge and the super- 

 natant fluid filtered. Fertilizations are then 

 made in graded dilutions of this and the con- 

 trol blood. In some cases the inhibiting 

 action of the blood was completely neutral- 

 ized, and in all largely neutralized. 



The results so far are in agreement with 

 the theory. But if it be true that the egg 

 contains its own fertilizing substance, it 

 might also be possible to induce parthenogen- 

 esis by increasing the concentration of this 

 substance to a certain point; though it is con- 

 ceivable that no increase in concentration 

 would break down the resistance that nor- 

 mally exists to union of the amboceptor and 

 egg receptors. As a matter of fact, Dr. Otto 

 Glaser^ has shown this summer that a certain 

 amount of parthenogenetic action may be in- 

 duced in Arhacia in this way. I have been in 

 consultation with Dr. Glaser during part of 

 his work and can confirm his statements. 



In connection with the assumption that the 

 sperm activates an already existing side-chain 

 of a substance contained in the egg itself, I 

 may be allowed to cite the following state- 

 ment of Ehrlich: 



The significance of the variations in affinity will 

 be discussed connectedly at a subsequent time. 

 We shall content ourselves here by pointing out 



2 Science, N. S., Vol. XXXVIII., No. 978, Sep- 

 tember 26, 1913, p. 446. 



