572 FRANK R. LILLIE 



Fortunately the idea that the inhibitor operates by occupy- 

 ing an ovophile side-chain of the fertihzin is capable of a ready 

 test, for then it should be possible to neutralize the inhibiting 

 effect of the blood, which now becomes ex. hyp. a deviation 

 effect, by treating the inhibiting blood with free fertilizin. This 

 substance should bind all molecules of the inhibitor so that they 

 could no longer exert any deviating effect, their bonds for fertilizin 

 being already occupied. This experiment succeeds perfectly as a 

 matter of fact. 



Before citing the experiments in detail, I would like to dwell 

 a little more on their significance. In the first place a negative 

 result would go far to overthrow the entire theory, for then it 

 would become necessary to assume, if the theory were to be 

 retained, that the combination of fertilizin and inhibitor could 

 take place in the egg but not in the test tube, an exceedingly 

 improbable assumption. The positive result, actually obtained, 

 is in accord with the theory, and it is exceedingly difficult to frame 

 any other interpretation of such a result. The alternative point 

 of view would be to postulate a neutralization of a hypothetical 

 membrane effect of the inhibitor, a conception exceedingly diffi- 

 cult to support as we have seen, and now rendered doubly diffi- 

 cult through the neutralization of such effect by excess of a sub- 

 stance which by itself in high concentrations actually reduces 

 the percentage of fertilizations. Such an alternative interpreta- 

 tion appears to me impossible. 



The experiments 



July 21, 1913: The following substanees were prepared: (1) Fresh 

 filtered blood of male sea-urchins. (2) Filtrate from 15 cc. sea-water 

 plus 7.5 cc. ripe Arbacia eggs, i.e., an agglutinating solution in sea-water, 

 which gave an 8 second reaction with fresh sperm at 1/1600 dilution. 

 (3) Filtrate from 15 cc. of the same male blood as in 1, plus 7.5 cc. eggs; 

 i.e., part of the blood (1) saturated with the egg secretions. It gave a 

 10 second agglutinating test at 1/1600 dilution. 



Two drops of fresh sperm (50 per cent) were then stirred into 5 cc. 

 of each of the above and into (4) 5 cc. sea-water for control. These 

 sperm suspensions prepared at 10:50 a.m. were thus about 0.6 per cent. 

 One drop of double washed eggs was then added to each sperm suspen- 

 sion 1-4 at 11:45. 



