12 E. E. JUST. 



It is thus seen that eggs of high fertilization capacity fail to 

 fertilize if inseminated in the presence of certain concentrations 

 of blood. Not all eggs give results comparable to those in the 

 table. Thus during May, 1921, several samples of blood tested 

 showed very weak inhibitory power. In essentials, however, the 

 results are quite comparable to those obtained by Lillie in his study 

 of fertilization in Arbacia. Moreover, Lillie's interpretation of 

 the mode of action of the blood inhibitor is sustained by this work 

 on the egg of Echinarachnius, as will now be shown. 



Sperm of Arbacia readily agglutinate in mixtures of Arbacia 

 egg-water and blood as though the blood were absent. Lillie thus 

 concluded from this that the blood does not block the reaction 

 between the sperm-agglutinating substance (fertilizin) and the 

 sperm; the block comes between fertilizin and substances in the 

 egg. But it is at once apparent to the reader that this is not wholly 

 conclusive : the substance in blood that inhibits fertilization may 

 well do so by some action on the surface of the egg rendering 

 sperm attachment and penetration impossible. Thus it might well 

 be that sperm in the presence of blood and egg- water rich with 

 sperm agglutinin of high power agglutinate; but in ordinary in- 

 semination this amount of agglutinin is not present, nor is the 

 insemination made as heavy as the sperm suspensions must be to 

 detect the presence of agglutinin. In the inseminations usually 

 employed for fertilizing eggs agglutination of spermatozoa does 

 not occur ; instead, the spermatozoa stick to the egg. As a matter 

 of fact, sperm likewise stick to Echinarachnius eggs inseminated 

 in blood. The failure of such eggs to fertilize can not, therefore, 

 be attributed to the effect of blood in blocking the agglutination of 

 sperm to the egg. 



At first I considered this result as due to the poor quality of the 

 sperm ; that it was not so much an inhibition by blood as a failure 

 of fertilization. Subsequently it was found repeatedly that On 

 inseminating in the presence of blood spermatozoa are attached to 

 the eggs. Thus we have evidence to support the postulate offered 

 by Lillie as to the mode of action of blood inhibitor. This is 

 brought out again in the next group of experiments. 



