EGG-SECRETIONS OF ARBACIA AND ASTERIAS. 371 



by shaking, the eggs after two or three washings impart only a 

 weak agglutinating power to the supernatant water. This 

 however increases in the course of time. From this Lillie con- 

 cludes that the eggs produce the agglutinating substance. More- 

 over he has shown that they are the only tissue of Arbacia that 

 does produce this material. 



My own experiments show that the agglutinating substance 

 is located in greatest abundance in the jelly and that the eggs 

 also contain this material. As additional evidence it may be 

 stated that when eggs are inseminated with fairly concentrated 

 sperm-suspensions, the collection and activity of the spermatozoa 

 may be great enough to tear the outer jelly away from the egg. 

 When this occurs, one may suddenly observe great balls of sperm 

 apparently cast off from the eggs and forming huge agglutination 

 masses. In this instance many sperm also remain in contact 

 with the egg, which later shows a typical fertilization membrane, 

 and divides. This point is important in connection with the 

 mistaken idea that the outer jelly is essential for the appearance 

 of the fertilization membrane (*I3 4 ). 



In connection with the existence of agglutinin in the egg, I 

 may refer to experiments with egg-powder in which very ef- 

 fective agglutinations were secured. It cannot well be supposed 

 that every fragment of egg-powder has bits of dried jelly adhering 

 to it. 



4. The Mechanism of Agglutination. On this point Lillie's 

 inference based on the Nereis sperm, in which because of rel- 

 atively great size and slow movement, direct observation is 

 possible, can be substantiated by a variety of observations. 

 Lillie noticed that the agglutination is between the heads, and 

 that the tails, at least until the period of paralysis sets in, are 

 not visibly affected. "The adhesion of the heads demonstrates 

 some change in the membrane that renders them sticky" ('I3 1 , 

 p. 556), and direct observation showed "that in agglutinated 

 masses the heads of many of the spermatozoa are swollen into 

 spherical form and have lost the normal strong refringibility. 

 The change is in this case a very characteristic one indicating 

 a great change in permeability" (loc. cit.}. 



The capacity for influencing the permeability of cells is by 



