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FRANK E. LILLIE 



must be attributed to this, which is indeed the only assumption 

 consistent with the other known facts. 



Now if the agglutinating substance protects from the inhibitor 

 by occupying its combining group, it would be logical to expect 

 to find in some tissue of the species another kind of molecule 

 possessing an identical side-chain and hence equally capable of 

 protecting against the inhibitor. Such a substance was found 

 in the shell but not in the intestine. A sample experiment may 

 be cited. 



August 2, 1913 : A large quantity of blood was collected from females, 

 and the serum filtered. (A) One part set aside. (B) A second part 

 was saturated with the agglutinating substance by addition of eggs; 

 B tested to 1/3200; (C) To a third part was added a large quantity of 

 the shell and peristomes of the sea-urchins used: B and C filtered again. 



Fertilizations were then made in 0.2 per cent sperm suspensions in 

 identical concencrations of each in sea-water as sho^vn in table 15. 



The conclusion would seem to be that shell secretions (poison 

 from pedicellariae?) protect against the inhibitor in the blood. 

 The inhibitor was not very strong in this case, and test of C 

 showed that it contained a small quantity of agglutinating sub- 

 stance owing, as sometimes happened, to injuries to the ovaries 

 in collecting the blood, but there did not seem to be enough (7 

 second reaction undiluted) to influence the result. 



The above result was obtained in an attempt to meet the 

 possible objection that the inhibiting action of the blood might 

 be due to the inclusion of poison from pedicellariae. It appears, 

 on the contrary, that shell-secretions decrease the inhibiting 

 action of the blood, an entirely unexpected result. 



