42O E. E. JUST. 



is responsible for the failure during the latter part of the season 

 of shed eggs to fertilize. The failure of these eggs to fertilize 

 may, indeed, be due to other causes. Nevertheless the following 

 points warrant consideration for the assumption that blood is 

 responsible for this inhibition : 



First, the failure of fertilization is not due to the absence of 

 fertilizin. For eggs in blood liberate fertilizin (Lillie, '14). l 

 Secondly, washing removes the inhibition to fertilization, and this 

 is true of those eggs whose failure to fertilize is indubitably due 

 to the presence of blood. Thirdly, the inhibition decreases after 

 the eggs have remained in sea-water for some time. And, finally, 

 I have observed during several seasons that late in August Arbacia 

 females are frequently turgid with eggs from ruptured ovaries. 

 Such blood-soaked eggs are of low fertilization capacity. These 

 considerations point to a blood block, but they certainly do not 

 prove the case. 



Indeed, Oshima, likewise working with the egg of Arbacia in. 

 September, 1921, after I had left Woods Hole, has interpreted the 

 failure of eggs escaping through the genital pores of opened sea- 

 urchins to fertilize as due to what he calls a " dermal secretion." 

 So far as I can determine, Oshima' s sole criterion for calling this 

 substance a " dermal secretion " he could get very little of it 

 from dermal tissues tlienisclvcs, it seems is the fact that he got 

 it from the outside of the urchins. By the same token, eggs and 

 sperm that exude through the genital pores and lodge among the 

 spines an observation that every worker with sea-urchins has at 

 some time made are dermal secretions ! Oshima's " dermal se- 

 cretion," I very much suspect, is an excretion, if not actually fecal 

 material. And this suspicion is strengthened by the fact, which 

 Oshima points out, that uric acid is found in it. 



Moreover, against Oshima's interpretation that the " dermal 

 secretion " inhibits fertilization we have Lillie's extensive experi- 

 ments to the contrary. I believe with Oshima that he would have 

 ' reached an entirely different conclusion had he been able to " carry 

 out this series of experiments more fully and accurately." I 

 heartily concur with his conclusion that the action of the " dermal 

 secretion " seems to have no biological significance. 



1 I have additional evidence on this point. 



