EFFECT OF X-RADIATION ON CUMINGIA EGGS. 2 19 



The behavior of the extra sperm in the experiment, however, 

 calls to mind the change in the activity of Arbacia fertilizin under 

 the influence of X-radiation (Richards and Woodward, 1915). 

 This secretion from. Arbacia eggs possesses the power of activating 

 sperm, and this property is affected by X-rays as follows: a 

 slight radiation (2 min.) increases its activity, a long one (7 min.) 

 lessens it, while an exposure of intermediate duration is practically 

 without effect. Since a solution of Arbacia fertilizin in sea water 

 (egg water) is definitely affected by irradiation, it is very prob- 

 able that the substance which escapes from the eggs into the 

 water would also be influenced by the irradiation before it passes 

 out of the eggs. 



The egg secretions of Cumingia and their properties have not 

 been investigated, but Miss Cobb (see Woodward, '18, p. 464) 

 "discovered that the eggs and egg water of Cumingia produce 

 positive chemotactic response on the part of the sperm." Miss 

 Sampson has found (unpublished) a secretion from Cumingia 

 eggs which agglutinates its own sperm into very small groups 

 of three of four sperm, and produces a very strong agglutination 

 of Arbacia sperm. 



In view of these facts and reasoning from the analogy, we are 

 tempted to explain the facts shown in Table VI. by assuming that 

 the fertilizin of Cumingia while yet in the egg was affected by the 

 irradiation in such a manner as to bring about the results shown. 

 The long radiations in each case where eggs were exposed, 15, 

 and Di5, show fewer extra sperm than the control which is to 

 be expected if the long exposure decreases the activity of the 

 substance as in the case of Arbacia fertilizin. Likewise in 3, a 

 short exposure, more sperm entered into than the control eggs. 

 This, too, is to be expected if the short irradiation activates the 

 fertilizin. D3 represents the count of too few eggs to be de- 

 pendable. In 63 and 615 where the sperm were radiated with 

 the result that an increased number entered the egg after the 

 short exposure and fewer than the control number are present, 

 we may be dealing with a similar effect of the irradiation upon 

 the sperm receptors (see Lillie, '19), although at the present time 

 there is not even an analogy upon which to base such an assump- 

 tion. 



