146 A. RICHARDS AND A. E. WOODWARD. 



efficiency of the agglutinin contained In fertllizin, like pepsin 

 (Euler, p. 132) varies with the square root of the concentration. 

 If the efficiency is measured by the number of seconds the sperm 

 remain agglutinated, and the concentration is measured by units 

 of strength, the curves in Figs. 1,2, and 3 are obtained for the 

 readings of July 14, August 10, and August 11, respectively. 

 The average is shown in the dotted line of Fig. 4. If an equation 

 is worked out for this curve, we obtain y"^ = iix where y repre- 

 sents the efficiency and x the concentration. This equation is 

 plotted as a solid line on Fig. 4. In the higher dilutions, of which 

 a greater number of values were averaged, and where readings 

 could be made more accurately, the curves coincide very closely. 

 In the less dilute portion the coincidence is not so marked, but Is 

 still within the limits of experimental error. 



The writers are not now able to offer an opinion as to whether 

 or not fertllizin has the character of an enzyme. The coin- 

 cidence, however, in the behavior of this substance, when 

 treated by x-rays, to that of true enzymes, is indeed striking. 



While the nature and composition of fertllizin are as yet 

 unknown, it is a cell-extractive which is capable of undergoing 

 changes under the action of experimental agents such as radia- 

 tion by x-rays. Possibly it, or its forerunner, exists in the 

 egg in combination. Among the other constituents of Arhacia 

 eggs, this substance stands as one which, at least in solution 

 In sea water, is able to bring about certain reactions on 

 the part of sperm, and these reactions are subject to experi- 

 mental modification. This justifies the inference that this sub- 

 stance or perhaps some similar one within the egg may be 

 capable of undergoing modification in its relations to the various 

 intra-cellular activities. 



In this modification we may look for the seat of part of the 

 changes which are brought about in living tissues and especially 

 egg cells by radiation. The Hertwigs, Packard and others have 

 shown that the chromatin of such cells is affected, and there is 

 good evidence that the cytoplasm as well is influenced. Changes 

 in their activity have also been demonstrated in the case of 

 enzymes. These experiments add still another to the list of 

 substances which are affected by the action of x-rays. It is 



