INITIATION OF DEVELOPMENT IN OLETOPTERUS. 57 



oxidation rate for a time, and hence are accompanied by matura- 

 tion. 



R. S. Lillie ('08) says of the star-fish egg, "Suppression of 

 oxidative combined with acceleration of hydrolytic and reducing 

 processes is indicated as a condition of the initiation process in 

 these eggs." Loeb ('09), in commenting on Lillie's conclusion, 

 suggests that suppression of oxidation in the egg has its beneficial 

 effect not by allowing anaerobic processes which in themseht- 

 are of importance to the development, but by giving the egg time 

 to recover from the injurious effects of membrane formation 

 before preceding to further development. 



Another body of observations given in the experiments should 

 be mentioned here. With nearly all agents employed, the longer 

 exposure to the agent or the higher concentration of it, are pre- 

 judicial to maturation. On the other hand, production of 

 swimmers occurs in larger percentages with high concentration 

 and long exposure. If, as suggested, the course of development 

 is composed of two rather distinct sets of reactions, the one 

 accompanying maturation and concerned mainly with hydrolyses, 

 the other resulting in differentiation and requiring oxidation 

 processes, then it seems reasonable to suppose that an agent 

 which calls out both maturation and differentiation calls out 

 both sets of reactions, the one gaining force a little later than 

 the other. The two processes take place in their normal relation 

 when a certain concentration and time is used, but when this 

 concentration or time is increased, the normal time relation be- 

 tween the two is interfered with and the second reaction arises 

 before the first is completed. That is, the hydrolyses become 

 obscured by the oxidative processes which always accompany 

 differentiation. If these oxidative processes be of high enough 

 rate to start up the processes that lead to differentiation more 

 rapidly than the hydrolyses are forwarding the processes leading 

 to maturation, then obviously the later developmental phe- 

 nomena may come in and cut short the maturation phenomena. 1 



1 This actually seems to be the case when the second maturation spindle is 

 apparently drawn down toward the center of the egg (as the female pronucleus 

 would be, normally) before mitosis has been completed and the second polar body 

 thrown off. 



