294 RALPH S. LILLIE. 



rise to an Individual of the same species; and we must therefore 

 be prepared to find among the earhest chemical changes asso- 

 ciated with development, interactions of a specific kind — i. e., 

 specific in the sense in which the interaction of antigen and anti- 

 body is specific — between complex substances already present In 

 the egg. There is now definite experimental evidence that such 

 reactions do in fact constitute an essential part of the fertilization- 

 process.^ Specific substances which apparently unite in fertiliza- 

 tion (since after fertilization they are no longer demonstrable) 

 are present in the unfertilized mature egg; one of these ("fer- 

 tilizin") may be largely removed from the egg by washing, and 

 when this is done fertilization is prevented. If such specific 

 unions are essential to fertilization, we must conclude that the 

 specific substances concerned in this process are in some way 

 kept from interaction in the resting mature egg, and that the 

 activating agent removes this hindrance to interaction. The 

 question which I wish briefly to discuss in this section relates 

 to the nature of this inhibiting condition, and the manner in 

 which the activating agent effects its removal. 



The nature of the effects following exposure of unfertilized 

 eggs to temperatures of 30°-35° indicates clearly that activation 

 does not depend on simple acceleration of some chemical process, 

 e. g., oxidation, which is already proceeding in the egg, since In 

 this case the temperature-coefficient of the activation-process 

 would presumably show the usual value of Qio = 2-3. It is 

 also evident that heat-coagulation is not concerned, since these 

 temperatures are too low, and the readiness with which the 

 activation process can be arrested by cooling and renewed by a 

 second warming shows that its basis is some effect which is com- 

 pletely reversible by change of temperature. These character- 

 istics, high temperature-coefficient and reversibility with change 

 of temperature, are however shared by the typical melting and 

 gelation (sol-gel transformation) exhibited by solutions of gela- 



best evidence of this. The morphological characters of crystals and crystal-aggre- 

 gates varies with their chemically specific ("species-specific") character in a 

 definite and constant manner. It is fair to assume that the influence of these 

 compounds in determining organic structure depends largely on the kind of aggre- 

 gates they form. Cf. Reichert: Science, 1914, N. S., Vol. 40, page 649. 

 ■ Cf. F. R. Lillie, Journal of Experimental Zoology, 1914, Vol. 16, p. 523. 



