142 THE STORY OF LIFE'S MECHANISM. 



still contain potentially the organization of the 

 whole adult, or only one half of it? Is the 

 development of the egg simply the unfolding of 

 some structure already present ; or is the struc- 

 ture constantly developing into more and more 

 complicated conditions owing to the bringing of 

 its parts into new relations ? To answer these 

 questions experimenters have been engaged in 

 dividing developing eggs into pieces to determine 

 what powers are still possessed by the fragments. 

 The results of such experiments are as yet rather 

 conflicting, but it is evident enough from them 

 that we can no longer look upon the egg cell 

 as a simple undifferentiated cell. In some way 

 it already contains the characters of the adult, 

 and when we remember that the characters of 

 the adult which are to be developed from the egg 

 are already determined, even to many minute 

 details such, for instance, as the inheritance of 

 a congenital mark it becomes evident that the 

 egg is a body of extraordinary complexity. And 

 yet the egg is nothing more than a single cell 

 agreeing with other cells in all its general charac- 

 ters. It is clear, then, that we must look upon 

 organization as something superior to cells and 

 something existing within them, or at least with- 

 in the egg cell, and controlling its development. 

 We are forced to believe, further, that there may 

 be as important differences between two cells as 

 there are between two adult animals or plants. 

 In some way there must be concealed within the 

 two cells which constitute the egg of the starfish 

 and the man differences which correspond to 

 the differences between the starfish and the man. 



