THE CELL AND PROTOPLASM. 141 



the leading advocates of the cell doctrine, and 

 have beyond question been the inspiration of 

 the development of that doctrine. 



But certainly no such conception of the signi- 

 ficance of cell structure would longer be held. 

 In spite of the fact that the egg is a single cell, it 

 is impossible to avoid the belief that in some way 

 it contains the starfish. We need not, of course, 

 think of it as containing the structure of a star- 

 fish, but we are forced to conclude that in some 

 way its structure is such that it contains the 

 starfish potentially. The relation of its parts 

 and the forces therein are such that, when placed 

 under proper conditions, it develops into a star- 

 fish. Another egg placed under identical condi- 

 tions will develop into a sea urchin, and another 

 into an oyster. If these three eggs have the 

 power of developing into three different animals 

 under identical conditions, it is evident that they, 

 must have corresponding differences in spite of 

 the fact that each is a single cell. Each must in 

 some way contain its corresponding adult. In 

 other words, the organization must be within the 

 cells, and hence not simply produced by the 

 associations of cells. 



Over this subject there has been a deal of 

 puzzling and not a little experimentation. The 

 presence of some sort of organization in the egg 

 is clear but what is meant by the statement is 

 not quite so clear. Is this adult organization in 

 the whole egg or only in its nucleus, and especi- 

 ally in the chromosomes which, as we have seen, 

 contain the hereditary traits ? When the egg 

 begins to divide does each of the first two cells 



