THE CELL AND PROTOPLASM. 12 1 



But certainly no such conception of the signifi- 

 cance of cell structure would longer be held. In 

 spite of the fact that the egg is a single cell,jt 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 starfish, 

 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 starfish. An- 

 other egg placed under identical conditions will 

 develop into a sea urchin, and another into an 

 oyster. If these three eggs have the power of de- 

 veloping into three different animals under iden- 

 tical 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 puz- 

 zling and not a little experimentation. The pres- 

 ence of some sort of organization in the egg is 

 clear but what is meant by this statement is not 

 quite so clear. Is this adult organization in the 

 whole egg or only in its nucleus, and especially 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 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 al- 

 ready present; or is the structure constantly de- 

 veloping into more and more complicated condi- 



