80 THE BIOLOGICAL PROBLEM OF TO-DA Y 



process of development according to a plan pre- 

 arranged in its minutest details, and a passive 

 reserve army ordered into quiescence and carried 

 as baggage ? 



But here we come upon the scarlet thread that 

 continuously has traversed the theory of germplasm 

 in all its changes. Weismann attaches the greatest 

 importance to the distinction. The twofold nature 

 of the process of development is a cardinal point 

 in his theory, linked to his doctrine of immortality 

 for unicellular organisms and germ- cells and 

 mortality for somatic cells. 



Between somatic cells and reproductive cells 

 Weismann places a gulf that cannot be bridged. 

 Only the reproductive cells contain real germ- 

 plasm, and only these contain the conditions for 

 maintaining the species, as they alone serve for 

 the starting of new generations of development. 

 The somatic cells, on the other hand, are endowed 

 only with fragments of germplasm, and hence they 

 are incapable of preserving the species, and are 

 doomed to death. The reproductive cells, like 

 unicellular organisms, are regarded as immortal, 

 the somatic cells as mortal, According to Weis- 

 mann, cells cannot pass from the one category to 

 the other. 



As I see Nature, this contrast has been arti- 

 ficially reasoned into her. From several reasons, I 

 do not think that it exists. In the first place, 

 I consider that the facts I have given show the 

 hypothesis of a differentiating division of cells and 

 germplasm to be not proven and arbitrary. Next, 



