68 EVOLUTION, SOCIAL AND ORGANIC 



eluding man, into two distinct kinds; the 

 somatic, or body cells and the germ, or re- 

 productive cells. These germ cells are, so to 

 speak, batteries in which are stored a sub- 

 stance which Weismann calls germ-plasm. 

 A minutely small portion of this germ-plasm 

 from an individual of one sex, mixed with a 

 similar portion from an individual of the other 

 will produce a new individual. But — and 

 here comes the keystone of Weismann's arch 

 — only a portion of the mixed germ-plasm is 

 used up in the composition of the new indi- 

 vidual; the rest is stored away in the germ- 

 cells of the new individual for further repro- 

 duction when the time arrives. The only rela- 

 tion that this reserved germ-plasm has with 

 the body cells of the new individual is that it 

 is provided by them with room and board. 



Thus, according to Weismann, from genera- 

 tion to generation, there is an unbroken stream 

 of germ-plasm, and this constitutes his cele- 

 brated theory of "The Continuity of Germ- 

 Plasm." Granted this theory as a premise, 

 and Weismann's conclusions cannot be gain- 

 said. This germ-plasm being the sole "carrier 

 of heredity," nothing that happens to the so- 

 matic or body cells can be transmitted to the 

 progeny. 



Darwin had put forward a theory of hered- 



