104 BIOLOGY AND SOCIAL PROBLEMS 



inherited is a most doubtful biological propo- 

 sition. 



The clarification of this whole matter, and 

 the present attitude of the majority of biolo- 

 gists toward it, are the results chiefly of Weis- 

 mann's work. Weismann pointed out very 

 clearly that the multitude of cells that arose 

 by the division of the egg cell, and that 

 eventually constituted the body of an adult 

 animal, could be grouped into two sets, the 

 somatic cells and the germ cells. The somatic 

 cells are represented by those cells that give 

 rise to skin, bone, muscle, nerve, and other 

 non-reproductive tissues. They constitute the 

 great mass of the body and carry on all its 

 functions except that of sexual reproduction. 

 The germ cells are those that give rise to 

 sperm cells or egg cells, and that are there- 

 fore primarily concerned with reproduction. 

 Both the germ cells and the somatic cells in 

 any individuals are descendants of the egg 

 cell from which that individual arose, but they 

 are not derived one from the other. Germ 

 cells are cells that are differentiated directly 

 from certain of the unmodified cells that re- 

 sult from the division of the egg cell and 

 never from cells that begin to show a tend- 



