GERM-PLASH AXD BODY 



from body-cells, but from germ-cells. This 

 relationship first pointed out by Weismann 

 may be expressed in a diagram, as in Fig. 9. 

 Only such environmental influences as directly 

 alter the character of the germ-cells will in 

 any way influence the character of subsequent 

 generations of individuals derived from those 



Line of succession. 



Line of inheritance. 

 C 



FIG. 9. Diagram showing the relation of the body (<S) to the 

 germ-cells (G) in heredity. (After Wilson.) 



germ-cells. Body (or somatic) influences are 

 not inherited. This knowledge we owe largely 

 to Weismann, who showed experimentally that 

 mutilations are not inherited. The tails of 

 mice were cut off for twenty generations in 

 succession, but without effect upon the char- 

 acter of the race. Weismann also pointed out 

 the total lack of evidence for the then current 

 belief that characters acquired by the body 

 are inherited. The correctness of his view that 

 body and germ-cells are physiologically distinct 



29 



