HEREDITY. 



441 



new character acquired by the soma under the appro- 

 priate stimulus, and let a represent the same charac- 

 teristic as it is impressed on the germ-plasma of the 

 same individual at the same time, and in consequence 

 of the same stimulus. The history of the acquisition 

 and incorporation of newly acquired characters by the 

 line of descent originating with the species S-\-g, may 

 be represented as follows, for successive generations, 

 which are numbered i, 2, 3, etc. 



/ SA 



Fig. 120. Diagram explanatory of Diplogenesis. 



Under the appropriate stimulus the soma S acquires 

 A, and the germ plasma g the identical a 1 as the first 

 stage. The character A a 1 being only inheritable via 

 the germ-plasma, it is represented by a 1 in the second 

 stage or generation, where it appears as an addition 

 to the characters of S and g, so that the soma of the 

 second generation is represented by the expression 

 Sa l , and the germ-plasma by g(a l ) ; (on the supposi- 



