334 BIOLOGY 



himself will be transmitted to the subsequent generations. If 

 an individual should sustain the loss of an arm, it would affect 

 his own life, but would have no influence upon the germ sub- 

 stance which he has received from the egg, and which he is 

 simply holding in trust for the next generation: his offspring 

 will not be one-armed. So with any peculiarity developed 

 during life, as the result of life habits or as the direct result 

 of environment. Characters which are impressed simply upon 

 the individual himself will have no opportunity of being 

 transmitted to subsequent generations. 



Congenital and Acquired Characters. Thus it will be seen 

 that variations are of two distinct types: (1) variations which 

 appear in the germ plasm and which therefore affect subsequent 

 generations; (2) variations which appear in the body of the 

 individual and which are not in the germ plasm, and hence 

 cannot affect subsequent generations. These two types of 

 variations have been recognized for a long time, but they 

 were never sharply distinguished until Weismann's conception 

 of heredity brought them out in such clear contrast. Char- 

 acters which result from modification of the germ plasm, and 

 hence are inevitably transmitted by heredity, to-day are com- 

 monly called congenital characters. Congenital variations are 

 fixed in the germ plasm and are therefore inevitably trans- 

 mitted by the process of heredity. On the other hand, char- 

 acters which are developed as the direct result of the environ- 

 ment, such as loss of limbs, or changes resulting from food habits, 

 climate, etc., are commonly known by the name of acquired 

 characters. The term is not a good one, for all characters are 

 acquired at some time; but this name has been used in the 

 discussion of the last quarter of a century, for such variations. 

 From what has just been stated, it is evident that acquired 

 characters, if they do not become a part of germ substance, 

 will not be repeated in subsequent generations. Acquired 

 characters, therefore, which an individual animal or plant 

 develops as the result of the conditions of the environment in 



