i VARIATION AND HEREDITY 87 



acquired characters are agreed, namely, that certain in 

 fluences, such as that of alcohol, can affect at the same 

 time both the living being and the germ-plasm it con 

 tains. In such case, there is inheritance of a defect, 

 and the result is as if the soma of the parent had acted 

 on the germ-plasm, although in reality soma and plasma 

 have simply both suffered the action of the same cause. 

 Now, suppose that the soma can influence the germ- 

 plasm, as those believe who hold that acquired characters 

 are transmissible. Is not the most natural hypothesis 

 to suppose that things happen in this second case as in 

 the first, and that the direct effect of the influence of 

 the soma is a general alteration of the germ-plasm ? 

 If this is the case, it is by exception, and in some sort 

 by accident, that the modification of the descendant 

 is the same as that of the parent. It is like the 

 hereditability of the alcoholic taint : it passes from 

 father to children, but it may take a different form 

 in each child, and in none of them be like what 

 it was in the father. Let the letter C represent 

 the change in the plasm, C being either positive 

 or negative, that is to say, showing either the gain 

 or loss of certain substances. The effect will not 

 be an exact reproduction of the cause, nor will the 

 change in the germ-plasm, provoked by a certain 

 modification of a certain part of the soma, determine 

 a similar modification of the corresponding part of the 

 new organism in process of formation, unless all the 

 other nascent parts of this organism enjoy a kind of 

 immunity as regards C : the same part will then 

 undergo alteration in the new organism, because it 

 happens that the development of this part is alone 

 subject to the new influence. And, even then, the 

 part might be altered in an entirely different way 



