Exceptions to the Law of Heredity. 209 



low minds that a great and beautiful object loses its charm by 

 losing somewhat of its mystery, and discovering a part of the 

 secret process whereby nature has given it birth.' 



If we reflect on the preceding facts, we shall, I think, agree that 

 the exceptions to heredity, great as they may be, are less embarrass- 

 ing than at first they seemed. Suppose two children as different as 

 possible in psychical constitution : it is probable that if we could 

 ascend to the causes of these differences, we should find them very 

 simple. But unfortunately there is no mental chemistry by which 

 we can transform these probabilities into certainty. 



v. 



We will now examine another cause of deviation from hereditary 

 type, another source of diversity in the act of generation the 

 metamorphoses or transformations of heredity. This case is more 

 simple than the preceding, to which, indeed, it may be referred as 

 a species to its genus. Here we can trace the course of heredity, 

 because the transition is not now from contrary to contrary, but 

 from like to like ; no longer from genius to idiocy, from virtuous 

 father to debauched son ; but from epilepsy to paralysis, from 

 eccentricity to insanity. We might say that in the present case 

 there are partial exceptions, and in the preceding case total excep- 

 tions, were it not that we are anxious always to keep in view the 

 important truth that there is never a total exception to heredity, the 

 exceptions to it never going beyond the individual characteristics. 



The study of the transformations of heredity has been made in 

 detail by Dr. Moreau, of Tours, in his Psychologic Morbide. To 

 that work we refer the reader for particulars, and here extract from 

 it only the facts of most interest for psychology. 1 



* It shows an incorrect conception of the law of heredity,' says 

 he, ' to look for a return of identical phenomena in each new 

 generation. There are some who have refused to subject mental 

 faculties to heredity, because they would have the character and 

 intelligence of the descendants exactly the same as those of the 

 progenitors ; they would have one generation the copy of the 

 other that went before it, the father and son presenting the spec- 



1 Physiologie Morbide, pp. 108193. 



