152 Heredity. 



sympathetic, and the whole nerve-system of the organic life : on 

 this depend internal sensibility and the sentiments. 



Each of these two lives would have the faculty of reproduction ; 

 consequently the transmission of the external life would imply the 

 transmission of the intelligence, while the transmission of the 

 internal life would imply that of the sentiments. 1 



Gall and his disciple Spurzheim, rejecting these doctrines, main- 

 tained an opinion which results logically from their system that 

 the analogy in the conformation of the various regions of the 

 cranial arch implies analogous psychological constitution. ' It has 

 been always observed,' says Gall, ' that when brothers and sisters 

 resemble one another, or their father and mother, in the shape of 

 the head, they also resemble each other in psychical and mental 

 qualities.' 



We may fairly consider that, since every one of these doctrines 

 is supported by a large number of facts, they all may be esteemed 

 partial generalizations; but since they are all open to many 

 exceptions, none can be accepted as a total generalization. Thus 

 is theory confirmed by experience : reasoning deductively, we 

 arrived at the conclusion that the perfect law of heredity would 

 never be realized ; and now the examination of the facts shows 

 that no empiric formula attains the breadth of a general law. 



The only thing that results clearly from this conflict of doctrines 

 is, that in point of fact there is always a preponderance of one of 

 the parents. 



In the case of direct heredity, the child is always more specially 

 like either the father or the mother. 



This preponderance, moreover, is never exclusive, as will appear 

 hereafter, from some curious facts. In spite of appearances, the 

 heredity of parents to children is never unilateral, but always 

 bilateral. The phenomena of reversionary heredity prove that, 

 although the influence of one of the parents on the child may 

 seem abolished, it never is annihilated, and thus the law of equality 

 of action is as far as possible realized. 



The phenomena of cross-breeding confirm what has been said. 

 Anthropologists have drawn up tables wherein the influence of the 



1 Dsla Generation, pp. 130, 131. 



