Are there Laws of Heredity ? 143 



If we apply Maupertuis' argument to a few cases of psycho- 

 logical heredity, for instance mental disorder, or some special 

 talent (for painting, or music) persisting through three or four 

 generations, it is easy to see what becomes of Buckle's objection. 



in. 



The greater part of these objections would never have been 

 raised, were it not for the serious error of reasoning only from the 

 exceptions. To treat the question fairly, it ought first of all to have 

 been properly stated, that is to say, the fact of heredity should 

 have been considered, not partially, but in its whole extent in the 

 entire domain of life, as we here propose to do. 



In order to proceed logically, we should in the first place have 

 to determine what is meant by species. We will not enter into 

 this very difficult question. It will be enough for us to lay down 

 a few very simple, unquestionable and elementary facts, which will 

 be admitted by all. 



When we compare together two living beings that is to say, two 

 sums of attributes and find that these two beings possess in common 

 a very large number of essential attributes, differing only in those 

 which are secondary, so that the two beings may be regarded as 

 very much alike, we say that they are of the same species. The 

 many essential characteristics possessed by them in common we 

 call specific ; the few accidental characters which differentiate 

 them we call individual. Thus, for instance, two individuals of the 

 human species possess in common very many essential characters, 

 being organic, vertebrate mammals, with all that is thereby implied, 

 having senses, physiological or psychological functions, such as 

 sensation, memory, imagination, reason. But they differ from one 

 another in accidental or individual characteristics, as that the 

 muscular system common to both is in the one very well developed, 

 very slightly in the other ; that the faculty of memory common to 

 both is weak in the one, and very strong in the other ; that the 

 faculty of reason common to both does not in the one go beyond 

 the simplest acts, while in the other it includes the highest 

 abstractions. 



Now, by the act of generation, in which heredity has its origin, 

 every creature produces beings like itself. In the lower forms of 



