2 3 



We must, therefore, regard heredity and evolution as 

 inter-dependent and inseparable, as without heredity every 

 change of modification of any kind could only exist tran- 

 sitively, and would inevitably cease with the individual ; 

 and without evolution heredity could only necessitate the 

 " monotonous conservation of the same types, fixed once 

 for all." Life and variation are rendered possible by 

 evolution and heredity, the former producing modifications 

 which habit fixes in the individual, and heredity perpetu- 

 ates in the race. As Ribot says : " These modifications, 

 as they accumulate, and in course of time, become organic, 

 make new modifications possible in the succession of 

 generations. Thus heredity becomes in a manner a crea- 

 tive power." 



/" Heredity in an individual consists of qualities both 

 'physical and psychical, which may be denominated 

 (ancestral, parental, and acquired. The latter qualities are 

 without doubt transmissible, notwithstanding the fact that 

 in many cases, especially when a race is left to itself, such 

 deviation of type has, apparently, a tendency to revert to 

 the normal state. Independently of some exceptional and 

 reversional cases, it is a well-established fact proved by 

 the phenomena of physiological heredity, as detailed in 

 innumerable instances of the transmissibility of acquired 

 modifications that by careful selection breeders are 

 enabled not only to fix but to perpetuate certain physical 

 characters. When those animals possessing such acquired 

 modifications are " left to themselves," there is undoubtedly 

 a tendency to revert to the primitive type ; but as the art 

 of the breeder fixes them in the lower animals, so can they 

 be perpetuated in man under certain definite conditions. 

 " Thus there is established in the individual, between the 



