8 A STUDY IN HEREDITY 



case, mere variations of those two.^ Lamarck, 

 because he first formally enunciated it, gave his 

 name to the one theory ; Darwin, for the same 

 reason, gave his to the other. We have seen that 

 all men have, within limits, a belief in evolution. 

 It is curious that during every age they have 

 accepted as a belief the method of evolution laid 

 down by Lamarck, but have followed as a practice 

 that laid down by Darwin. In other words, they 

 have believed that races change in the manner 

 described by Lamarck, but have sought to improve 

 their own plants and animals in the manner 

 described by Darwin. 



The two theories can be explained best by 

 illustrations drawn from the animal world, but first 

 it is necessary to define two important terms. All 

 the characters of a living being, every physical 

 structure and every mental trait, may be placed in 

 one of two categories. Either they are inborn, or 

 they are acquired} An inborn or innate character 



1 Evolution must proceed by the transmission of inborn traits, or 

 of acquired traits, from parent to child, and by their accentuation 

 during succeeding generations. Even if we regard the course of 

 evolution as designed and predestined, no other method is thinkable, 

 because no traits other than the inborn and the acquired exist in 

 living beings. 



2 It should be observed that the word "acquired" is a technical 

 biological term, which has a very precise and restricted meaning. It 

 can be applied only to individuals as such, never to races or species 

 as such. Thus, if it were stated that, during its evolution, the negro 

 race acquired woolly hair, the term would not be used in its strict 



