158 HEREDITARY CHARACTERS 



are partially or wholly immune to the malarial parasite. 

 But this is not what happens. . . . The heritable immunity 

 against these diseases occurs nowhere except among races 

 that have been exposed to their ravages ; and yet if acquired 

 qualities are not inherited, the existence of the disease in 

 their environment has no effect whatever in producing this 

 immunity. Such reasoning would not be admitted in any 

 other science." 1 



To those who understand the theory of natural selection, 

 nothing could be more grotesque than this interpretation of 

 it. Variations towards immunity to malaria certainly do 

 occur among races that are never subjected to it, as is 

 shown by the varying susceptibility of Englishmen living 

 in a country where the disease is prevalent, but no race 

 could acquire immunity without selection. The immunity 

 of the race is entirely due to the presence of the disease 

 in the environment. In so far as the development of the 

 new racial character immunity to malaria is concerned, 

 there is no " chance," blind or otherwise, about it. With 

 regard to the individual the question is whether he has 

 varied in the right or in the wrong direction. The man 

 who has varied towards immunity transmits his variation 

 with new variations. Some of his children will vary to- 

 wards greater immunity, and so on in each generation. The 

 individuals that vary in the wrong direction, that is, to- 

 wards being out of harmony with their environment, are 

 eliminated. Natural selection of inborn variations is a 

 question of adaptation to environment. The conclusion 

 that follows the extracts quoted above is this: "When I 

 am confronted with these difficulties in the way of accept- 

 ing the non-transmission of acquired qualities, I find it as 

 easy to believe that gloves were made without reference to 

 hands ; that carts were made without reference to horses ; 

 that keys were made without taking locks into considera- 

 tion ; that, when we find a seal and its impression in wax 

 side by side, we must suppose that the impression came into 



1 Mercier, Charles, op. cit. 



