24 HEREDITY AND INHERITANCE 



A consideration of these denials, which have ceased to appeal 

 to many, may be of use as affording opportunity for emphasising 

 two facts. 



I. Reappearance of a character from generation to generation 

 does not of itself prove the inheritance of that character, if it 

 be originally interpretable as the result of nurture (influences 

 of activity and surroundings operative on the body), and if 

 there be from generation to generation a persistence of the 

 conditions which were originally instrumental in evoking the 

 character. It is plain that the reappearance may be the result 

 of similar effects hammered on each successive generation. 



Alpine plants brought to a lowland garden have been known 

 to become much changed, and their descendants likewise. But 

 there is good reason to believe, as we shall afterwards see, that 

 the novel conditions directly impressed their effects on each 

 successive crop. 



What impressed Buckle was the power of the environment 

 in the widest sense ; it holds the organism in its grip, and hammers 

 it into shape. This no one will gainsay, but we know that 

 similar nurture has different results on different natures ; the 

 duckling is not known to be less a duckling because hatched 

 and brought up by a hen. Moreover, we know of the reappear- 

 ance from generation to generation of many characteristics 

 which cannot be interpreted as due to nurture — which often 

 emerge, indeed, in the very teeth of nurture. 



At the same time, it is of great importance to bear in mind that 

 an organism cannot be separated from its environment except at 

 the risk of some fallacy. We may say that along with the organic 

 heritage contained in the germ-cells every organism has what 

 may be called an external heritage of appropriate environmental 

 influences, which supply the stimuli for normal development. 



Appropriate food is part of the normal environment, and the 

 supply of oxygen and water may be grouped in the same set ; other 

 factors, like the osmotic pressure or the presence of calcium salts in 



