viii] HEREDITY 113 



the alcoholism is not the result of nervous disorder, 

 which in the next generation appears as insanity ; 

 and in the second place, in order to prove a causal 

 connexion, in addition to this it must be shown that 

 insanity is actually more frequent in the descendants 

 of drunkards than in those of the sober. The un- 

 doubted evils of excessive drinking are many and 

 obvious enough, but it does not follow that physical 

 or mental degeneration of the descendants are among 

 them, and it may be a false hope to suppose that 

 these evils could be removed merely by the abolition 

 of drink. 



The same sort of argument may apply to the 

 undoubted physical and mental inferiority of our 

 slum population. It is not yet proved whether this 

 is the effect of miserable surroundings, or whether 

 the ' unfit ' gravitate to the worst places because the 

 more fit occupy the better. These are problems 

 which society has as yet scarcely attempted to face, 

 and yet it is clear that on their correct solution 

 depends the central question of social reform. If 

 man is to any appreciable extent the creature of his 

 environment, then improved conditions will improve 

 the race. But if, as the study of heredity suggests, 

 though it would be rash to say it is proved, man 

 is almost entirely the product of inborn factors 

 which are hardly affected by environment, then 

 improved conditions may only encourage the pro- 



