THE PRESENT EVOLUTION OF MAN — MENTAL 353 



very much less for them than races that have had 

 little or no experience of them. Between narcotics in 

 relation to which the individual is able with ease to 

 vary greatly — e. g. tobacco — and narcotics in relation to 

 which the individual is able to vary comparatively little 

 — e. g. alcohol — lie the other narcotics, some of which 

 resemble tobacco in the ease with which the individual 

 is able to undergo protective reaction against them, and 

 others alcohol in the absence of the power of making, 

 to any great extent, such protective reaction. As in 

 the case of diseases, the worst, the most death-dealing, 

 of narcotics are those against which the race is pro- 

 tected almost solely by the inborn power of making 

 immediate resistance ; a power which arises in the race 

 only through a very tedious process of evolution, the 

 result of a prolonged and stringent process of selection. 

 Except as regards alcohol and opium, we have little 

 or no evidence to assist us in forming an estimate of the 

 extent of the evolution caused in various races by the 

 use of deadly narcotics. We can estimate its extent in 

 different cases only by compai'ing races which have been 

 long and disastrously familiar with this or that nar- 

 cotic, with races which have had little or no experience 

 of them ; and save in the case of the two narcotics 

 named, I do not know that anything has been published 

 in which such comparisons are instituted — possibly for 

 the reason that no races previously unfamiliar with them 

 have recently acquired the habit of using them. I 

 confess, however, that I have not very diligently sought 

 evidence bearing on the matter, being convinced that it 

 is a foregone conclusion, that wherever any narcotic has 

 for a lengthened period been the cause of a considerable 

 elimination of the unfit in relation to it, it has also, like 

 virulent zymotic disease, like alcohol, like opium (as we 

 shall see), been the cause of a considerable evolution 



protective against itself. 



A A 



