CHAPTER IV 



Opium and other narcotics. — After having devoted so 

 much space to alcohol, it is not necessary to dwell at 

 length on the other narcotics, the use of which has 

 resulted in mental evolution ; that is, which have been 

 sufficiently poisonous and prevalent to have caused a 

 considerable elimination of the unfit in relation to them, 

 in this resembling prevalent and deadly diseases — e.g. 

 malaria and tuberculosis, — and differing from diseases 

 which though deadly are not prevalent — e. g. rabies, — 

 and diseases which though prevalent are not deadly 

 — e. g, chicken-pox ; which last diseases, in the absence 

 of any appreciable evolution caused by them, are resem- 

 bled by such prevalent but comparatively innocuous 

 narcotics as tobacco. The evolution against the other 

 deadly and prevalent narcotics must have proceeded on 

 much the same lines as that against alcohol, and 

 against deadly and prevalent forms of zymotic disease. 

 The gradual improvements in the manufacture of such 

 narcotics — i. e. the gradual increase in the poisonous 

 nature of the preparations of them manufactured by 

 races that had discovered their use — must have been 

 accompanied, as in the case of alcohol, by a protective 

 evolution whereby, through survival of the fittest, the 

 craving grew less. Doubtless, however, since the manu- 

 facture of strong — i. e. poisonous — preparations of some 



of them is much easier, aad less complicated than the 



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