368 THE PRESENT EVOLUTION OF MAN— MENTAL 



for the people of Southern Asia, whilst, similarly taken, 

 it may be good for Europeans. However this may be, 

 Burmah is not India, and it is not reasonable to apply 

 to India conclusions based upon observations made in a 

 totally different country. It appears to me as regards 

 India, properly so called, there is no evidence whatever 

 to show that in any part of the country the consump- 

 tion of opium is anywhere a common and crying evil. 

 Of course I admit that the use of opium may be 

 abused, but I entirely disbelieve that this occurs to any 

 general or dangerous extent." — Ihid. pp. 66-7. 



A posteriori considerations therefore abundantly 

 confirm the conclusion we came to on db priori grounds ; 

 namely, that wherever the death-dealing narcotic opium 

 is in common use as an intoxicant, there it must be a 

 cause of evolution also. 



Evolution against any one zymotic disease is not pro- 

 tective to any extent against other zymotic diseases. It 

 would be interesting to know whether the same law 

 obtains as regards evolution against the various deadly 

 narcotics : for instance, it would be interesting to know 

 whether evolution against alcohol is, or is not, protective 

 against opium. Are the weak against alcohol, they 

 who crave greatly for it, the weak against opium also ? 

 Or is the one craving a thing distinct and separate 

 from the other ? It is very rare for both cravings to be 

 manifested in the same person ; indeed I do not re- 

 member to have heard of a case where this occurred to 

 any extent ; but, on the other hand, the cravings for 

 alcohol and tobacco very often co-exist. It seems 

 probable, therefore, that the cravings for those states 

 of mind that alcohol and opium (and other narcotics) 

 severally induce are distinct and separate, just as the 

 weaknesses against separate zymotic diseases are 

 distinct and separate, and therefore it seems probable 



