NARCOTICS 207 



is avoided. By a single process of evolution provision has 

 been made against many maladies. The most death-dealing 

 diseases are those against which immunity cannot be 

 acquired, or can be acquired only slowly and with difficulty 

 (e. g. malaria). Alcohol resembles tuberculosis in that little 

 immunity can be acquired against it by the individual. 

 Without very greatly increasing the dose, the drinker is able 

 to reproduce the immediately poisonous effects (intoxication) 

 which he felt on the first occasion of using the poison. It is 

 just these poisonous effects that he seeks to renew. The 

 mortality caused by alcohol in a race new to it is very great, 

 and tends to produce inborn immunity that is, to evolve a 

 race which does not desire the immediately poisonous effects, 

 and which, therefore, drinks in moderation. Against tobacco 

 complete immunity may be acquired. Nicotine is very- 

 poisonous to the beginner, but not only does the habitual 

 smoker acquire the power of tolerating immensely increased 

 doses, but he never craves to renew the immediately 

 poisonous effects which he felt when he first used the poison. 

 In other words all smokers smoke in " moderation " ; that is, 

 they do not seek to intoxicate, to immediately poison them- 

 selves with nicotine. The mortality caused by tobacco is so 

 small as to be negligible. As a consequence and in this it 

 resembles chicken-pox no evolution results from racial 

 experience of it. Races who have long used it desire it in 

 quantities as large as races that have had no previous 

 experience of it. Opium lies midway between alcohol and 

 tobacco. Immensely increased doses can be tolerated by the 

 habitual user, but, if he belong to a race which has had no 

 previous experience of opium, he generally desires to repro- 

 duce the intoxication he felt on the first occasion of using 

 it. Opium, like measles, is therefore the cause of a large 

 mortality. The resulting evolution tends to render the race 

 "immune," so that it no longer desires opium in such 

 quantities as to produce intoxication. It would appear, 

 therefore, that the power of tolerating increased quantities 

 is a great advantage. The race does not start from the 

 scratch. It evolves immunity much more quickly and 

 easily than in the case of alcohol. After an experience of a 

 few hundred years the natives of India appear quite " im- 

 mune." After two centuries the Chinese have evolved far 

 towards immunity. But a disastrous experience of thousands 

 of years has not rendered North Europeans fully " immune " 

 to alcohol. 



353. If this parallel between diseases and narcotics holds 



