I30 A STUDY IN HEREDITY 



of considerable evolution. It occupies a position 

 midway between tobacco and alcohol. The pro- 

 tective reaction whereby increased doses can be 

 tolerated, provides a short cut towards immunity. 

 This short cut is not so complete as in the case of 

 tobacco ; but, since it exists, the evolution is less 

 prolonged and tedious than that against alcohol. 

 For thousands of years many races have been 

 afflicted by alcohol, and their evolution is not yet 

 complete. The natives of India have used opium 

 for a few hundred years only, and their evolution 

 already appears complete. 



There is, besides, this further difference between 

 alcohol and opium. In the beginning alcohol was 

 manufactured in solutions so dilute as scarcely to 

 be poisonous ; but the manufacture of opium is 

 so easy that from the beginning it must have 

 been made of very poisonous strength. From the 

 first, therefore, opium selection must have been 

 very rapid and stringent. Races which have no 

 previous experience of alcohol become extinct when 

 introduced to strong modern solutions of it. The 

 fact that the races which use opium have undergone 

 evolution, not extinction, therefore proves the far 

 greater ease of the evolution against it. 



The Greeks of the time of Hippocrates were 

 acquainted with the medicinal use of opium,^ and 



* " First Report, Royal Commission on Opium," p. 147. 



