g] VITAL IMPORTANCE TO MANKIND 263 



them of special substances having a particular physiological action 

 on the human body : commonly such substances are alkaloids, some 

 of which are powerful poisons if administered unwisely, while others 

 are dangerously habit-forming. Yet in small quantities skilfully 

 administered, even the most poisonous or dangerous drugs can be 

 of value to human health and well-being. 



Throughout the world there are used for medicinal purposes some 

 thousands of different plants or plant products — many of them only 

 locally by savage peoples. The use of others has been rendered 

 obsolete by synthesis of their active principles. Some are widely 

 cultivated, but many more are gathered chiefly or entirely in the 

 wild state and are still important commercially. A few of the most 

 significant, classified according to the part of the plant from which 

 they come, are the following: 



Obtained from fruits and seeds : chaulmoogra oil, from a south- 

 east Asian tree, containing principles effective in the treatment of 

 leprosy ; colocynth, from a widespread perennial vine now cultivated 

 in the Mediterranean region, serving as a powerful purgative, as 

 does also croton oil, obtained from a shrub or small tree of south- 

 eastern Asia ; nux vomica, obtained from a tree ranging from India 

 to Australia, used as a stimulant in small quantities as it contains 

 strychnine ; strychnine itself, obtained from the same and allied 

 plants ; opium, obtained as an exudation from the injured fruits of 

 the widely cultivated Opium Poppy, employed to relieve pain but 

 flagrantly misused as a narcotic in the Orient ; psyllium, from 

 Plantains, used chiefly as a laxative ; strophanthus, from two 

 African lianes, used as a heart stimulant ; and wormseed, a native 

 of the warm parts of the New World, used in the treatment of 

 hookworm infections. 



From flowers are obtained chamomile, which is rather widely 

 cultivated and used for a variety of purposes ; hops, extensively 

 cultivated in temperate regions and used for their sedative and tonic 

 properties as well as in brewing ; and santonin, one of the best 

 remedies for intestinal worms. 



The vegetative parts of plants contribute numerous drugs. From 

 leaves are derived, for example, aloe, from African and American 

 Aloes, used as purgatives ; belladonna, from the Deadly Nightshade 

 of Europe, etc., but now extensively cultivated, used for the local 

 relief of pain and for a variety of other commendable purposes ; 

 cocaine, from the leaves of the South American Coca shrub that is 

 now extensivelv cultivated in the tropics, used chiefly as a local 



