g] VITAL IMPORTANCE TO MANKIND 267 



under drugs, and constituting important relievers of pain. The 

 eating or smoking of opium, which at first produces alluring dreams 

 and pleasurable visions, may become an uncontrollable addiction 

 leading to delirium and death. The chewing of the leaves of the 

 Coca shrub, containing cocaine, gives resistance to fatigue and 

 hunger and at the same time a feeling of exaltation; but if habitual, 

 it may in time lead to severe physical deterioration and even death. 

 Other important narcotics are cannabis, obtained from the Hemp 

 plant and widely used in medicine to relieve pain as well as in the 

 treatment of nervous disorders ; fly agaric, obtained from the 

 poisonous Fungus of that name, which when chewed or added to 

 beverages has an intoxicating effect involving hallucinations and 

 finally unconsciousness ; peyote (mescal buttons), from an American 

 Cactus, mostly chewed for the feeling it produces of well-being 

 accompanied by hypnotic trances ; products from Thorn-apples and 

 Henbane, which when smoked or eaten produce excitations, illusions, 

 and sometimes fanatical acts ; and the Oceanian kavakava, whose 

 use as a beverage has a sedative and soporific action, bringing about 

 pleasant sensations. Cannabis consumption as hashish, marijuana, 

 etc., causes states of ecstasy and stupefaction and may have serious 

 results, as when it leads to fanatical acts by addicts. 



Structural and Sheltering Materials 



It can scarcely be questioned that wood is nowadays, and from 

 before the dawn of history has been, the most generally important 

 of all structural materials. Its uses in the construction of human 

 habitations and shelters, furniture and utensils, vehicles and boats, 

 tools and all manner of fittings and fencings, etc., are too universally 

 familiar to require detailed enumeration. If we reflect that until 

 a century ago ships were made almost entirely of wood, without 

 which the exploration and colonization and general development of 

 most of the world would accordingly have been impossible, we have 

 one impressive indication of its immense significance in human 

 affairs ; and to this day wood is the most widely used commodity, 

 apart from foodstuffs and, perhaps, clothing materials. It is also 

 highly versatile as a raw material (and one of the few that can per- 

 petually be renewed) for conversion into products as varied as paper 

 and textiles, s'oap and lubricants, stock-feed and motor fuel, plastics and 

 disinfectants, explosives and preservatives (to mention only a few). 



Quite apart from questions introduced by their local availability. 



