2 TOBACCO : ITS HISTORY. 



tion in the use of alcoholic liquors in the animal 

 system, perhaps the time will come when the 

 use of narcotics also will he rationally explained. 

 The substances which are adapted to the forma- 

 tion of blood renew the organised tissues of the 

 body ; whilst another class of substances, in the 

 normal state of health, serve to support the pro- 

 cess of respiration. " Tlie former may be called 

 the plastic elements of nutrition; the latter, 

 elements of respiration^ Amongst the latter 

 Liebig classes zt-z/ze, heer, and spirits. "In all 

 chronic diseases death is produced by the chemical 

 action of the atmosphere. When those substances 

 are wanting whose function in the organism is 

 to support the process of respiration — namely, 

 fat, starch, gum, sugar of all kinds, wine, beer, 

 spirits ; — when the diseased organs are incapable 

 of performing their proper function o^ producing 

 these substances ; — when they have lost the power 

 of transforming the food into that shape in which 

 it may, by entering into combination with the 

 oxygen of the air, protect the system from its in- 

 fluence —then the substance of the organs them- 

 selves, the fat of the body, the substance of the 



