VEGETABLE PRODUCTS: CAFFEINE. 179 



of certain roasted seeds (coffee). Some cause there 

 must be, which would explain how the practice has 

 become a necessary of life to whole nations. But 

 it is surely still more remarkable, that the beneficial 

 eifects of both plants on the health must be ascribed 

 to one and the same substance, the presence of 

 which in two vegetables, belonging to different 

 natural families, and the produce of different quar- 

 ters of the globe, could hardly have presented itself 

 to the boldest imagination. Yet recelit researches 

 have shewn, in such a manner as to exclude all 

 doubt, that caffeine, the peculiar principle of coffee, 

 and theine, that of tea, are, in all respects, identical. 



It is not less worthy of notice, that the American 

 Indian, living entirely on flesh, discovered for him- 

 self, in tobacco smoke, a means of retarding the 

 change of matter in the tissues of his body, and 

 thereby of making hunger more endurable ; and 

 that he cannot withstand the action of brandv, 

 which, acting as an element of respiration, puts 

 a stop to the change of matter by performing the 

 function which properly belongs to the products of 

 the metamorphosed tissues. Tea and coffee were 

 originally met with among nations whose diet is 

 chiefly vegetable. 



87. Without entering minutely into the medi- 

 cinal action of caffeine (theine), it will surely appear 

 a most striking fact, even if we were to deny its 

 influence on the process of secretion, that this sub- 

 stance, with the addition of oxygen and the elements 



N 2 



