144 WHAT DOES MAN LIVE UPON? 



trary to all expectation, and has only still more entangled 

 the problem. Oudry found in Tea a substance crystal- 

 lizing in delicate white needles, which he called Theine, 

 and the quantity of which amounted to about ^ per cent. 

 Even earlier, in 1820, Runge had detected in Coffee, a 

 substance in fine crystals, with a silky lustre, of which there 

 was scarcely ^ per cent. Runge named it Caffeine. 

 Another inquirer found in Cacao, Theobromine in smaller 

 quantity ; then theine was shown to exist in Mate, caffeine 

 in Guarana ; and finally, more accurate researches demon- 

 strated that theine and caffeine are one and the same 

 substance, which is distinguished from all other known 

 vegetable substances by the extraordinarily large proportion 

 of nitrogen it contains, and that theobromine if not iden- 

 tical, is most intimately related to it. Is it not in the 

 highest degree remarkable, that a proportion, even though 

 only very small, of one and the same peculiar substance, 

 occurs in all these beverages, which have with such striking 

 rapidity become necessaries of life over the whole inhabited 

 globe ? A remarkable problem, from the solution of which 

 we are still so far the more distant, that the experiments 

 hitherto instituted by physicians and chemists, have as yet 

 furnished no evidence of a special action resulting from the 

 administration of large quantities of pure theine ; the 

 substance, therefore, appears devoid of any striking action 

 on the animal economy. 



I return from this digression, which, however, is not 

 altogether foreign to the main question, to my peculiar 

 subject. Man requires for his nutrition three principal 

 substances, rich in nitrogen, fibrine, caseine, and albumen ; 

 and these occur not only in the animal kingdom, but are 

 generally distributed in the vegetable world. Further, for 

 the maintenance of respiration, and therefore of heat, he 



