NATURE OF FERMENT. 115 



gestion when taken into the stomach. The action of 

 the empyreumatic matters in coffee and tobacco-smoke, 

 of creosote, of mercurials, &c., &c., is, on this ac- 

 count, worthy of peculiar attention with reference to 

 dietetics. 



The identity in composition of the chief constituents 

 of blood, and of the nitrogenized constituents of vege- 

 table food, has certainly furnished, in an unexpected 

 manner, an explanation of the fact, that putrefying 

 blood, white of egg, flesh, and cheese produce the 

 same effects in a solution of sugar as yeast or ferment ; 

 that sugar, in contact with these substances, according 

 to the particular stage of decomposition in which the 

 putrefying matters may be, yields, at one time, alcohol 

 and carbonic acid ; at another, lactic acid, mannite, and 

 mucilage. The explanation is simply this, that ferment, 

 or yeast, is nothing but vegetable fibrine, albumen, or 

 caseine, in a state of decomposition, these substances 

 having the same composition with the constituents of 

 flesh, blood, or cheese. The putrefaction of these 

 animal matters is a process identical with the metamor- 

 phosis of the vegetable matters identical with them ; it 

 is a separation or splitting up into new and less complex 

 compounds. And if we consider the transformation of 

 the elements of the animal body (the waste of matter 

 in animals) as a chemical process, which goes on under 

 the influence of the vital force, then the putrefaction of 

 animal matters out of the body is a division into simpler 

 compounds, in which the vital force takes no share. 

 The action in both cases is the same, only the products 



