108 DIGESTION COMPARED 



membrane and cellular tissue, arteries and veins, 

 are produced. The fat of the yolk may have con- 

 tributed, to a certain extent, to the formation of 

 the nerves and brain ; but the carbon of this fat 

 cannot have been employed to produce the organ- 

 ised tissues in which vitality resides, because the 

 albumen of the white and of the yolk already con- 

 tains, for the quantity of nitrogen present, exactly 

 the proportion of carbon required for the formation 

 of these tissues. 



6. The true starting-point for all the tissues is, 

 consequently, albumen ; all nitrogenised articles of 

 food, whether derived from the animal or from the 

 vegetable kingdom, are converted into albumen 

 before they can take part in the process of nutri- 

 tion. 



All the food consumed by an animal becomes in 

 the stomach soluble, and capable of entering into 

 the circulation. In the process by which this solu- 

 tion is effected, only one fluid, besides the oxygen 

 of the air, takes a part ; it is that which is secreted 

 by the lining membrane of the stomach. 



The most decisive experiments of physiologists 

 have shewn that the process of chymificatioii is 

 independent of the vital force ; that it takes place 

 in virtue of a purely chemical action, exactly simi- 

 lar to those processes of decomposition or transfor- 

 mation which are known as putrefaction, fermenta- 

 tion, or decay (eremacausis). 



7. When expressed in the simplest form, fer- 



