ALBUMEN, AND CASEINE. 103 



compounds assume the same arrangement when acted on 

 by potash at a high temperature. 



All the organic nitrogenized constituents of the body, 

 how different soever they may be in composition, are 

 derived from proteine. They are formed from it, by 

 the addition or subtraction of the elements of water or 

 of oxygen, and by resolution into two or more com- 

 pounds. 



5. This proposition must be received as an undeniable 

 truth, when we reflect on the development of the young 

 animal in the egg of a fowl. The egg can be shown to 

 contain no other nitrogenized compound except albu- 

 men. The albumen of the yolk is identical with that 

 of the white ; (23) the yolk contains, besides, only a 

 yellow fat, in which cholesterine and iron may be de- 

 tected. Yet we see, in the process of incubation, 

 during which no food and no foreign matter, except the 

 oxygen of the air, is introduced, or can take part in the 

 development of the animal, that out of the albumen, 

 feathers, claws, globules of the blood, fibrine, mem- 

 brane and cellular tissue, arteries, and veins, are pro- 

 duced. The fat of the yolk may have contributed, 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 organized tissues in which vitality resides, 

 because the albumen of the white and of the yolk al- 

 ready contains, for the quantity of nitrogen present, ex- 

 actly the proportion of carbon required for the forma- 

 tion of these tissues. 



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



