46 ALBUMEN, AND CASEINE. 



that it is insoluble in water ; although we cannot doubt 

 that it was originally dissolved in the vegetable juice, 

 from which it afterwards separated, exactly as fibrine 

 does from blood. 



The second nitrogenized compound remains dissolved 

 in the juice after the separation of the fibrine. It does 

 not separate from the juice at the ordinary temperature, 

 but is instantly coagulated when the liquid containing it 

 is heated to the boiling point. 



When the clarified juice of nutritious vegetables, 

 such as cauliflower, asparagus, mangel-wurtzel, or tur- 

 nips, is made to boil, a coagulum is formed, which it is 

 absolutely impossible to distinguish from the substance 

 which separates as a coagulum, when the serum of blood 

 or the white of an egg, diluted with water, are heated 

 to the boiling point. This is vegetable albumen. It is 

 found in the greatest abundance in certain seeds, in nuts, 

 almonds, and others, in which the starch of the gra- 

 mineae is replaced by oil. 



The third nitrogenized constituent of the vegetable 

 food of animals is vegetable caseine. It is chiefly found 

 in the seeds of pease, beans, lentils, and similar legu- 

 minous seeds. Like vegetable albumen, it is soluble in 

 water, but differs from it in this, that its solution is not 

 coagulated by heat. When the solution is heated or 

 evaporated, a skin forms on its surface, and the addition 

 of an acid causes a coagulum, just as in animal milk. 



These three nitrogenized compounds, vegetable fi- 

 brine, albumen, and caseine, are the true nitrogenized 

 constituents of the food of graminivorous animals ; all 



