FIBRINE AND ALBUMEN. 43 



ble of producing an elementary body, such as carbon or 

 nitrogen, out of substances which do not contain it ; 

 and it obviously follows, that all kinds of food fit for 

 the production either of blood, or of cellular tissue, 

 membranes, skin, hair, muscular fibre, &c., must con- 

 tain a certain amount of nitrogen, because that element 

 is essential to the composition of the above-named 

 organs ; because the organs cannot create it from the 

 other elements presented to them ; and, finally, because 

 no nitrogen is absorbed from the atmosphere in the vital 

 process. 



The substance of the brain and nerves contains a 

 large quantity of albumen, and, in addition to this, two 

 peculiar fatty acids, distinguished from other fats by 

 containing phosphorus (phosphoric acid?). One of 

 these contains nitrogen (Fremy) . 



Finally, water and common fat are those ingredients 

 of the body which are destitute of nitrogen. Both are 

 amorphous or unorganized, and only so far take part in 

 the vital process as that their presence is required for 

 the due performance of the vital functions. The inor- 

 ganic constituents of the body are, iron, lime, magnesia, 

 common salt, and the alkalies. 



IX. The nutritive process in the carnivora is seen in 

 its simplest form. This class of animals lives on the 

 blood and flesh of the graminivora ; but this blood and 

 flesh is, in all its properties, identical with their own. 

 Neither chemical nor physiological differences can be 

 discovered. 



