CHAP. I.] IMPORTANCE OF A MIXED DIET. 43 



dry assumes the appearance of glue. It differs from gelatine, in not 

 being precipitated by tannin, and in yielding precipitates to acetic 

 acid, alum, acetate of lead, and the protosulphate of iron, which 

 do not disturb a solution of gelatine. It resembles the proteine 

 compounds in containing a minute quantity of sulphur. 

 Mulder' s analysis of one hundred parts is, 



Nitrogen .... 14*44 



Carbon .... 49-96 



Hydrogen .... 6'63 



Oxygen .... 28-59 



Sulphur 0-38 



100-00 



Respecting the remaining substances included in the list of true 

 proximate principles, very few words are necessary, as they will be 

 more fully treated of in subsequent chapters. 



Elaine, Slearine, and Margarine are proximate principles of fat, 

 and are found also in the brain and nerves. Stearine exists but 

 sparingly, or not at all, in human fat. 



Hamatosine and Globuline are the constituents of the particles, 

 or corpuscles, to which the blood owes its colour. They are both 

 nearly allied to albumen ; and the latter is regarded as a compound 

 of proteine. 



The proximate principles which have been described in the pre- 

 ceding paragraphs are constituents of the animal food, upon which 

 the human race, and the inferior creatures, to a great extent sub- 

 sist ; and the discovery that similar principles exist in the vege- 

 table kingdom, also adapted for food, is of the highest interest, 

 as proving that both kingdoms of organized nature are capable 

 of affording the materials which are suited to supply the waste 

 in the animal tissues which is the necessary result of their vital 

 actions. The blood is the immediate pabulum of the tissues ; its 

 composition is nearly or entirely identical with them ; it is, indeed, 

 as Bordeu long ago expressed it, liquid flesh ; it contains the ele- 

 ments of the solids in a state of solution le sang est de la chair 

 coulante. The proteine compounds more immediately contribute 

 to the formation of the blood, and, as we have seen, may be 

 obtained directly from that fluid; and the process of nutrition 

 consists in the attraction of certain of these principles from the 

 blood, and the appropriation of them by the textures and organs, 

 in a form assimilated to that of their elementary parts. 



