PART II. 



ANIMAL PHYSIOLOGY. 



LESSOR XXI. 



THE OKIGINAL COMPOUNDS OF THE ANIMAL BODY. 



347. THE egg of an viperous (egg-laying) animal, is found to 

 consist of two parts the yelk, and the white, as it is called. The 

 yelk is incapable of forming a tissue, and is destined to be entirely 

 converted, by the process of incubation, into cells. The white is 

 known to chemists by another name, that of albumen, and this is 

 found to be the most universal and important constituent of organ- 

 ized beings. 



348. Albumen, through the aid of a series of chemical and vital 

 processes, becomes nerve, muscle, tendon, ligament, membrane, 

 areolar tissue, horny substance, feathers, the animal portion of 

 bone, $c. 



349. These remarkable changes are not confined to the embryo, 

 or the young condition of an animal, for, on the contrary, they are 

 constantly taking place through all the phases of adult life. By the 

 wonderful chemistry of digestion, all substances of similar compo- 

 sition are reduced to albumen, which forms an essential part of the 

 fluids absorbed for the nourishment of the tissues. 



350. When Gelatine (calves-foot jelly) is consumed as food, there 

 is little doubt that it becomes associated with the general circulation, 

 but the doctrine of Chemical affinity appears to prevail in the organ- 

 ization of tissues like joins like so that on this principle the 

 gelatine goes to where it belongs to the gelatinous tissues the 

 bones and teeth. 



