AND PHYSIOLOGY. 



177 



coagulated or made hard and white by heat or mixture with 

 Nitric Acid. In some parts of vegetables also, especially in 

 the seeds and fruit, is found a substance which, from its re- 

 semblance to animal albumen, is called vegetable albumen. 

 Fibrine exists in the blood and muscles of animals, forming 

 the coagulum or clot of blood, and the proper muscular sub- 

 stance! There is also a corresponding substance in plants 

 known as vegetable Fibrine. Casein closely resembles Albu- 

 men in its constitution, but differs in many of its physical 

 properties. For while Albumen is coagulated by heat, Casein 

 is only coagulated by lactic and acetic acids. Casein is best 

 seen in cheese. These three substances are the essential ele- 

 ments of nutrition in mammals, and though every other prin- 

 ciple may be supplied in the food, yet the body is insufficiently 

 nourished without Albumen and Fibrine. Gelatin, which 

 exists abundantly in the cartilage of animals, is another 

 azotised principle of food. This, however, of itself can not 

 support life, although it can be changed into albumen, or 

 some of its compounds by the action of the fluids of the 

 stomach. 



322. Non -azotised Constituents. — Of the non-azotised 

 constituents of food, the Saccharine and Farinaceous and 

 Oily, are the principal ones, although there are many others 

 of less importance. Of the former, the principal element is 

 starch, while the sugar is secondary or subsidiary to it, and 

 in the latter we find an abundance of a Hydro- Carbon, or a 

 compound of Hydrogen, Carbon, and Oxygen, and all are 

 essential elements in combustion. 



323. Is an exclusively Animal or Vegetable Diet the 

 best adapted to Man? Testimony of Experience. Ex- 

 perience of Dr. Kane.— The question then which naturally 

 suggests itself here is, whether man is adapted to live ex- 



What effect has heat and Nitric Acid upon Albumen ? Where is Fibrine found ? How 

 does Casein differ from Albumen? Will Oelatin (or Jelly) of itself support life ? 322. 

 What are examples of non -azotised kinds of food? 323. Is man made to live on an ex- 

 clusively vegetable or animal diet ? 



