16 HUMAN PHYSIOLOGY. 



b. Alkali Albumin, found in the intestine during pancreatic digestion, 

 the result of the action, of alkalies upon the albumin of the food. 



c. Casein, the chief proteid of milk ; it is precipitated by acetic acid 

 and rennet. 



4. PEPTONES. These bodies are formed in the stomach and intestinal 

 tract by the action of the gastric and pancreatic juices upon the albumins 

 of the food. They are very soluble in water, alkaline and acid solutions ; 

 non-coagulable by heat; very diffusible. They are precipitated by tannic 

 acid and alcohol. 



5. ALBUMINOIDS. The albuminoids are the results of various modifica- 

 tions of albumins occurring during the nutritive process, as well as by 

 the action of various external influences. 



a. Mucin, the characteristic ingredient of mucus secreted by the 

 mucous membranes, giving to it its viscidity. 



b. Chondrin, found in cartilage. 



c. Gelatin, found in connective tissue, tendons, ligaments, bones, etc. 



d. Elastin, found in elastic tissue. 



e. Keratin, found in skin and epidermic appendages, nails, hair, horn, etc. 



6. FIBRIN. A filamentous albumin obtained by washing blood clots. It 

 is insoluble in water and mineral acids. 



As the properties of the compounds formed by the union of elements are 

 the resultants of the properties of the elements themselves, it follows that 

 the ternary substances, sugars, starches and fats, possess a great inertia and 

 a notable instability ; while in the more complex albuminous compounds, 

 in which sulphur and phosphorus are united to the four chief elements, 

 molecular mobility, resulting in isomerism, exists in a high degree. As 

 these compounds are unstable, of a greater molecular mobility, they are well 

 fitted to take part in the composition of organic bodies, in which there is 

 a continual movement of composition and decomposition. 



IV. PRINCIPLES OF WASTE. 



Urea. Xanthin, Sodium, "1 



Creatin, Tyrosin, Potassium, I Urates 



Creatinin, Hippuric Acid, Ammonium, 



Cholesterin, Calcium Oxalate, Calcium, 



These principles which represent waste are of organic origin, arising 

 within the body as products of disassimilation or retrograde metamorphosis 

 of the tissues; they are absorbed by the blood, carried to the various 

 excretory organs, and by them eliminated from the body. 



The excrementitious substances will be fully considered under excretion. 



