462 FATS. 



exert a feeble diastatic action. Diastatic ferment is found also in grain and 

 leguminous fruits, in hay and other vegetable foods. 



(6) Proteolytic ferments: In the gastric juice (pepsin), the muscles, also in 

 germinated seeds, for example vetches, malted barley, and in the myxomycetes; 

 in the pancreatic juice (trypsin), the intestinal juice, the urine. Pepsin and 

 trypsin diffuse through membranes like peptone. 



(c) Fat-splitting ferments: in the pancreatic juice. 



(d) Milk-coagulating -ferments: in the stomach, the pancreatic juice, the urine. 



NITROGENOUS GLUCOSIDS. 



The following nitrogenous glucosids, which on hydrolytic treatment take up 

 water and are decomposed into sugar and other atom-groups, may be considered 

 here: 



Cerebrin, C 57 H 110 N 2 O 25 . 



Protagon in the medullary substance of nerves (C 66 . 30 N 2 . 39 H 10 . 69 P 1 . 068 per cent.) 



Chitin, 2 (C 15 H 26 N 2 O 10 ) , a nitrogenous glucosid or amin of a carbohydrate in the 

 cutaneous covering of all arthropods, also in the intestine and the trachea of these 

 animals; soluble in concentrated hydrochloric or nitric acid. The hyalin of the 

 bladder-worms is closely allied to chitin. Among the glucosids of the vegetable 

 kingdom are also solanin, amygdalin and salicin. 



NITROGENOUS PIGMENTS. 



These are of unknown constitution and occur only in animals. In all proba- 

 bility they are all derivatives of hemoglobin. They are: (i) Hematin and hema- 

 toidin. (2) The biliary pigments. (3) The urinary pigments. (4) Melanin or 

 the black pigment contained partly in epithelial cells (choroid, iris, deep epidermal 

 cells in colored races) , partly in connective-tissue corpuscles (lamina fusca of the 

 choroid) , in hairs and in pathological neoplasms. Schmiedeberg produced melanin 

 by boiling albumin for a long time with concentrated mineral waters. The melanin 

 >repared from a melanosarcoma had the following composition: C 68 H 64 N 10 SO 26 + 



ORGANIC NON-NITROGENOUS ACIDS. 



The fatty acids, constructed according to the formula C n H 2n - 1 O(OH) f are 

 present in the body in part free, in part combined. In the free state the volatile 

 fatty acids are found in decomposing cutaneous secretions (sweat) , also in the 

 large intestine. In combination, acetic acid and caproic acid will appear as 

 amido-combinations in glycin (amido-acetic acid) and leucin (amido-caproic acid) . 

 Particularly, however, the fatty acids are combined with glycerin to form neutral 

 fats, from which, in the process of pancreatic digestion, the fatty acids are again 

 decomposed. 



The acids of the acrylic-acid series, constructed according to the formula 

 C n H 2 n- 3 (HO), yield the animal organism but one acid, namely oleic acid. This, 

 also, forms with glycerin the neutral fat, olein. It will be advisable at this 

 point to discuss the neutral fats, in the formation of which both the fatty acids 

 and oleic acid are utilized. 



THE FATS. 



The fats occur abundantly in the animal body, but probably also in all plants, 

 in the latter particularly in the seeds (nuts, almond, cocoanut, poppy), less 

 commonly in the pericarp (olive) , or in the root. They are obtained by expression, 

 by melting or by extraction with ether or boiling alcohol. They contain a smaller 

 amount of oxygen than the carbohydrates. On paper they produce characteristic 

 fat-spots; agitated with colloidal substances they yield an emulsion. If neutral 

 fats are superheated with water or are heated with certain ferments or are permitted 

 to undergo decomposition, they take up water and break up into glycerin and 

 free fatty acids, of which the latter, if volatile, diffuse a rancid odor. Treated 

 with caustic alkalies they likewise take up water and are decomposed into glycerin 

 and fatty acids. The fatty acids form salt-like combinations (soaps) with the 

 alkali, while the glycerin is set free. The soap-solutions in turn dissolve fats. 

 Glycerin, a triatomic alcohol, C 3 H 5 (OH) 3 , combines (i) with the following mono- 

 basic fatty acids: 



