NON-NITROGENIZED ALIMENTARY SUBSTANCES. 



173 



and leaves. Both gums and mucilages mix readily with water, giving it a 

 consistence called mucilaginous. The composition of gum is C 20 Hi 10 . 

 Experiments have shown that gum passes unchanged through the alimentary 

 canal and has no nutritive properties. Gum is mentioned in this con- 

 nection from the fact that it is frequently used in the treatment of disease 

 and is thought by many to be nutritious. 



The carbohydrates, although important articles of food and especially use- 

 ful in the processes involved in the production of animal heat, are not in 

 themselves capable of sustaining life. 



Fats. Fatty matters, derived from both the animal and the vegetable 

 kingdoms, are important articles of food. As a constituent of the organism, 

 fat is found in all parts of the body, 

 with the exception of the bones, teeth 

 and fibrous tissues. It necessarily con- 

 stitutes an important part of all animal 

 food and is taken in the form of adipose 

 tissue, infiltrated in the various tissues 

 in the form of globules and granules of 

 oil, and in suspension in the caseine and 

 water in milk. Animal fat is a mixture 

 of oleine, palmitine and stearine, in va- 

 rious proportions, and possesses a con- 

 sistence which depends upon the relative 

 quantities of these substances. 



The different varieties of animal fats 

 do not demand special consideration as 

 articles of diet. Butter, an important 

 article of food, is somewhat different from the fat extracted from adipose 

 tissue, but most varieties of fat lose their individual peculiarities in the pro- 

 cess of digestion and are apparently 

 identical when they find their way into 

 the lacteal vessels. 



In the vegetable kingdom, fat is 

 particularly abundant in seeds and 

 grains, but it exists in quantity in some 

 fruits, as in the olive. Here it is gen- 

 erally called oil. It exists in consider- 

 able proportion in nuts and in certain 

 quantity in the cereals, particularly In- 

 dian corn. 



Fat, both animal and vegetable, 

 may be either liquid or solid. It has a 

 peculiar oily feel, a neutral reaction, 

 and is insoluble in water and soluble in 

 alcohol particularly hot alcohol chlo- 

 roform, ether, benzine and solutions of soaps. The solid varieties are exceed- 

 13 



FIG. 50. Crystals of palmitine and palmitic 

 acid (Funke). a, a, a, palmitine ; b, pal- 

 mitic acid. 



FIG. HI. Crystals of stearine and stearic. acid 

 (Funke). a, a, a, stearine ; 6, stearic acid. 



