148 ANATOMY FOR NURSES. [CHAP. XIII. 



Fats. Fats are composed of carbon, hydrogen, and oxygen. 

 They contain on an average in every 100 parts : 



Carbon 76.5 parts 



Hydrogen 12 " 



Oxygen 11.5 " 



The most important fats are stearin, palmatin, margarin, and 

 olein, which exist in varying proportions in the fat of animals 

 and vegetable oils, and in milk, butter, lard, etc. The brains of 

 animals and the yolk of eggs contain a complex phosphorized 

 fat, called lecithin. Fatty matters are very abundant in olives, 

 sweet almonds, chocolate, castor-oil bean, hemp, and flaxseed. 

 Most of the fatty substances of food are liquefied at the tem- 

 perature of the body, and are readily oxidized, probably on 

 account of the large amount of carbon which they contain. 



Carbo-hydrates. In the carbo-hydrates there is sufficient 

 oxygen present to saturate all the hydrogen and to form water; 

 hence their name. In the fats, there is not quite so much 

 oxygeA as hydrogen ; water is, therefore, not formed in them, 

 and in this particular they differ from the carbo-hydrates. 



The carbo-hydrates contain in every 100 parts about : 

 . 



Carbon 44 parts 



Hydrogen ." \ ' . . . 6 ""* 



Oxygen 50 " 



The principal carbo-hydrates are starch and sugars. Starch is 

 found in wheat, Indian corn, oats, and all grains, in potatoes, 

 peas, beans, roots and stems of many plants, and in some fruits. 

 In a pure state, it appears as a white powder, as in arrowroot 

 and cornstarch. Under the influence of dry heat, starch may 

 be converted into a soluble substance, called dextrine; and, 

 under the action of certain of the digestive juices, at the tem- 

 perature of the body, into sugar. Of sugars there are several 

 kinds : cane sugar or sucrose, obtained chiefly from the sugar 

 cane, beet sugar, and maple sugar; grape sugar or glucose, found 

 in grapes, peaches, and other fruits (it is also readily manufact- 

 ured from starch) ; milk sugar or lactose, obtained from milk. 



Carbo-hydrates are readily oxidized ; together with fats, they 

 are often classed as " non-nitrogenous " food-stuffs. 



Water is a compound of oxygen and hydrogen, water being 



