176 ALIMENTATION. 



deprived entirely of food and drink. This fact it is important to bear in mind in con- 

 nection with observations on the nutritive value of different articles of food. 



Alimentation. 



Under the name of aliment, in its widest signification, it'Ms proposed to include all 

 articles composed of or containing elements in a form which enables them to be used 

 for the nourishment of the body, either by being themselves appropriated by the or- 

 ganism, by influencing favorably the process of nutrition, or by retarding disassimila- 

 tion. Those principles which are themselves appropriated may be called direct aliments ; 

 and those which simply assist nutrition without contributing reparative material, 

 together with those which retard disassimilation, may be termed accessory aliments. 

 By this definition of aliment, nothing is excluded which contributes to nutrition. The 

 air must be considered in this light, as well as water and all articles which are com- 

 monly called drinks. 



In the various articles used as food, nutritious elements are frequently combined with 

 each other and with indigestible and non-nutritious matters. The elements of the 

 food which are directly used in nutrition are the true alimentary principles, embracing, 

 thus, only those principles which are capable of absorption and assimilation. The 

 ordinary food of the warm-blooded animals contains alimentary principles united with 

 innutritious substances from which they are separated in digestion. This necessitates a 

 complicated digestive apparatus. In some of the inferior animals, the quantity of nu- 

 tritious material forms so small a part of the food that the digestive apparatus is even 

 more complicated than in the human subject. This is especially marked in the herbivora, 

 the flesh of which forms- an important part of the diet of man. In addition to what are 

 distinctly recognized as alimentary principles, food contains many substances having an 

 important influence on nutrition, which have never been isolated and analyzed, but 

 which render it agreeable. Many of these principles are developed in the process of 

 cooking. They will be considered, as far as practicable, in connection with the different 

 articles of diet. 



The alimentary principles belong to the inorganic, vegetable, and animal kingdoms, 

 and are generally divided into the following classes: 



1. Organic nitrogenized principles (albumen, fibrin, caseine, musculine, etc.), belong- 

 ing to the animal kingdom, and vegetable nitrogenized principles, such as gluten and 

 legumine. 



2. Organic non-nitrogenized principles (sugars, fats, and starch). 



3. Inorganic principles. 



Nitrogenized Alimentary Principles. 



In the nutrition of certain classes of animals, these principles are derived exclusively 

 from the animal kingdom, and in others, exclusively from the vegetable kingdom ; but 

 in man, who is omnivorous, both animals and vegetables contribute nitrogenized material. 

 In both animal and vegetable food, these principles are always found combined with 

 inorganic matters (water, chloride of sodium, the phosphates, sulphates, etc.), and fre- 

 quently with non-nitrogenized principles (sugar, starch, and fat). 



MwcuUne. Of the different nitrogenized principles used as food, musculine, albumen, 

 caseine, and fibrin are the most important. Musculine, the organic principle which forms 

 the bulk of the muscular substance, is perhaps the most important and abundant article 

 of this class. This substance is always united with more or less inorganic matter, which 

 cannot be separated without incineration. The flesh of different animals presents wide 

 differences in general appearance, in nutritive properties, and in flavor, which become 

 more marked after the formation of the odorous, empyreumatic substances which are 



