160 STATE BOARD OF AGRICULTURE. 



As will be seen from the above, food products are exceedingly complex sub- 

 stances. The compounds of greatest significance, however, are the inorganic com- 

 pounds, — water and mineral matter, and the organic compounds, — proteids, car? 

 bohydrates, cellulose and fat. These materials make up the bulk of all food 

 products. 



Water. — Water is present in all foods in varying amounts and is of exceeding 

 great importance in human and in animal nutrition. If it were not for water, 

 no food could be utilized, for the reason that it is the medium by means of which 

 food is conveyed to the tissue. Johnson has said, and very truthfully, that "next 

 to temperature water is the most potent factor in the production of a crop," and 

 what is true of water in relation to plant growth is likewise true in relation to 

 animal nutrition. Water might well be called the great lubricator of the digestive 

 system, and it is certainly because of the presence of water that foods can be 

 absorbed by the body. All plant tissue, and all animal tissue, contains a consid- 

 erable amount of water. All foods, in their ordinary condition, contain more 

 or less water. The porterhouse or round steaks, as purchased in the market, con- 

 tain over sixty per cent water, and vegetable products and cereal goods also contain 

 more or less of this substance. Water is the medium for the transportation of food 

 from one part of the body to another, and in a similar way is also the carrier 

 of the waste products from the body. An animal may exist for some time without 

 food, but Avill not, if deprived of water. 



Mineral Matter. — The mineral matter of a food is that part which remains 

 unconsumed when the food is burned. It is, as a rule, the smallest portion of 

 the food and occupies a som.ewhat minor place in animal nutrition. It is the 

 mineral part of the food which serves to build up the bony framework of the 

 body, and it seems to be indispensable to the normal action of the blood and the 

 digestive fluids. It is generally considered that some care should be given to the 

 food of growing children from the standpoint of mineral matter, for the frame- 

 work of their bodies is being constantly enlarged and strengthened, and this sup- 

 ply must come from the mineral matter of the food. Foods vary greatly in the 

 amount of mineral matter they contain. As we might expect, the mineral matter 

 in cereals is present to the greatest degree near the surface of the kernel and 

 hence the most of it is removed in the process of milling and appears in the 

 waste products. The bran from v/heat therefore, should contain a higher content 

 of mineral matter than the flour from the same wheat. In fact bran contains 

 on the average about ten times as much mineral matter as does the fine flour. 

 Excepting nitrogen, a crop robs the ground on which it is grown principally to 

 the extent of the mineral matter which it removes. The immense amount of 

 starch and sugar present in all crops did not cost the land a single pound of 

 real nutriment for it contains neither nitrogen nor mineral matter, however, 

 were it not for the presence of mineral matter in the soil not a single grain of 

 starch could be formed. Similarly, in human bodies, the total amount of ash or 

 mineral matter is quite small, and a large amount in the food is not desirable. 

 At the same time the presence of a certain minimum amount is quite necessairy 

 for it is closely associated with the utilization of the other factors in the food. 



TiiK Proteids. — It has been customary to consider the proteids as the most im- 

 portant substances concerned in the nutrition of man and animals. Certain it is 

 that none of the life processes go on in the absence of proteids. In what forms 

 they exist in the body is not known, but living tissue, when subjected to analysis, 

 always yields proteids. Proteids are the substances in the food least understood. 

 They differ essentially from therfats and carbohydrates in that they contain nitro- 

 gen. It is not in place here to discuss the various compounds coming under this 

 head, suffice it to say that the albumen of eggs, gluten of flour, casein of milk 

 and lean meat, are typical forms of proteids. It is highly essential that the food 

 of man shall contain considerable proteid substance, for the latter seems to be 

 quite intimately related to the life processes of the body. 



Fats. — Fats are substances which, as will be seen from the table, contain 

 simply carbon, hydrogen and oxygen. From this it might seem that they are 

 simple substances, but such is not the case. Fats from different sources vary 

 quite widely in the proportions of these three elements. In chemical terms, fats 

 are combinations of glycerine with organic acids. They are insoluble in water, 

 but easily soluble in ether and gasoline. On treatment with alkalies they may 

 be converted into soaps, and glycerine may be obtained as a by-product. The fats 



