162 STATE BOARD OF AGRICULTURE. 



dance in sorghum, sugar cane, sugar beets and maple sap, having the same formula 

 and properties from each of these various sources. It may be changed into 

 glucoses by the action of invertin and may then be further changed by yeast into 

 alcohol. 



Dextrin — (CeHipO^)!! is a product supposed to be intermediate between starch 

 and maltose. It is always produced when diastase acts on starch outside of the 

 body, but the amount produced in this way seems to depend largely on the tem- 

 perature to which the mass is submitted. It may be changed further into some of 

 the glucoses. Dextrin is used extensively as a base for the manufacture of 

 mucilage and differs from starch in being soluble in water. Starch, if heated for 

 a considerable time is gradually changed to dextrin. 



Cellulose — (Cf^H,nOs")n or fiber is a carbohydrate of the same cheirical composi- 

 tion as starch, but it is a decidedly different product. It is a colorless, insoluble 

 material composing the cell walls and woody fiber of plants. In the human system 

 the various ferments seem to have difficulty in dissolving it and hence we are 

 in the habit of cooking foods containing much fiber, so that the fluids of the body 

 may get to the starchy material supposed to underlie the cellulose layers. The 

 fiber or cellulose exists mostly in the rough, outer covering of the grain. In fact 

 it may be said with truth that the fiber and mineral substances inhabit for the 

 most part the same portions of the vegetable food products. 



LAWS OF NUTRITION. 



To Illustrate fully and clearly the data presented in this bulletin we shall dis- 

 cuss as briefly as possible some of the essential points concerned in the nutrition 

 of man.* In discussing this subject we must look at the problem from two stand- 

 points, first from the standpoint of the machine, and second from the physiological 

 standpoint. These two views in some instances are , antagonistic. 



Man is first of all a machine. His first duty, naturally, is to provide fuel for 

 the maintenance of his bodily mechanism. What he eats in excess of this may 

 fittingly be of a nature that conforms to his physiological and social surroundings, 

 without special regard to its properties from the standpoint of nutrition. Food 

 is supplied to the body then primarily as a fuel to maintain the temperature of 

 the body and to furnish energy for bodily work. In this respect the comparison 

 of man to an engine and of his food to the fuel supply of the boiler is a very apt 

 one. Fuel is supplied to maintain the temperature of the boiler so that steam 

 may be produced and work be done. Exactly in the same way, food is taken by 

 man in order that his bodily heat may be kept up and the life processes may go 

 on. Every contraction of muscle, even the beating of the heart and that con- 

 cerned in the process of breathing requires the combustion of food material already 

 in the body and food must be supplied from outside sources or these life processes 

 are, of necessity, of short duration. The body, if unable to procure food or fuel 

 from external sources, draws upon the stored up supply in itself, as in sickness, 

 and the person is then said to "consume his own flesh." 



A food is any substance which, taken into the system, builds tissue or yields 

 energy xohich is of use in the performance of natural functions.-^ 



To be a food, from a mechanical point of view, the substance must be capable 

 of yielding energy, that is, it must be in a condition in which it can be burned in 

 the'body to produce heat and muscular activity. Foods are classified, mechanically, 

 according to their heat producing powers in exactly the same way that fuels for 

 a boiler are classified. 



Chemistry recognizes six general divisions of all foods, namely: 



1. Protein — (gluten, albumen, casein, etc.). 



2. Fiber — (cellulose). 



3. Carbohydrates — (sugars, starch, etc.). 



*It is exceedingly difficult to describe in non-technical language the principles of human nutri- 

 tion, and while the discussions herein given are not very extended, possibly they may give to the 

 average reader a somewhat clearer understanding of those laws. It may be well to state here that 

 the author has felt for some time that altogether too much stress is laid on the concentrated food 

 idea and what observations he has been able to make, together with a study of the nutritive pro- 

 cesses as influenced by different foods have quite inclined him to believe that in the human system, 

 at least, it is not so much the digestibility of the food that determines its value in the dietary, 

 as its wholesomeness as influenced by compounds not considered, necessarily, as concentrates which 

 are present and which in themselves may not be highly nutritious. 



tSee "Bunge" Physiologic & Pathologic Chemistry, Chap. IV. 



