THE BALANCE OF NUTRITION 195 



elusion, and when accompanied by a complete knowledge of 

 the chemical ingredients found in feeding stuffs, they will make 

 it possible to give an exhaustive account of nutrition as a physico- 

 chemical process. It is hardly necessary to say that the reali- 

 zation of this ideal lies in the distant future. 



279. Total nutritive effect. Meanwhile, students of stock 

 feeding are interested primarily in a somewhat different aspect 

 of the subject, viz., in the aggregate effect of the varied and com- 

 plex metabolic processes in reducing, maintaining or increasing 

 the stock of matter and of chemical energy in the body. Is the 

 body under any given regimen maintaining itself and making 

 due growth, or is the animal doing work or yielding milk or 

 other products at the expense of its own tissues? This is evi- 

 dently a question of balance. Is the income of the body equal 

 to its outgo ? 



280. The schematic body. The idea of the organism as 

 dependent upon a balance between constructive and destructive 

 activities may be made more specific by means of the conception 

 of the schematic body, which regards the body of the animal, 

 aside from water, as consisting essentially of ash, protein and 

 fat, together with an amount of glycogen so small that it may for 

 many purposes be neglected. 



The justification for this conception is found in the data con- 

 tained in Chapter II, 3, regarding the composition of the animal 

 as a whole. It will be recalled that in the investigations there 

 recorded the water, ash and fat were determined directly, the 

 difference between the sum of these and the total weight of the 

 animal, of course, showing the amount of fat- and ash-free dry 

 matter. In those cases in which the total nitrogen contained 

 in the body was also determined, it appeared (99) that, with 

 one exception, the percentage of nitrogen in this fat- and ash-free 

 dry matter closely approximated that in the animal proteins. 

 In other words, the amount of glycogen and other substances 

 included in the fat- and ash-free dry matter is so small as to be 

 negligible and the latter may be considered to consist essen- 

 tially of protein. 



From this point of view, it is evident that the effect of any 

 feeding stuff or ration in causing a gain or preventing a loss of 

 ash, protein and fat (and glycogen) shows its aggregate nutri- 

 tive effect. Or, since the organic matter of the body may be 



