446 DEPOSITION OF FAT AND FLESH IN THE BODY. 



wholly replace fat in the process of metabolism. The smallest amount of lean meat 

 that thus maintains the metabolic equilibrium is designated by Pfluger as the 

 nutritive requirement. The supply of fat or carbohydrates exclusively is never 

 capable of maintaining life, as the animal under such circumstances is compelled 

 to consume its own flesh. Therefore, a certain indispensable amount of proteid 

 must absolutely be present in every diet. 



If an amount of proteid be added to the food that is sufficient in itself to. 

 fulfil the requirement and if any desired amount of fat is added, almost all of 

 the proteid will be decomposed and almost all of the fat will be deposited as such. 

 The conditions are much the same if carbohydrate is supplied instead of fat, 

 except that in this case the carbohydrate is transformed in the body into fat 

 and is deposited as such. The greater the amount of non-nitrogenous food that 

 is supplied in addition to the nutritive requirement of proteid the more favorable 

 are the conditions for fattening, because all of the non-nitrogenous matters are 

 transformed into bodily fat. 



If proteid is not supplied in sufficient amount the deficiency may be made 

 good by fat or carbohydrate, and in such proportion that two-thirds of the nutritive 

 requirement may be supplied by non-nitrogenous matters. Under such circum- 

 stances the latter replace the deficiency of proteid in accordance with the amount 

 of their potential energy as indicated by the number of calories yielded in their 

 combustion. From these facts it follows that the greater or smaller amount of 

 albumin supplied with such food is decomposed almost wholly in the process of 

 metabolism, indifferently whether much or little fat or carbohydrate is sup- 

 plied at the same time. In direct contrast to the proteid, the amount of fat or 

 carbohydrate that is consumed in the process of metabolism is in nowise dependent 

 upon the amount thereof contained in the food. Generally, the amount of carbo- 

 hydrate or fat that undergoes decomposition is the smaller the larger the amount 

 of proteid supplied. The nutritive requirement is satisfied first and foremost by 

 proteid, but if the amount of proteid supplied is not sufficient, the fats and the 

 carbohydrates are also utilized in so far as the requirements demand. In order 

 to comprehend the laws of fattening by' means of proteid and starch, it should 

 be borne in mind that for the satisfaction of the nutritive requirement, in addition 

 to almost the entire amount of proteid supplied, so much carbohydrate is decom- 

 posed as will wholly suffice for the nutritive requirement. The amount of carbo- 

 hydrate left over is deposited as fat. In accordance with the foregoing statements, 

 on supplying equal amounts of carbohydrate a proportionately larger amount 

 will be conserved the larger the amount of proteid furnished. 



The amount of nutritive requirement, that is, the smallest amount of fat-free 

 meat that alone establishes metabolic equilibrium, is governed by the flesh-weight 

 of the animal and increases in direct proportion to this. A fat animal has, there- 

 fore, apparently a smaller nutritive requirement only because the total amount 

 of fat, acting as a similar amount of dead matter, consumes nothing. 



The decomposition in the process of metabolism of the proteid taken with 

 the food increases with the supply, even when this far exceeds the requirement, 

 but a portion of the excess is always conserved. In this manner there is a gradual 

 deposition of flesh in the body. 



As the amount of proteid supplied with the food has practically no influence 

 upon the deposition of fat in the body, and the carbohydrates are generally not 

 so useful as proteid, fat will be produced most advantageously with the smallest 

 amount of proteid possible, but with the largest possible amount of starch in 

 the food. If an animal on a mixed diet in a moderate state of fattening be given 

 a further supply of proteid, this will at once satisfy a portion of the nutritive 

 requirement, which theretofore had been satisfied by non-nitrogenous matters. 

 These therefore can be dispensed with and are deposited as fat. 



With a diet of meat exclusively deposition of flesh is possible only when the 

 proteid of the food exceeds the requirement. The largest portion of the excess 

 of proteid is decomposed and some is deposited. With increase in the weight of 

 flesh, the consumption of proteid soon increases, and, accordingly, the amount of 

 excess diminishes. It is, therefore, one of the properties of proteid food that it 

 tends speedily to neutralize the conditions necessary for the deposition of flesh 

 if these are present. 



With a mixed diet deposition of flesh can be attained only if the supply of 

 proteid exceeds the amount indispensable. Under such circumstances only from 

 7 to 9 per cent, on the average, at most 16 per cent., of the proteid supplied, is 

 conserved by the non-nitrogenous articles of food. The deposition of flesh is then 

 the greater the larger the amount of proteid contained in the food. Of the proteid 



