EQUILIBRIUM OF THE METABOLISM. 477 



whole of the N cannot be recovered from these excretions, but on the 

 contrary there is a considerable deficit. 



According to Seegen and Nowak, 1 kilo, weight of a living animal excretes of 

 gaseous N per hour, thus rabbit, 4-5 milligrammes (according to Leo, only T a 5 of 

 this value); dog, 8 milligrammes ; fowls, pigeons, 7-9 milligrammes. According 

 to Leo, only '55 per cent, of the albumin transformed within the body (assuming 

 15 per cent. N in albumin) is given off in the form of gaseous N. 



The H leaves the body chiefly in the form of water a part, however, is in 

 combination in other excreta; the is chiefly excreted as C0 2 and water; a little 

 is given off in combination in other excreta; water is given off by evaporation from 

 the lungs and skin. As H is oxidised to form H 2 0, more water is excreted than 

 is taken in. With regard to the salts, most of the readily soluble salts are given 

 off by the m*ine; less, especially potash salts and rather insoluble salts, in the 

 fteces, while others, e.g., common salt, are given off in the sweat. Of the sulphur 

 of albumin, about one-half is excreted in the sulphur compounds in the urine, 

 and the other half in the fteces (taurin) and in the epidermal tissues. 



Every body has a minimum and a maximum limit with reference to 

 its metabolism, according to the amount of work done by the body, 

 and its weight. If less food be given than is necessary to maintain the 

 former, the body loses weight; while, if more be given after the 

 maximum limit is reached, the food so given is not absorbed, but 

 remains as a floating balance and is given off with the faeces. When 

 food is liberally supplied and the weight increases, of course the 

 minimum limit rises; hence, during the process of "feeding" or 

 " fattening," the income necessary is very much greater than in poorly- 

 fed animals, for the same increase of the body-weight. By continuing 

 the process, a condition is at last reached, in which the digestive 

 organs are just sufficient to maintain the existing condition, but cannot 

 act so as to admit of new additions being made to the body-weight 

 (v. Bischoff, v. Voit, v. Pettenkofer). 



By the term " luxus consumption " is meant the direct combustion 

 or oxidation of the superfluous food stuffs absorbed into the blood. 

 This, however, does not exist ; on the contrary, the material in the 

 juices is always being used for building up the tissues. The albumin 

 found in the fluids, which everywhere permeate the tissues, has been 

 called " circulating albumin" and, according to v. Voit, it may undergo 

 decomposition sooner than the organised " organ albumin" which forms 

 an integral part of the tissues. 



According to v. Voit only 1 per cent, of the organ albumin present in 

 the body, while 70 per cent, of the circulating albumin, is transformed 

 in 24 hours. 



The excretion of N after taking food is not equal from hour to hour ; it rises 

 rapidly at first, reaches a maximum in 5-6 hours, and then gradually falls. The 

 same is the case with the excretion of S and P, only in these cases, after a flesh 

 diet, the maximum is reached at the fourth hour. After the addition of fat to a 



