THE FASTING METABOLISM. 81 
and subsequently the total metabolism as shown by the combined 
nitrogen and carbon balance. 
§ 1. The Proteid Metabolism. 
Tenps TO BEcomE Constant.—When food is withheld from a 
well-nourished animal, particularly a carnivorous animal, the proteid 
metabolism usually diminishes, at first rapidly and more slowly later, 
until within a few days it reaches a minimum value which may then 
remain nearly unchanged for a considerable time. This was first 
shown by the investigations of Carl Voit, in conjunction with 
Bischoff and later with v. Pettenkofer, and has been fully confirmed 
by later results. 
The following table shows the results obtained by Voit * in. 
several experiments upon a dog weighing about 35 kgs., the pro- 
teid metabolism being expressed in grams of urea per day. “As 
noted in Chapter III, such results are not absolutely accurate and do 
not represent the total proteid metabolism, but the fact that they 
are comparable is sufficient for our present purpose. 
Previous Food per Day. 
2500 G: 7 Mteats | 1500 G 1500 G: 
rms. eat; 500 Grms. rms. A 
Meat. |250Grms.| Meat. Meat. Nothing. 
Fat. 
Urea per day: Grms. Grms. Grms. Grms. Grms. 
Last day of feeding....| 180.8 180.0 110.8 110.8 24.7 
1st <‘ ‘* fasting..... 60.1 37.5 29.7 26.5 19.6 
nd meer car 24.9 23.3 18.2 18.6 15.6 
ie (6 jens 19.1 16.7 17.5 15.7 14.9 
4th “ « Ee wars 17.3 14.8 14.9 14.9 18.2 
Sth “ OE cy eia ts 12.3 12.6 14.2 14.8 12.7 
6th “ * fe oanauens “13.3 12.8 13.0 12.8 13.0 
th “« « 6 (atabars 12.5 12.0 12.1 12.9 
8th “ f  laeee 10.1 |......06- 12.9 12.1 
9th “« “ GE crated silo ~ 09 efete le faaele'srs's’staial| siaeisrine<e4ie 11.9 
10th “ “ Oo Sacad la. eie ae eianale | aha 3 a's 4 Ba) ree Sax 11.4 
Two Factors oF Proreip MeTasorism.—In these, as in many 
similar experiments, the proteid metabolism was quite unequal on 
the last day of the feeding and on the first fasting day, but in a 
* Zeit. £. Biol., 2, 311. 
