METABOLISM. 
Urea Excretion in Grammes per Diem. 
Day of 
Inanition. 
Series I. 
Series II. 
Series III. 
1 
601 
26-5 
13-S 
2 
24-9 
18-6 
11-5 
3 
19-1 
15-7 
10-2 
4 
17-3 
14-9 
12-2 
5 
12-3 
14-8 
12-1 
6 
13-3 
12-8 
12-6 
/ 
12-5 
12-9 
11-3 
8 
10-1 
12-1 
107 
to vary greatly with different dogs ; small animals metabolise more 
proteid per kilo, than large ; lean animals more than fat. Small dogs 
have a larger proportionate surface, and relatively a smaller amount of 
body-fat. 1 
Many similar observations have been made on fasting men. One 
of these (Cetti) was under observation at different times and by 
different observers. His weight was about 57 kilos. The amount of 
urea excreted per diem, during the first ten days of fasting, was a little 
over 20 grms., equivalent to from 10 to 11 grms. N. Another (younger) 
man, weighing about 60 kilos., was also found by I. Munk to excrete per 
diem, during the first ten days of fasting, about 11 grms. N, representing 
an average loss per diem of about 70 grms. proteid. In these cases there 
was but little body-fat. In other individuals, in which there was abund- 
ance of body-fat, the N excreted has been found to be much less. Thus 
Succi (weight 63 kilos, at beginning, 52 kilos, at end of period) was found 
by Luciani, during a thirty days' fast, to excrete on the tenth day 
6*7 grms. ; on the twentieth, 4 - 3 grms. ; and on the last day 3 - 2 grms. N ; 
and Jacques (62 kilos.), observed by Noel Paton and Stockman, gave an 
average daily loss of 5 - 29 X. Praussnitz determined the amount of N 
excreted by ten persons during the second day of fasting, and found the 
average, for a man weighing about 70 kilos., to be 13 "7 grms., equivalent 
to a loss of 90 grms. proteid per diem, or about 1'2 grms. per kilo, 
body weight. This may therefore be regarded as representing the 
amount which it is absolutely necessary to supply in the food, for the 
maintenance of nitrogenous equilibrium. 
In herbivora there may be an actual increase in the nitrogenous excreta 
at the beginning of a starvation period, instead of a diminution ; due to 
the fact that, under these circumstances, such animals, being reduced to living 
upon their tissues, become practically carnivorous. As in carnivora, such 
increase may become greater towards the end of inanition, in consequence of 
the exhaustion of the fat of the body, and an increased destruction of the tissue 
proteids. 2 
Now, the amount of urea in the urine during a fasting period of not 
too long duration is probably a definite measure of the necessary de- 
struction of tissue proteid which goes on within the body, and it may 
therefore be taken as a result of such experiments, that the amount of 
this metabolism is fairly constant. Such destruction occurs in spite of 
1 Rubner, Ztschr. f. Biol., Miinchen, 1883, B<1. xix. S. 535. 
2 Rubner, ibid., 1881, Bd. xvii. S. 214; Heymans, Bull. 
Bruxelles, 1S96, p. 38. 
Acad. roy. d. sc. de Bebj., 
