THE RELATIONS OF METABOLISM TO FOOD-SUPPLY. 99 
confirm those of Feder. Sherman and Hawk * have likewise found 
the curve of nitrogen excretion by man after the ingestion of lean 
meat to show the same general form observed by Feder and by Graf- 
fenberger. 
NITROGEN CLEAVAGE INDEPENDENT oF ToTaL METABOLISM.— 
Kaufmann,f by the method outlined in Chapter VIII, has made 
a series of determinations of the nitrogen excretion, respiratory 
exchange, and heat production of dogs during the time when nitro- 
gen cleavage is most active, i.e., from the second to the seventh hour 
after a full meal‘of meat. From his theoretical equations for the 
complete metabolism of proteids (pp. 51 & 75) he computes the 
respiratory exchange and heat production corresponding to the 
observed excretion of urinary nitrogen and compares them with 
the actual results per hour as follows: 
Proteid Computed. Observed. 
volar: ‘4 
Gime: | chien denentaal aneuion: joxereied. Gonened| dustin, 
Liters. Liters, Cals. Liters. Liters. Cals. 
No. 1.. 9.329 8.132 9.745 45.0 5.953 6.767 30.6 
EBS Dis 9.926 8.565 | 10.373 48.0 7.064 7.972 34.6 
tb 8 eg 9.350 8.153 9.771 45.4 7.161 8.236 34.0 
ee oe 9.540 8.231 9.864 45.8 7.398 8.673 34.0 
ee 6.632 5.783 6.930 32.0 5.228 6.596 27.7 
EY 3B 208 9.491 8.276 9.918 46.1 6.393 7.813 29.7 
ee eee 8.685 7.573 9.075 42.2 6.325 7.730 29.0 
BO Bote 9.958 8.683 | 10.406 48.4 6.702 7.903 33.6 
Oe Oss 8.928 7.785 9.235 43.0 6.062 7.916 35.3 
* 10...) 10.553 9.202 | 11.027 51.0 7.125 8.589 32.7 
But a glance is needed to show that the total metabolism, 
whether measured by the gaseous exchange or by the heat produc- 
tion, is much less than that computed, which is equivalent to saying 
that the non-nitrogenous residue of the proteids was not completely 
oxidized. Gruber,§ whose experimental results upon the rate of 
nitrogen excretion fully confirm those above cited, has shown very 
clearly the bearing of these facts. He points out that if we 
* Amer. Jour. Physiol., 4, 25. 
+ Archives de Physiologie, 1896, pp. 346 and 768. 
+ Kaufmann’s factor for proteids, derived from the formula C,,H4,Nj,0..8, 
is 6.39. 
§ Zeit. f. Biol., 42, 407. 
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