THE UTILIZATION OF ENERGY. 465 
; Metsholizable Energy of en 
Period. Added Food, | Resulting Gain. | “Wfitized: 
Cals. B 
1 ees 588.4 517.8 88.00 
Conglutin: J TID... 22221221! 1100.3 741.8 67.42 
Wess 7) 1639/2 1106.8 67.51 
Se Eesha 1131.7 672.5 59.41 
Flesh-meal: | eee ee 454.9 315.7 69.39 
A computation based on the observed amounts of methane 
would affect the above figures in two ways. First, if the added 
proteids diminished the production of methane, this was equivalent 
to an increase in the apparent metabolizable energy of the food, 
and the figures for the latter must be correspondingly increased. 
Second, the gain of fat will also appear relatively greater in the 
intermediate periods, II-VI, and the figures for the energy of the 
gain must also be increased. Computed on this basis the results 
are: 
: Energy of Energy of | Per Cent. 
Period. cas in ees Resale Gain, Pore a 
TR staan See ae 715.4 605.7 84.68 
Conglutin: Wee betes eid 1245 38 842.4 67 .63 
TW cece eds 5 1902.3 1288.8 67.76 
’ Flesh: 1: Wiiserae eal eke 1288 .2 780.7 60.59 
osdacmasual a> A nema ee 582.1 403 .6 69.33 
No obvious explanation of the exceptionally high results ob- 
tained in Period Il presents itself. Those of the remaining 
periods do not seem to indicate any considerable differences in the 
utilization of different quantities. The figures are notably higher 
than those computed from the Méckern experiments, but in view 
of the uncertainties attaching to them too much stress should not 
be laid on this fact. 
Discussion of Results. 
As was pointed out at the beginning of this section, and as was 
further apparent in considering the results of experiments upon 
carnivora, our knowledge of the net availability of the energy of 
feeding-stuffs and nutrients is too imperfect to permit the experi- 
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