THE UTILIZATION OF ENERGY. 493 
greater in the case of these three materials, and notably the last 
two, than in the four coarse fodders previously tabulated. 
The paradox largely disappears, however, when we remember 
that while the larger share of the work of digéstion has to do with 
the total dry matter of the food, the work of assimilation and tissue 
building has to be performed only upon the digested matter, and 
that the proportion of the latter is much larger in the starch, oil, 
and gluten than in the coarse fodders. We have already (pp. 375 
and 445) seen reason to suppose that the processes of assimilation 
and tissue building consume a éonsiderable share of the metaboliz- 
able energy of the food, although we are still ignorant as to how 
much and as to how the proportion differs with different materials, 
and the above results serve to confirm this conclusion. 
If, simply as an illustration, we assume that the uniform pro- 
portion of 30 per cent. of the metabolizable energy of the several 
feeding-stuffs is thus consumed, then'if we deduct this amount from 
the totals above computed we shall have the work of digestion alone 
as follows: 
ENERGY PER GRAM OF ORGANIC MATTER. 
yore 
pes eas Assimilation Total, Ee: Work of 
Enerey and Tissue enditure Digestion Alone, 
(p. 297), Building 2s é io e Cals. 
Cals. (30 Per Cent. Bree 
‘|. of Metaboliz- 
able), Cals. 
- Meadow hay............ 2.213 | 0.664 1.327 0.663 | 
Oat straw............4.. 1.724 0.517 1.100 0.583 0.672 
Wheat straw............ 1.475 0.443 1.214 0.771 [-° 
Extracted straw......... 3.213 0.964 1.190 0.192 
Starch (Kellner) ........ 3.079 0.923 1,277 0.354 
6] ree ere re 5.298 1.589 1.728 0.139 
Wheat gluten (Kellner)..; 3.831 1.149 2.284 1.105 
This arbitrary assumption reduces the work of digestion of the 
starch to about one half that expended upon a like amount of mate- 
rial in the form of coarse fodders which yield chiefly carbohydrates 
to the organism. Moreover, we must remember that in the case of 
starch there is a considerably greater loss of energy in the methane 
fermentation than with the same amount of total organic matter 
in coarse fodders, and that this loss is included in the work of diges- 
tion. The high figure found for the wheat gluten we might be 
