492 PRINCIPLES OF ANIMAL NUTRITION. 
the percentage expended in digestion, assimilation, and tissue build- 
ing varied only from 22.85 to 27.98. Expressing the same thing in 
absolute figures, we have the following: 
ENERGY PER GRAM OF ORGANIC MATTER. 
Expended in Diges- 
Gross, ‘tion, Assimilation, |. 
Cals. and Tasue 5 Building, 
Meadow hay........ 4.751 1.327 
Oat straw...........| 4.816° | 1.100 
Wheat straw........ 4.743 1.214 
Extracted straw.....| 4.251 1.190 
Average.......... 4.640 1.208 
ee 
In other words, the combined energy required to separate the 
digestible from the indigestible portion of one gram of organic 
matter, resorb it, and convert the resorbed portion into tissue was 
not greatly different for these four materials. They differed widely 
in their nutritive effect, not because of a greater or less expendi- 
ture of energy for these purposes, but chiefly because the same 
expenditure of energy resulted in making a much larger amount of 
material digestible in some cases than in others. 
CoNCENTRATED FEEDING-STUFFS.—A still more striking result is 
reached when we compare the results on coarse fodders with those 
on concentrated feeding-stufis. Taking the figures of Kellner’s 
experiments for the latter, and omitting his results on heavy 
rations of starch, we have the following data for starch, oil, and 
wheat gluten: 
ENERGY PER GRAM OF ORGANIC MATTER, 
Expended in 
Digestion, 
Gross, Assimilation, 
Cals. and Tissue 
Building, 
Cals. 
Starch (Kellner)..... 4.168 1.277 
OID exescs 2 panes ad ais 9.464 1.728 
Gluten (Kellner) . 5.742 2.284 
We thus reach the seemingly paradoxical result that the total 
expenditure of energy in the production of new tissue is decidedly 
