560 The American Naturalist. [July, 
ure in the expense account, and that the work donein shaping 
and fitting the materials in proper relations, represent a very 
large proportion of the real cost of the machine or of the 
repairs that may be made. In repairing a machine, a few 
cents may pay for the iron or wood used, while several dollars 
would be required to pay for the work done. 
The same principle holds good with the animal machine, 
both in its original construction and its repairs. But a small 
proportion of the food constituents are utilized in the processes 
of nutrition, and a very large amount of energy is constantly 
expended in the work. of transforming these materials into 
animal substance and animal products. 
The real significance of these facts will best be seen by 
making a quantitative estimate of the energy expended, and 
the transformations it undergoes in organic processes, as repre- 
sented in the following table giving an approximate state- 
ment of the composition of one acre of corn, and of a fat ox 
analyzed at Rothamsted. 
PE TEENS AS E TD Tries oon ie een S ENS ale 
FECE TE EUN. 
SRE eee) MIR T PHP EN EM 
SHOEI rere AA ae wd NM FS 
RSEN ES PT MAT 
Corn one Acre, io: ' 
cae | mer p qon qmi, 
7200 Ibs. total bs. ). 
Per cent. Lbs. Per cent. Lbs. 
Carbon 39.7 2858 31.6 448 
Sion 7.0 504 9.7 137 
À Oxygen 48.8 3511 46.5 660 
Nitrogen 1.3 90 24 m 
— 3.3 237 3.9 55 
Potash 1.10 79 0.18 2.6 
Phos. Acid. 0.53 38 1.55 22 
Water 17.1 1232 | 45.5 646 
Proteids 7.8 562 || 14.5 206 
Fat 3.3 237 || 30.1 427 
Carbhydrates 68.5 4932 || 7 
B Ash 3.3 37 — i 3.9 55 
| Potash 1.10 79 | | 0.18 2.6 
Phos. Acid} 0.58 "EN 1.55 22 
