1894.] - Animal Mechanics. 561 
17 083 000 foot-tons, equiva- j 3, 381,000 foot-tons, equivá- 
Stored umi d song 
ork don 
lent to the 
day and night for 142 days, 
continuously for 719 days. 
A chemical analysis of the corn shows (division A of the 
table), that it is composed of 2858 lbs. of carbon; 504 lbs. of 
hydrogen; 3511 lbs. of oxgen; 90 lbs. of nitrogen; and 
237 lbs. of ash, or mineral constituents, the most important of 
which are potash 79 lbs., and phosphoric acid 38 lbs. "Theash 
constituents and the nitrogen are alone derived from the 
soil. 
We have here the elements of which the crop is composed, 
but division B of the table shows that they represent water 
1232 lbs.; proteids 562 lbs.; carbhydrates 4932 Ibs.; and ash 
237 lbs. "These are the facts furnished by chemistry in regard 
to the composition of the acre of corn, but they do not repre- 
sent the whole truth. 
To transform the simple elements of division A of the able 
into the complex organic compounds of division B, energy 
must be expended and work done, and the energy so used is 
stored up in the organic substances formed as an essential con- 
dition of their constitution. The amountof this stored energy 
is represented in division C of the table, and it is an import- 
ant factor in the composition of the crop of corn, as it is one 
of the essentials in animal nutrition. 
This stored energy of the corn does not, however, represent 
the total expenditure in the growth ofthe crop. Experiments 
show that for each pound of dry organic substance formed by 
the growing corn, about 300 lbs. of water will be exhaled, or 
thrown off by the plants in the form of vapor. To convert 
water into vapor involves an expenditure of energy, and this 
for the acre of corn would be approximately equivalent to the 
work of 24 horses for six months without intermission. Water 
is likewise evaporated from the soil as one of the essential con- 
ditions of fertility, and this calls for a further expenditure of 
energy, which under our climatic conditions may be estimated 
at about twice the amount expended in exhalation from the 
plants themselves. Taking all of these processes together, the 
