790 The American Naturalist. [October, 
extensive series of analyses made there, furnish the most con- 
venient and only reliable data for our purpose in the case of 
fattening animals. The average results with oxen, sheep and 
pigs, as estimated by Sir John Lawes several years ago, and 
the feed consumed and increase made by the “analyzed fat 
pig” have been taken as the basis for calculating the expendi- 
tures of energy as given in the following tables. 
In making a comparable estimate of the expenditures of en- 
ergy in milk production, the record of a Guernsey cow at the 
New York experiment station in 1891, appeared to answer the 
required conditions, as detailed statements of the composition 
of the food consumed and milk produced were given, and the 
dry substance of the milk for each month differed but little 
from the dry substance of the 100 pounds of increase in the 
fattening animals under consideration, indicating in a general 
way ‘that nearly the same amount of work had been required 
in its production. 
The factors used in estimating the potential energy of or- 
ganic substances (based on experiments of Berthelot and 
TABLE 2. 
Expenditures of energy in fattening oxen, sheep and pigs, to produce 100 
pounds of increase in live weight; and a similar estimate of the expenditures of 
energy in milk production. In foot-tons of work. 
Sa |Be | a |ske 
oO a “o 
i ca 3 & 9 
ey ape 
°3 | om MS BIS 
cb aie 32% aw r 2 
BS agg | oa | 28-34 
3 F: E Mog 45 a BES 
pS aA z.s HD me eae 
Oxen 3,389,929 | 413,558 | 955,790 | 2,020,580 
Sheep 2,809,787 | 440,584 | 655,967 | 1,713,240 
Pigs ; 1,269,181 457,800 175,674 | 635,699 
“ Analysed fat pig” 1,478,393 | 435,160 | 272,335 770, 900 
In 557 Ibs. 
milk. 
a April 1,610,800 i een 581,573 | 699,840 
yuernsey n 
Cow 7 = milk. : te 
May 1,626,678 | 349,440 | 564,020 | 713,230 
