THE UTILIZATION OF ENERGY. 529 
results obtained by Kellner regarding the influence of excessive 
work upon the proteid metabolism of the horse. It was there shown 
that when the work was increased beyond a certain amount there 
resulted a prompt increase of the urinary nitrogen and at the same 
time a steady falling off in the live weight. The method employed 
in Wolff’s experiments, and which originated with Kellner, is based 
upon this fact. It may perhaps be best illustrated by one of 
Kellner’s earliest experiments,* in which starch was added to a 
basal ration, the results of which have already been referred to in 
Chapter VI (p. 199). 
In the first period the daily ration consisted of 6 kgs. of oats 
and 6 kgs. of hay, while in the second period 1 kg. of rice starch was 
added. Digestion trials showed that there was digested from these 
rations the following: 
Period I, Period II, Increase. 
Grms. Grms. Grms. 
Crude protein .............-260- 757 .07 750.53 — 6.54 
pe DEL es. os see sega bees eee 636.10 713.40 + 77.30 
Nitrogen-free extract ........... 3874 .36 4488 .15 +613.79 
Ether extract ...........-..-065 279.45 275.43 — 4.02 
5546 .98 6227 .51 +680 .53 
The work was performed in a special sweep-power which was 
so constructed as to act as a dynamometer. With a uniform draft 
of 76 kgs., the daily work in the four subdivisions of the first 
period consisted of 300, 600, 500, and 400 revolutions respectively, 
while in the two subdivisions of the second period it was 800 and 
600 respectively. From the daily results for live weight and urinary 
nitrogen and from a comparison with another period in which 1.5 
kgs. of starch was fed, Kellner concludes that the maximum amounts 
of work which the animal could perform without causing an increase 
in its proteid metabolism and a decrease in its live weight were for 
the first period 500 revolutions and for the second period 700 revo- 
lutions. The difference of 200 revolutions, then, represents the 
additional work derived from the added starch. Two hundred 
revolutions with a draft of 76 kgs. equaled 438,712 kgm., to which’ 
is to be added the work of locomotion, estimated by Kellner (com- 
* Landw. Jahrb., 9, 670. 
