502 PRINCIPLES OF ANIMAL NUTRITION. 
For 1 gram-meter, ascent.......... 0.0076681 cal. =3.259 gr.-m. 
ey, MW draftiescs ces aes 0.008180 “ =3.476 “ 
“* locomotion per kg. and meter.. 1.1787 cals. =500.95 “ 
According to the above figures the performance of one gram- 
meter of work required the metabolizing of material whose potential 
energy was equal to 3.259 gr.-m. in the one case and 3.476 gr.-m. in 
the other. In other words, these amounts of net available energy 
were liberated in the kinetic form in the body, one gram-meter in 
each case being recovered as external work while the remainder 
ultimately took the form of heat. 
This is equivalent to a utilization of 30.7 per cent. of the net 
available energy in ascent and of 28.77 per cent. in draft. It is to 
be noted that these figures refer only to that portion of the in- 
creased metabolism which is applied to the production of external 
work and do not include that necessary for the transportation of the 
animal’s weight. The corresponding ratio for this portion could 
only be obtained on the basis of complicated and uncertain compu- 
tations of the mechanical work of locomotion. If, however, instead 
of this we assume that this most common form of muscular activity 
is performed with the same economy as the work of ascent, we can 
conversely compute the mechanical work of locomotion for 1 kg. 
through 1 meter as 
500.95 gr.-m. X .307= 153.8 gr.-m. 
Experiments on Man.—In connection with his experiments on 
the dog already described, Zuntz * cites the results of a number of 
experiments with man upon the work of locomotion and of ascent, 
the average results of which are summarized in the table opposite, 
to which have been added the results of later experiments by 
Frentzel & Reach.t 
Experiments on the Horse.—Very extensive investigations on 
the production of work by the horse have been made by Zuntz in 
conjunction with Lehmann and Hagemann.{ Some of the results 
of these investigations have already been discussed in their bearing 
on the question of digestive work (pp. 385-393), and the method 
* Loc. cit., p. 208. 
+ Arch. ges Physiol., 88, 494. 
} Landw. Jahr., 18, 1; 23, 125; 27, Supp ITI. 
