Food in Relation to Work. 135 
tion of tissue. Increased destruction would necesssitate 
increased elimination of nitrogen in the excretions, since 
nitrogen plays such a prominent part in the composition 
of muscular tissue ; and consequently the amount of elimi- 
nated nitrogen would be directly related to the amount 
of work done. 
Proceeding on these lines, numerous observers submit- 
ted Liebig'S theory to the test of experiment ; but the 
first decisive blow was struck by two German scientists, 
FlCK andWlSLICENUS, the one professor of physiology and 
the other of chemistry at Zurich. Their mode of pro- 
cedure was to observe the elimination of nitrogen under 
ordinary condition as regards work, but under a strictly 
non-nitrogenous diet. Severe muscular work was then 
to be undertaken, still under a non-nitrogenous diet, and 
the elimination of nitrogen again watched. 
By these means, if the source of muscular powers 
consisted in the destruction of the muscles themselves 
the amount of nitrogen egested during the " work" 
period ought to be greatly increased. 
The work chosen to be performed was the ascent of 
the Faulhorn, a mountain in the Bernese Oberland, 
between 6,000 and 7,000 feet in height. The day previous 
to the ascent was passed on a purely non-nitrogenous 
diet, and from the time of the cessation of nitrogenous 
diet, the eliminated nitrogen was observed to undergo 
a decided and progressive diminution. The next day, 
on a similar diet, the ascent was effected. No in- 
crease was observed during this period in the amount 
of eliminated nitrogen. On the evening of the day of 
the ascent, after a brief interval of rest nitrogenous food 
