Origin of Muscular Power. 493 



A glance at these Tables furnishes a new testimony to the 

 fact, which has often been before experimentally proved, that 

 muscular exertion does not notably increase the excretion of 

 nitrogen through the urine. It declined in our experiment 

 tolerably regularly from the 29th of August till the evening 

 of the 30th*, evidently in consequence of abstinence from food 

 containing nitrogen. In the night of the 30th to the 31st, in 

 spite of the plentiful meal of albuminous food on the evening 

 of the 30th, the secretion of nitrogen was less than on the pre- 

 ceding night. The reason of this perhaps was that during 

 abstinence the secretion of nitrogen (never entirely discontinued) 

 was carried on at the expense of tissues, and now these tissues 

 had first of all to be repaired. We will not pursue such consi- 

 derations further, but will apply our figures to other conclusions. 



We must, it is true, in the first place take our stand upon an 

 hypothesis, which, however, has been well established by many 

 recent investigations. We assume, namely, that the nitrogen of 

 the oxidized albumen leaves the body entirely through the urine. 

 In fact it has lately been proved, on the one hand by Kanke, on 

 the other by Thiry, that neither by the perspiration nor by the 

 breath is any perceptible quantity of nitrogen disposed of. For- 

 tunately we are further in a position to state that during the 

 ascent of the mountain we neither of us perspired to a perceptible 

 degree. During the whole ascent we were enveloped in a cold 

 mist, which prevented us from becoming overheated. Even if 

 any noticeable amount of nitrogen were excreted with the fasces, 

 we should yet be justified in the preceding experiment in neg- 

 lecting it ; for the nitrogenous products of the transmutation of 

 albumen which might possibly be contained in the faeces are 

 doubtless not highly oxidized compounds, and no heat. worth 

 mentioning is liberated in their production. 



We have now to consider, on the preceding assumptions, what 

 is the largest amount of albumen that can have been oxidized in 

 our bodies during the ascent of the mountain. We think we 

 should be justified in not estimating the albumen oxidized 

 during the hours of work higher than was calculated from the 

 quantity of nitrogen excreted in the work urine (viz. 22*09 for 

 rick, 20-89 for Wislicenus). In fact the rate of the nitrogen 

 excretion seems to be so entirely regulated by the supply of food, 

 and so completely independent of muscular action, that we can 

 reasonably suppose it to depend only upon the decomposition of 

 protein substances. If any one were to maintain that at the 



* The slight apparent deviation of the numbers under Wislicenus ought 

 hardly to come into consideration, as they may easily have been affected 

 by the retention of some urine in the bladder, or by other similar dis- 

 turbances. 



