278 ITS BEAEING ON MEDICAL PRACTICE. 



During the five days of observation the work done, expressed in hor- 

 izontal miles of walking, was as follows : 



First day. 



Miles. 



Miles walked 11. 4 



Height ascended 1,800 feet = 10. 2 



21.6 



Second day. 



Miles walked 12. 



Height ascended 2,400 feet = 13. 7 



25. 



Third day. 



Miles walked 11 - (> 



Height ascended 1,400 feet = 8. 



19.6 



Fourth day. 



Miles walked 9. 3 



Height ascended 1,400 feet = 8. 



17.3 



Fifth day. 



Miles walked - 10. 4 



Height ascended 1,600 feet = 9. 1 



19.5 



From the preceding statement it follows that the average work doue 

 each day was 20.74 miles of horizontal walking, the result of which upon 

 the urea excreted was to be compared with the result already meutioiied 

 as a physiological constant, determined under circumstances in which 

 the daily muscular work never exceeded five miles of horizontal walking. 



In order to determine the urea, I collected each day all the urine passed, 

 and kept one-fifth part of it; and at the close of the fifth day examined 

 the mixture formed from the five days' urine. It was found to contain 

 501.16 grains of urea per day — a result practically identical with the 

 physiological quantity previously found by me under totally different 

 conditions, viz, 501.28 grains. I was much surprised at this result, for 

 I had previously believed in the theory laid down by Liebig, which at- 

 tributed the excretion of urea to the disintegration of muscular tissue. 



It might be objected to the preceding reasoning that the combustion 

 of proteinic compounds represented by 501.28 grains of urea ex(u-eted is 



