URINE. 169 



blood as a consequence of peripheral nutrition, but that it is 

 formed during those processes which are dependent on the 

 respiratory and circulatory functions, in which we must seek for 

 the greater part of the carbonic acid which is exhaled, and for 

 the principal source of animal heat. I refer to the active meta- 

 morphosis of the blood, or to the mutual action excited by the 

 blood-corpuscles, the plasma, and the oxygen held in solution 

 in the blood, on each other. 



[I am indebted to the kindness of Dr. Percy for the following 

 analyses, which, to a certain amount, corroborate Simon's views. 



The urine of a man, aged 30 years, training for a pedestrian 

 match, was examined on two occasions : on the first, a quarter 

 of an hour after running a mile in five minutes and a few 

 seconds ; on the second, after running three races of one mile 

 each on the same day. 



In both cases the urine was of a pale straw colour ; it depo- 

 sited a slight mucous cloud on the first occasion, and was rather 

 more turbid on the second. It was acid, and its specific gravity 

 was 1019. It contained in 1000 parts : 



i. 2. 



Water 956-00 950-80 



Solid constituents 

 Urea 

 Uric acid 



Salts soluble in water 

 Salts insoluble in water 



44-00 49-20 



14-01 20-42 



1-58 -64 



11-16 7-88 



1-10 1-48 



Although the soluble salts are not increased as in the 

 cases of Lehmann and Simon, the augmentation of urea is very 

 striking.] 



To sum up once more : the urine is most abundant in urea, 

 uric acid, and the most important salts, in men in the prime of 

 life ; it is less rich in these constituents in women ; while the 

 minimum occurs in old men and children. The nature of the 

 food exerts an influence upon the composition of the urine : 

 the amount of urea is increased by an excess of nitrogenous 

 food, and diminished after living on food deficient in nitrogen. 

 Upon a diminution of the quantity of food, the urine becomes 

 deficient in nitrogen, as has been shown by my own experi- 



