168 THE SECRETIONS: 



noticed in the alkaline sulphates and phosphates. The quan- 

 tities excreted in twenty-four hours not only varied in different 

 persons,, but also in the same persons at different times. From 

 my analyses, and those of Lehmann, it appears probable that 

 a connexion subsists between the quantity of urea and of the 

 sulphates, and possibly of the phosphates likewise ; that is to 

 say, the sulphates always increase with the urea, and vice versa. 

 I incline, therefore, to the opinion of Berzelius, that at least a 

 portion of the sulphates and phosphates owe their origin to the 

 oxidation of sulphur and phosphorus, previously associated with 

 protein which has become changed during the active metamor- 

 phosis of the blood. We do not, however, mean, in making 

 this statement, to deny that the salts are also supplied to the 

 blood by the food, and again separated by the kidneys. 



The five following results, of much importance in physiology, 

 have been deduced from the admirable researches of Lecanu : 



1 . The quantity of urea excreted by the same person during 

 equal periods is constant. 



2. The same is the case with respect to the uric acid. 



3. The quantities of urea and uric acid excreted by different 

 persons during equal periods are variable. 



4. The varying amounts of urea excreted during equal 

 periods by different persons, bear a relation to age and sex. 



5. The amount of fixed salts varies in different persons without 

 reference to age or sex. It also varies in the same person 

 during equal periods. 



An observation simultaneously made by Lehmann* and 

 myself, 2 appears to me of high physiological import. We 

 have ascertained that the amount of the urea, as well as of the 

 sulphates, is increased by strong bodily exercise. I produced 

 this state by taking such violent exercise for two hours that the 

 pulse continued for some time above 100. 



Further confirmation of the above observation is certainly 

 desirable. 



If, however, we might assume it as a general fact, it would 

 be an additional argument in favour of my view regarding the 

 formation of urea ; for it would then become still clearer that 

 the urea is not formed during the change which occurs in the 



1 See page 164. 2 See page 144. 



