450 



URINE. 



the influence which the different periods of life exert on the con- 

 stitution and the quantitative relations of the urine. It appears 

 generally from his observations, that men in the vigour of early adult 

 life, when the metamorphosis of tissue is proceeding most actively, 

 secrete the largest quantity of solid constituents with the urine ; 

 that women secrete somewhat less, and children and aged persons 

 still smaller quantities. The period of life appears to exert no 

 influence on the quantities of the uric acid and of the salts. From 

 certain experiments, it would appear that the urine of very young 

 children contains relatively more hippuric acid and far less phos- 

 phate of lime than the urine in more advanced life. 



Of all the physiological conditions, the food is unquestionably 

 that which exerts the most marked influence on the constitution 

 of the urine. We have already spoken, in various parts of this 

 work, of the influence which special substances contained in the 

 food exert on the acid or alkaline reaction of the urine, and on 

 some of its constituents. In the prolonged series of experiments, 

 to which I have often alluded, I have attempted to ascertain the 

 influence which varieties of diet (animal, vegetable, and non- 

 nitrogenous) exert on the character of the urine generally, and 

 on its special quantitative relations. The most essential results 

 may be seen at a glance in the following tabular arrangement. 

 While living on a mixed diet and adhering as closely as possible 

 to the same dietetic conditions, I made the analysis of the collected 

 urine; while living on a purely animal diet (almost exclusively on 

 eggs), I made twelve observations, and a similar number while 

 living on a purely vegetable diet; and while living on perfectly 

 non- nitrogenous food (fat, milk-sugar, and starch) I made two 

 analyses ; and, independently of the variable quantities of water, the 

 following were the mean quantities (in grammes) of the other sub- 

 stances which were discharged in the twenty-four hours' urine: 



From these researches we may draw the following general con- 

 clusions : 



(1.) The solid constituents of the urine are very much increased 



