OF ANIMALS. 453 



somewhat stronger acid reaction, than that which is passed during 

 the day. The quantities of this morning urine vary with the 

 amount of drink that has been taken before retiring to rest. Inde- 

 pendently of the smaller quantity of water which it contains, I can 

 detect no difference in the ratio of its constituents to one another. 

 The nature of the food exerts a certain amount of influence on the 

 morning urine ; at all events, while living on animal food, I found 

 it comparatively even more concentrated than the urine passed 

 during the day ; even after living for only a single day on purely 

 animal food, I found that on the addition of nitric acid to the 

 urine passed on the following morning, nitrate of urea was at once 

 separated. 



Another kind of urine, that, namely, of digestion, or the urina 

 chyli, was formerly regarded as a distinct variety, to which much 

 weight was attached ; in those who do not drink much at, or after, 

 their meals, it is somewhat denser and more coloured than that 

 which is passed at other periods of the day ; it is, however, not so 

 coloured or so dense as the morning urine. 



Chambert's experiments, which appear to have been very care- 

 fully conducted, do not altogether coincide with my own: the 

 differences are, however, such as may be readily explained by sur- 

 rounding circumstances. Chambert invariably found the urine of 

 digestion denser and richer in salts than the morning urine; the 

 greater or lesser transpiration during sleep, and the varying 

 amount of drink taken at meal-time, afford the simplest clue to 

 these differences. Moreover, Chambert found that the inorganic 

 constituents of the urine stand in a direct proportion to the 

 quantity of the salts taken in the food. 



In the twenty-four hours' urine Chambert found on an average 

 1-30242 of salts, in the urine of digestion 1'6394-g-, and in the 

 urine discharged between waking and breakfast 0'9332-g-, while in 

 the urine soon after drink had been taken, the maximum was 

 only 0'2113. 



In animals, at all events, in the mammalia, the influence of 

 the food is reflected in the constitution of the urine. We will 

 now proceed to notice the urine of animals, classifying them 

 according to the nature of their food. 



Unfortunately, our knowledge of the urine of the omnivora is 

 confined to that of the man and the pig. The urine of the latter 

 animal has been examined by Boussingault* and von Bibraf; 

 it is perfectly clear, almost devoid of odour, distinctly alkaline, 

 * Ann. de Chim. et de Phys. 3 Se'r., T. 15, p. 97104 

 t Ann. d. Ch. u. Pharm. Bd. 53, S. 98112. 



