OF THE URINE. 301 



discharge it. For this purpose the urethra is given, 

 which varies with the sex, and will be farther consi- 

 dered in our account of the sexual functions. 



497. The bladder is evacuated from the constriction of 

 the sphincter being overcome both by the action of the 

 detrusor (495) and by the pressure of the abdomen. 

 To these in men is superadded the action of the acce- 

 leratores, which force out even the drops of urine re- 

 maining in the bulb of the urethra. 



498. The nature of the urine varies infinitely * from 

 age, season of the year, the length of the period since 

 food or drink was last taken, the quality of the ingesta,f 

 &c. The urine of an adult, recently made after a tran- 

 quil repose, is generally a watery fluid of a nidorous 

 smell and lemon colour, which qualities depend on a 

 peculiar uric substance, besides a variety of other 

 matters J held by the water in solution and differing in 

 their proportion in different persons. There is a re- 

 markable quantity of phosphoric acid united with other 

 constituents, forming phosphates of soda, ammonia, 

 and lime. A peculiar acid the lithic or uric, is found 

 in the urine only. (C) 



* See Halle", M&m. de la Soc. de Mtdec. Vol. iii. p. 469 sq. 



f The specific quality of some ingesta manifest themselves in the urine so 

 suddenly, even while blood drawn from a vein discovers no sign of their pre- 

 sence, that physiologists have thought there must be some secret ways leading 

 directly from the alimentary canal to the kidneys, besides the common channels. 

 See v. c. Griinaud, Sur la nutrition, p. 115. Darwin, Zoonomia. vol. i. 29. 

 and Home, Philos. Trans. 1808. (B) 



See Fr. Stromeyer, Theoret. chimie. p. 609. 



Consult on the analysis of the urine, among others, Berthollet, Mtm. de 

 FAcad. des Sc. de Paris. 1780. p. 10. 



Th. Lauth (praes, Spielmann), De analyst urine et acido phosphor ea. Argent. 

 1781. 4to. 



H. Fr. Link, 



