64 HORSE.BACK RIDING. 



combustion of the azotic substances, while the urea is 

 the product of incomplete combustion, as the uric 

 acid which always diminishes by exercise and increases 

 from inaction. These phenomena are, indeed, in per- 

 fect ratio to the activity of the internal combustion, of 

 which they are but the consequence. 



The excitement of the muscular fibre of the bladder 

 by the shocks resulting of the motion of the horse 

 causes its contraction, and if it contains a certain quan- 

 tity of fluid, the desire for micturition soon makes itself 

 felt. Horse-back riding provokes it."" 



* De I'equitation. Chassaigne. Paris, 1870. 



