NOXIOUS MATTERS REMOVED BY THE URINE. 265 



amount excreted by adult males is about 430 grains by adult 

 females, about 300 grains ; in children of eight years old it is 

 nearly half what it is in adults, whilst in very old persons the 

 quantity sinks to one third or even less, showing that the 

 proportion is greatly influenced by the rapidity of interstitial 

 change at different periods of life. There can be no doubt 

 that creatine and creatinine have the same origin and character, 

 since they are actually found in the juice of flesh as well as in 

 the urine. So the proportion of alkaline phosphates in the 

 urine is found to bear such a close relation to the previous 

 energy of the nervous system that there can be little doubt 

 that, cceteris paribus, their amount may be taken as a measure 

 of its disintegration by functional activity. It has been 

 pointed out that for the maintenance of this activity a con- 

 stant supply of arterialised blood is a necessary condition ; 

 and whilst the other elements of the nervous tissue (whose 

 composition is almost entirely adipose) will be carried off by 

 oxygenation in the form of carbonic acid and water, the phos- 

 phorus which largely enters into it will be oxygenated and 

 taken back into the blood in the form of phosphoric acid, 

 uniting there with alkaline bases, as already explained. The 

 portion of extractive matters appears chiefly to depend upon 

 the nature of the food ; being greatly augmented by an exclu- 

 sively vegetable regimen, and greatly diminished by an exclu- 

 sively animal diet. The importance of the urinary secretion 

 in removing superfluous or injurious saline compounds from 

 the system (the introduction of which into it has taken place 

 by endosmotic action) is further shown by the increase in the 

 secretion which most of these substances produce ; this increase 

 being the result of an augmented determination of blood to 

 the kidneys, and a consequently increased transudation of its 

 watery portion carrying these substances with it." * 



* Carpenter, * Comparative Physiology, ' pp. 436,437. 



