262 



PHYSIOLOGY AT THE FARM. 



Creatinine also to a small extent exists in the juice of flesh, 

 and along with creatine is found in the urine. 



The following table from Carpenter gives the composition 

 of these substances in relation to each other and to that of 

 albuminous compounds ; for each is given the number of com- 

 bining equivalents of its individual components, and the per- 

 centage proportion which the nitrogen bears to the whole. 



" Hence," says Dr Carpenter, " the proportion of nitrogen in 

 the components of urine ranges from double to triple that 

 which exists in the albuminous constituents of the living 

 fabric, the only exception being in the case of hippuric acid, 

 whose proportion of nitrogen is only one-half of that which 

 exists in albumen, whilst its percentage of carbon is triple 

 that which is contained in urea." * 



There are besides in the urine other substances, the nature 

 of which has not been as yet clearly determined. These are 

 commonly grouped together under the name of extractive 

 matters, and probably are in part at least non-azotised matters 

 in a state of change. 



There are also numerous inorganic or saline matters in the 

 urine, partly salts which are taken in as such in the food, 

 partly salts formed in the animal economy, the required acid 

 being supplied by the oxygenation of bases contained in the 

 aliment or derived from the disintegration of the animal solids, 



* Carpenter, ' Comparative Physiology,' p. 436. 



