ORGANIC REMEDIAL AGENTS. 175 



of the living body, or in the production of certain 

 secretions. 



81. The vital process of secretion, in so far as it 

 is related to the chemical forces, has been subjected 

 to examination in the preceding pages. In the car- 

 nivora we have reason to believe, that, without the 

 addition of any foreign matter in the food, the bile 

 and the constituents of the urine are formed in 

 those parts where the change of matter takes place. 

 In other classes of animals, on the other hand, we 

 may suppose that in the organ of secretion itself, 

 the secreted fluid is produced from certain matters 

 conveyed to it ; in the herbivora, for example, the 

 bile is formed from the elements of starch along 

 with those of a nitrogenised product of the meta- 

 morphosis of the tissues. But this supposition by 

 no means excludes the opinion, that in the carni- 

 vora the products of the metamorphosed tissues are 

 resolved into bile, uric acid, or urea, only after reach- 

 ing the secreting organ ; nor the opinion that the 

 elements of the non-azotise^ food, conveyed directly 

 by the circulation to every part of the body, where 

 change of matter is going on, may there unite with 

 the elements of the metamorphosed tissues," to form 

 the constituents of the bile and of the urine. 



82. If we now assume, that certain medicinal 

 agents may become constituents of secretions, this 

 can only occur in two ways. Either they enter the 

 circulation, and take a direct share in the change of 

 matter, in so far as their elements enter into the 



