BILE IN THE HUMAN BODY. 167 



the liver into the circulation, and therefore will not 

 undergo the final changes dependant on the action 

 of oxygen ; or they will be separated by the kid- 

 neys in some form different from the normal one. 



71. In the preceding paragraphs I have endea- 

 voured to prove that the non-azotised constituents 

 of food exercise a most decided influence on the 

 nature and quality of the animal secretions. Whe- 

 ther this occur directly ; whether, that is to say, 

 their elements take an immediate share in the act 

 of transformation of tissues ; or whether their share 

 in that process be an indirect one, is a question 

 probably capable of being resolved by careful and 

 cautious experiment and observation. It is possible, 

 that the non-azotised constituents of food, after 

 undergoing some change, are carried from the intes- 

 tinal canal directly to the liver, and that they are 

 converted into bile in this organ, where they meet 

 with the products of the metamorphosed tissues, 

 and subsequently complete their course through the 

 circulation. 



This opinion appears more probable, when we 

 reflect that as yet no trace of starch or sugar has 

 been detected in arterial blood, not even in animals 

 which had been fed exclusively with these sub- 

 stances. We cannot ascribe to these substances, 

 since they are wanting in arterial blood, any share 

 in the nutritive process ; and the occurrence of 

 sugar in the urine of those affected with diabetes 

 mellitus (which sugar, according to the best obser- 



