168 ORIGIN OF THE NITROGEN 



vations, is derived from the food) coupled with its 

 total absence in the blood of the same patients, ob- 

 viously proves that starch and sugar are not, as such, 

 taken into the circulation. 



72. The writings of physiologists contain many 

 proofs of the presence of certain constituents of the 

 bile in the blood of man in a state of health, al- 

 though their quantity can hardly be determined. 

 Indeed, it' we suppose 8^ lbs. (58,000 grs.) of blood 

 to pass through the liver every minute, and if from 

 this quantity of blood 2 drops of bile (3 grains to 

 the drop) are secreted, this would amount to Wooth 

 part of the weight of the blood, a proportion far too 

 small to be quantitatively ascertained by analysis. 



73. The greater part of the bile in the body of 

 the herbivora, and in that of man fed on mixed 

 food, appears from the preceding considerations to 

 be derived from the elements of the non-azotised 

 food. But its formation is impossible without the 

 addition of an azotised body, for the bile is a com- 

 pound of nitrogen. All varieties of bile yet exa- 

 mined yield, when subjected to dry distillation, 

 ammonia and other nitrogenised products. Taurine 

 and ammonia may easily be extracted from ox bile ; 

 and the only reason why we cannot positively prove 

 that the same products may be obtained from the 

 bile of other animals is this, that it is not easy to 

 procure, in the case of many of these animals, a 

 sufficient quantity of bile for the experiment. 



Now, whether the nitrogenised compound which 



