67 



portion of albumen to the bile; but as the matter 

 which they have here called albumen is precipi- 

 tated from the bile by acetic acid, and cannot 

 be dissolved in an excess of acid, it must, of 

 course, be something else. In an examination 

 of the mucus from different parts of the mucous 

 membranes, I demonstrated * that this matter is 

 nothing 1 else, than a part of the mucus of the gall- 

 bladder, which has become dissolved in the bile, 

 and made it what physicians term, more in- 

 volved. The bile, however, contains it in very 

 small quantities ; for when this fluid is very thick 

 it does not afford a perceptibly greater residuum 

 after evaporation, thani when it is quite thin. 



This is'all that we know of those fluids, which 

 have any thing to do with digestion ; and although 

 this process is more independent of the immediate 

 influence of the .nervous system than most others* 

 it is far from being sufficiently understood. It was 

 for a long time believed that the office of the sto- 

 mach, in digestion, was nothing elso than a me* 

 chanical effect of its membranes, in triturating the 

 food. The experiments, however, of STEVENS, 

 REAUMUR, and SPALLANZ ANI, have proved the 

 incorrectness of this supposition. They caused 

 animals to swallow tubes, and balls, of metal, per- 



F 2 



