1044 SECRETED FLUIDS SUBSERVIENT TO DIGESTION. 



ash, of which chloride of potassium is the most considerable, 

 and a peculiar animal substance, which is named salivary matter. 

 The latter is soluble in water, not coagulated by boiling nor 

 precipitated by metallic salts. In the salivary glands and ducts 

 of the horse and ass, concretions are sometimes found, which 

 are principally composed of carbonate and a little phosphate of 

 lime. The saliva of man and the sheep generally contains a 

 trace of sulphocyanide of potassium; the saliva of the sheep 

 contains also so much carbonate of soda as to eifervesce with an 

 acid. 



Gastric juice. The principal constituent of this fluid is the 

 peculiar principle, pepsin (page 1030). When collected from 

 the stomach during fasting, it is a transparent fluid, of a saline 

 taste, which is neutral, but during the process of digestion 

 it is distinctly acid from the presence of hydrochloric acid. 



Pancreatic juice. This fluid, secreted in the pancreas, is 

 thrown into the duodenum, or the portion of the small intes- 

 tines nearest the stomach, where it mixes with the partially 

 digested food or chyme, as the latter leaves the stomach. It 

 contains albumen in solution and also a matter like casein ; its 

 salts are nearly the same as those of the saliva ; it has a distinct 

 acid re-action. The uses of this fluid in digestion are un- 

 known. 



BILE AND BILIARY CONCRETIONS. 



The bile which is contained in the gall-bladder is conveyed to 

 the duodenum and added to the chyme in digestion. It is-a 

 greenish yellow fluid, of a peculiar sickening odour, and taste 

 which is at first sweet, but afterwards bitter and exceedingly 

 nauseous. It contains a great variety of substances, of which 

 the most peculiar, which are all in a state of true solution, are 

 bilin, fellinic acid, cholinic acid and biliverdin, according to the 

 latest examination of this secretion, by Berzelius. Besides the 

 acids mentioned, it contains oily acids combined in common 

 with the others with soda, and several other fatty bodies, 

 together with cholesterin. To which are to be added mucus, 

 an undetermined animal matter, common salt, and the other 

 usual salts of animal fluids. The separation of so many sub- 

 stances is extremely difficult, and the more so that the consti- 



