ORGANS AND PROCESSES OF DIGESTION 155 



The Bile is a golden yellow liquid, having a slightly 

 alkaline reaction and a very bitter taste. It consists, on 

 the average, of about 97 per cent of water and 3 per cent 

 of solids. 1 The solids include bile pigments, bile salts, a 

 substance called cholesterine, and mineral salts. The 

 pigments (coloring matter) of the bile are derived from the 

 hemoglobin of broken-down red corpuscles (page 27). 



Much about the composition of the bile is not under- 

 stood. It is known, however, to be necessary to digestion, 

 its chief use being to aid in the digestion and absorption of 

 fats. It is claimed also that the bile aids the digestive pro- 

 cesses in some general ways counteracting the acid of 

 the gastric juice, preventing the decomposition of food 

 in the intestines, and stimulating muscular action in the 

 intestinal walls; No enzymes have been discovered in 

 the bile. 



The Pancreas is a tapering and somewhat wedge-shaped 

 gland, and is so situated that its larger extremity, or head, 

 is encircled by the duodenum. From here the more 

 slender portion extends across the abdominal cavity nearly 

 parallel to and behind the lower part of the stomach. It 

 has a length of six or eight inches and weighs from two 

 to three and one half ounces. Its secretion, the pancreatic 

 juice, is emptied into the duodenum by a duct which, as a 

 rule, unites with the duct from the liver. 



The Pancreatic Juice is a colorless and rather viscid 

 liquid, having an alkaline reaction. It consists of about 

 97.6 per cent of water and 2.4 per cent of solids. The 

 solids include mineral salts (the chief of which is sodium 

 carbonate) and four different chemical agents, or enzymes, 

 trypsin, amylopsin, steapsin, and a milk-curding enzyme. 

 These active constituents make of the pancreatic juice the 



1 Hammerstein, Text-book of Physiological Chemistry. 



