VI BILE 261 



Pancreatic juice, as containing these three ferments, 

 acts thei-efore on all three classes of foodstutFs, splitting 

 the proteins, saponifying and emulsifying the fats, and 

 converting starch into sugar. 



Although the most obvious function of the pancreas 

 is to secrete a digestive juice, there are reasons for 

 supposing that it has other important uses. If it be 

 removed from an animal, a large quantity of sugar 

 (dextrose) speedily appears in the urine and the animal 

 wastes away. Such a condition is not infrequently observed 

 in man, and is known as diabetes ; and in some cases 

 of diabetes the pancreas has been found to be diseased. 

 In this respect the pancreas seems to exert some control 

 over the nutrition of the body in a way somewhat 

 similar (though differing in its results) to the influence 

 exerted by the thyroid gland and the suprarenal bodies 

 (see pp. 217 and 219). This property of the pancreas is 

 associated with certain groups of cells known as the 

 Islets of Langerhans which diflfer in appearance from 

 the rest of tlie pancreas. 



15. The Nature and Action of Bile.— Bile is the 

 fluid secreted by the liver (see p. 213). In the con- 

 dition in which ifc may most ordinarily be observed it 

 has a greenish colour, but as it flows fresh from the 

 liver it is bright yellow with a brownish tinge. This 

 colour is due to a pigment called bilirubin. By 

 oxidation this may be easily converted into a green 

 pigment called biliverdin, and the differences in the 

 colour of the bile of different animals depends on the 

 relative amounts of these two pigments which they contain. 

 These colouring matters are usually known as the bile- 

 pigments, and of these the bilirubin is probably, as 

 already stated (p. 105), formed from the hfemoglobin of 

 the red blood-corpuscles by some peculiar action of the 

 cell-* of the liver. In addition to the pigments bile, which 

 consists of about 85 per cent, of water, holds in solution 

 certain salts of sodium, the bile-salts. These are salts 



