THE CONQUEST OF DISEASE 



liver were never known until studied by animal 

 experimentation. Concerning the pancreas, 

 researches have been going on since 1664 when 

 de Graaf made a fistula on a dog and studied 

 the pancreatic secretion. Now a vast literature 

 is required to contain what has been learned 

 of it. The researches of Mering and Minkow- 

 ski are triumphs of scientific method. Its 

 diastatic action upon starches and sugars, its 

 tryptic action upon proteids, its fat-splitting 

 and fat-emulsifying action, and its milk curd- 

 ling function, have all been followed out to an 

 almost ultimate degree. 



Studies of the pancreas have shown that 

 this organ has important functions besides the 

 secretion of its digestive juice. If the pan- 

 creatic duct is made to empty its secretion 

 through a fistula outside of the body the 

 animal does not die; but if the pancreas is re- 

 moved and pancreatic juice is supplied to the 

 intestine from another source the animal does 

 die. The animal lives if the gland is removed 

 and then implanted under the skin in some 

 other part of the body. The substances which 

 the pancreas supplies to the blood are essen- 

 tial to life. These substances have to do with 

 the metabolism of sugar. When, as a result of 



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