144 The Life Story of the Fish 



The liver is large, taking up a disproportionate amount of 

 the body cavity. The gall-bladder and the spleen are clearly 

 recognizable, but the pancreas is what is called "diffuse," 

 which means that it is pretty well scattered about. It does 



Figure 20. LOWER INTESTINE OF THE SHARK CUT OPEN TO 

 SHOV^ THE SPIRAL VALVE 



From J. R. Norman, History of Fishes. 



nevertheless contain something in the nature of the "islets of 

 Langerhans" (the name given to the ductless glands in the 

 mammalian pancreas from which insulin is obtained) for 

 the discovery has been made that insulin can be obtained 

 from fish pancreas. If this proves to be commercially prac- 

 tical, diabetics can look forward to an unlimited supply of 

 this indispensable remedy at a low price. 



