CH. XXXII.] 



THE PANCREAS. 



487 



called trypsinogen ; that is, the precursor of trypsin, the most 

 important ferment of the pancreatic juice. 



- 



lte '* 



Fig. 400. Section of the pancreas of armadillo, showing alveoli and an islet of epithelium 

 in the connective tissue. (V. D. Harris.) 



In the centre of the acini, spindle-shaped cells (centro-acinar 

 cells) are often seen ; their function and origin are unknown. 



Composition and Action of Pancreatic Juice. 



The pancreatic juice may be obtained by a fistula in animals, 

 a cannula being inserted into the main pancreatic duct ; but as 

 in the case of gastric juice, experiments on the pancreatic secretion 

 are usually performed with an artificial juice made by mixing a weak 

 alkaline solution (i per cent, sodium carbonate) with a glycerin 

 extract of pancreas. The pancreas should be treated with dilute 

 acid for a few hours before the glycerin is added. This ensures 

 a conversion of the trypsinogen into trypsin. 



Quantitative analysis of human pancreatic juice gives the 

 following results : 



Water . . . 97-6 per cent. 



Organic solids . . i '8 



Inorganic salts . 0*6 ,, 



In the dog the amount of solids is much greater. 

 The organic substances in pancreatic juice are 

 (a) Ferments. These are the most important both quantita- 

 tively and functionally. They are four in number : 

 i. Trypsin, a proteolytic ferment. 



ii. Amylopsin or pancreatic diastase, an amylolytic ferment, 

 iii. Steapsin, a fat-splitting or lipolytic ferment, 

 iv. A milk-curdling ferment. 



