THE PANCREATIC JUICE 711 



while excess of carbohydrate would cause an increase in the amylase of the 

 juice. Later researches have failed to confirm this view. Apparently when 

 the pancreas is excited to secrete, it turns out its various ferments in constant 

 proportion, depending on the amounts of these already present and stored 

 up in the gland. 



SECRETION OF PANCREATIC JUICE (WALTHER) 



THE STRUCTURAL CHANGES IN THE PANCREAS WHICH 



ACCOMPANY SECRETION 



The ease with which secretin may be prepared and used to arouse the 

 activity of the pancreas has rendered it possible to study more closely the 

 changes which in this gland accompany activity. Kiihne and Sheridan 

 Lea succeeded in observing the gland of the rabbit in a living state under the 



A B 



FIG. 340. A terminal lobule of the pancreas of the rabbit. (KiJHNE and 



SHERIDAN LEA.} 

 A, in resting condition ; B, after active secretion. 



microscope. They noted that activity, excited by pilocarpine, was associated 

 with a discharge of granules, a clearing up of the cells, and a diminution in 

 size and the appearance of a lumen to the gland alveoli (Fig. 340). A normal 

 resting gland is of an opaque, yellowish- white colour, and of firm consistence. 

 On section it is seen to consist of numerous secreting alveoli which open into 

 narrow intercalary tubules, and these in their turn into wide collecting 

 tubules. The lining epithelium of the intercalated tubules is often con- 

 tinued into the secreting part, where they lie internal to the secreting cells, 

 as the so-called centro-acinar cells. The secreting cells themselves present 



