THE PANCREATIC JUICE 799 



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 Lee succeeded in observing the gland of the rabbit in 



FIG. 338. A terminal lobule of the pancreas of the rabbit. (KtJHNE and 



SHERIDAN LEA.) 

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



a living state under the 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. 338). 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 < 



