THE PANCREATIC JUICE 



757 



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 oat 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 

 ACCOMPANYING 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 



Fia. 352. 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 asso- 

 ciated with a discharge of granules, a clearing up of the cells, and a diminu- 

 tion in size and the appearance of a lumen to the gland alveoli (Fig. 352). 

 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 continued into the secreting part, where they lie internal to the secret- 

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



