THE PANCREAS. 



299 



a homogeneous protoplasm, while those parts of the cells border- 

 ing upon the lumen are granular. The relation of these zones to 



Nucleus and 

 outer zone. 



Fig. 239. Transverse section through alveolus of frog's pancreas. 



each other depends upon the physiologic condition of the gland ; 

 during starvation the internal or granular zone is wide and promi- 

 nent ; after moderate secretion the cells become as a whole some- 

 what smaller, the granules decrease in number, and the outer or 

 protoplasmic zone increases in size. After prolonged secretion 

 there is an entire absence of the granules, and the whole cell appar- 

 ently consists of homogeneous protoplasm. It is therefore probable 



Fig. 240. Model of lobule of human pancreas (Maziarski, " Anatomische Hefte," 



1901). 



that during a state of rest peculiar granules (zymogen granules) are 

 formed at the expense of the protoplasm, and that these granules 

 represent a preliminary stage of the finished secretion. During the 



