198 



THE PANCREAS AT REST AND IN ACTION. [BOOK II. 



correspondingly narrower, and in some cases actually disappearing. The 

 whole cell is smaller, and owing to the relatively larger size of the 

 outer zone, stains well. The nucleus is spherical and well formed. If 

 the pancreas be examined at the end of digestion, when its activity has 

 once more ceased, and it has entered into a state of rest, the outer zone 

 is again found to be narrow, the granular inner zone occupying the 

 greater part of the cell, which in consequence stains with difficulty ; and 

 the whole cell has once more become larger. There seems to be but 

 one interpretation of these facts. During the time that the pancreas is 

 secreting most rapidly, there is a diminution of the inner zone ; that is 

 to say, the inner zone furnishes material for the secretion. But while 

 the inner zone is diminishing, the outer zone is increasing, that is to 

 say, the outer zone is being built up again out of materials brought to it 

 from the blood, though not to such an extent as to prevent the whole 

 cell from becoming smaller. When digestion is ended, after the pancreas 

 has ceased to secrete, the inner zone again enlarges, evidently at the 

 expense of the outer zone, though the latter also continues to increase, 

 causing the whole cell to become bigger. From thence till the next 

 meal, there occurs a partial consumption of the inner zone, so that the 

 outer zone becomes more conspicuous again, though the whole cell be- 

 comes smaller. Evidently out of the protoplasm of the cell, which is 

 itself formed at the expense of the blood, the granules are formed, and 

 these being deposited towards the lumen of the alveolus distinguish the 

 outer homogeneous from the inner granular zone, and the secretion is 

 produced at the expense of the granules. 



FlG. 14. A PORTION OF THE PANCREAS OF THE RABBIT (KiJHNE AND SHERIDAN L] 



A at rest, B in a state of activity. 



a the inner granular zone, which in A is larger, and more closely studded with fine 

 granules, than in B, in which the granules are fewer and coarser. 



b the outer transparent zone, small in A, larger in B, and in the latter marked with 

 faint strias. 



c the lumen, very obvious in J5, but indistinct in A. 



d an indentation at the junction of two cells, seen in B, but not occurring in A. 



1 Kiihne and Sheridan Lea 1 , observing, under the microscope, the pan- 

 creas of the living rabbit, have been able to watch the actual process of 



1 Verhandl. Naturhist. Med. Vereins, Heidelberg, Bd. i. (1877), Heft 5, and Bd. n. 

 (1882), Heft 4. 



