LESSON XXIII. 



PANCREAS AND LIVER. 



A. PANCREAS. 



1. Section of pancreas of frog 1 (osmic acid, cut 

 frozen), mount in glycerine or in glycerine jelly. Ob- 

 serve 



(a) (1. p.), the lobules with their alveoli and ducts ; 

 the arrangement resembling in general features that of 

 the salivary glands : the ducts, however, have a larger 

 lumen, and cubical epithelium (cp. Lesson xx. 3). 



(6) (h. p.). The cells contain a number of separate, 

 spherical granules, on the inner or lumen side. How 

 far these stretch towards the outer limit of the cells 

 depends upon the state of digestion at the time the 

 animal was killed, but there will probably be a more or 

 less obvious outer non-granular zone. The outlines of 

 the cells and nuclei, as usual after osmic acid fixation, 



1 In mammals the granules are smaller than in the frog ; but the 

 pancreas of a mammal may be taken. 



