DIGESTION 



319 



it will be best to omit for the present any detailed reference 

 to the liver, since, although there are histological marks of 

 secretive activity in this gland as well as in others, and of 

 the same general character, they are accompanied, and to 

 some extent overlaid, by the microscopic evidences of other 

 functions (p. 446). The serous salivary glands and the 

 pancreas can be taken together ; so can the cardiac and 

 pyloric glands of the stomach ; the mucous salivary glands 

 must be considered separately. 



Changes in the Pancreas and Parotid during Secretion, The 

 cells of the alveoli of the pancreas or parotid during rest, as 

 can be seen by examining thin lobules of the former between 



FIG. 103. SEROUS GLANDS IN 'LOADED* AND 'DISCHARGED' STATE. 



A, rabbit's pancreas, ' loaded" (resting) ; A', ' discharged' (active), observed in the 

 /ing animal (Kiihne and Lea). B*, loaded, B', discharged, alveolus of parotid (fresh 

 ;parations), (Langley). 



the folds of the mesentery in the living rabbit, or fresh 

 teased preparations of the latter, are filled with fine granules 

 to such an extent as to obscure the nucleus. In the parotid 

 the whole cell is granular, in the pancreas there is still a 

 larrow clear zone at the outer edge of the cell which 



>ntains few granules or none ; in both, the divisions 



jtween the cells are very indistinct, and the lumen of the 

 ilveolus cannot be made out. During activity the granules 



jem to be carried from the outer portion of the cell towards 

 lumen, and there discharged ; the clear outer zone of 

 :he pancreatic cell grows broader and broader at the 

 expense of the inner granular zone, until at last the latter 



lay in its turn be reduced to a narrow contour line around 



