342 CHANGES IX PANCREATIC CELLS. [BOOK n 



therefore the gland has been for some time actively secreting, the 

 granules are far less numerous, and the clear outer zone accord- 

 ingly much broader and more conspicuous. With osmic acid these 

 granules stain well, and are preserved in their spherical form, so 

 that the cell thus stained maintains much of the appearance of a 

 living cell. But with carmine, heematoxylin &c. the granules do 

 not stain nearly so readily as does the cell-substance of the cells, 

 so that a discharged cell stains more deeply than does a loaded cell 

 because the staining of the ' protoplasmic ' cell-substance is not so 

 much obscured by the unstained granules ; besides which however 

 the actual cell-substance stains probably somewhat more deeply 

 in the discharged cell. It may be added that in the discharged 

 cell the nucleus is conspicuous and well formed ; in the loaded cell 

 it is generally in prepared sections, more or less irregular, possibly 

 because in these it is less dense and more watery than in the dis- 

 charged cell, and so shrinks under the influence of the reagents 

 employed. 



These several observations suggest the conclusion that in a 

 gland at rest the cell is occupied in forming by means of the 

 metabolism of its cell-substance and lodging in itself ( 30) 

 certain granules of peculiar substance intended to be a part and 

 probably an important part of the secretion. This goes on until 

 the cell is more or less completely ' loaded.' In such a cell the 

 amount of actual living cell-substance is relatively small, its place 

 is largely occupied by granules, and it itself has been partly 

 consumed in forming the granules. During ,the act of secretion 

 the granules are discharged to form part of the secretion, other 

 matters including water, as we shall see, making up the whole 

 secretion ; and the cell would be proportionately reduced in size 

 were it not that the act of the discharge seems to stimulate the cell- 

 substance to a new activity of growth, so that new cell-substance 

 is formed; this however is in turn soon in part consumed in 

 order to form new granules. And what is thus seen with con- 

 siderable distinctness and ease in the pancreas, is seen with more 

 or less distinctness in other glands. 



196. When we study an ' albuminous/ or ' serous ' salivary 

 gland, the parotid gland for instance, in a living state, we find 

 that the changes which take place during activity are quite 

 comparable to those of the pancreas. During rest (Fig. 78 A), 

 the cells are large, their outlines very indistinct, in fact almost 

 invisible, and the cell-substance is studded with granules. Dur- 

 ing activity (Fig. 78 B), the cells become smaller, their outlines 

 more distinct, and the granules disappear, especially from the 

 outer portions of each cell. After prolonged activity, as in 

 Fig. 78 C, the cells are still smaller with their outlines still more 

 distinct, and the granules have disappeared almost entirely, a few 

 only being left at the extreme inner margin of each cell, abutting 

 upon the conspicuous, almost gaping lumen of the alveolus. And 



