406 CHANGES IN PANCREATIC CELLS. [BOOK n. 



largely dilated and the stream of blood through the capillaries is 

 full and rapid. 



With care the change from the one state of things to the other 

 may be watched under the microscope. The vascular changes can 

 of course be easily appreciated, but the granules may also be seen 

 to diminish in number. Those at the inner margin seem to be 

 discharged into the lumen, and those nearer the outer margin 

 to travel inwards through the cell-substance towards the lumen, 

 the faint stria? spoken of above, apparently at all events, being the 

 marks of their paths. Obviously during secretion, the granules 

 with which the cell-substance was ' loaded ' are ' discharged ' from 

 the cell into the lumen of the alveolus. What changes these 

 granules may undergo during the discharge we shall consider 

 presently. 



Sections of the prepared and hardened pancreas of any animal 

 tell nearly the same tale as that thus told by the living pancreas 

 of the rabbit. In sections for instance of the pancreas of a dog 

 which has not been fed, and therefore has not been digesting, for 

 some hours (24 or 30), the cells are seen to be crowded with 

 granules (which however are usually shrunken and irregular owing 

 to the influence of the hardening agent), leaving a very narrow 

 outer zone. In similar sections of the pancreas of a dog which 

 has been recently fed, six hours before for example, and in which 

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

 granules are far less numerous, and the clear outer zone accordingly 

 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, hsematoxylin &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 



