DIGESTION OP POOD. 319 



and the stomach have been studied by a combination of histo- 

 logical and, more strictly, physiological methods, to which we 

 shall now refer. Specimens of these glands, both before and 

 after prolonged secretion, under stimulation of these nerves, 



Fig. 260.— Portion of pancreas of rabbit (after Eflhne and Lea). A represents gland 

 at rest; B, during secretion. 



were hardened, stained, and sections prepared. As was to be 

 expected, the results were not entirely satisfactory under these 

 ■methods ; however, the pancreas of a living rabbit has been 

 viewed with the microscope in its natural condition ; and by 

 this plan, especially when supplemented by the more involved 

 and artificial method first referred to, results have been reached 

 which may be ranked among the greatest triumphs of modern 

 physiology. 



Some of these we now proceed to state briefly. To begin 

 with the pancreas, it has been shown that, when the gland is 

 not secreting — i. e., not discharging its prepared flmd — or dur- 

 ing the so-called resting stage, the appearances are strikingly 

 different from what they are during activity. The cell pre- 

 sents during rest an inner granular zone and an outer clearer 

 zone, which stains more readily, and is relatively small in size. 

 The lumen of the alveolus is almost obliterated, and the in- 

 dividual cells very indistinct. -After a period of secreting 

 activity, the lumen is easily perceived, the granules have dis- 

 appeared in great part, the cells as a whole are smaller, and 

 have a clear appearance throughout. Coincident with the 

 changes in the gland's cells it is to be noticed that more blood 

 passes through it, owing to dilatation of the arterioles. 



Again, the course of the changes in the salivary glands, 

 whether of the mucous or serous variety, is very similar. In 



