XXIII.] 



THE PANCREAS. 



263 



not many ducts are visible. Curious groups of cells, "inter-tubular 

 cell clumps," each supplied by a glomerulus-like tuft of capillaries, 

 lie in the interlobular septa or amongst the acini. The alveoli, 

 tubular or flask-shaped, with a very small lumen, consist of a base- 

 ment membrane lined by a single layer of columnar or pyramidal 

 cells, each showing two zones ; an outer zone nearly homogeneous, 

 and staining with logwood and some other dyes, and an inner zone 

 crowded with "granules." The spherical nucleus lies about the 

 middle of the cell. Sometimes sections of Pacinian corpuscles and 

 groups of nerve-cells are found in the pancreas. 



This gland, like other glands, should be examined in different 

 phases of physiological activity. One, the active state ("dis- 

 charged "), when the gland is removed from the body (rabbit) two 

 or three or four hours after a full meal ; and the other, the passive, 

 or better, the resting state ("charged" or "loaded"), when the 

 pancreas is not secreting actively, which can be secured by allowing 

 an animal to fast for fourteen hours (dog or rabbit). The human 

 pancreas is rarely satisfactory. 



Methods. (i.) One of the best methods of fixing the pancreas is 

 i per cent, osmic acid or Flemming's mixture (24 hours). It is 

 then to be thoroughly washed and hardened, first in 75 per cent., 

 and afterwards in absolute alcohol. In such a preparation the 

 " granules " are usually 

 well preserved, and they 

 stain deeply with saf- 

 ranin. 



(ii.) Apiece hardened 

 in absolute alcohol and 

 stained in bulk in borax- 

 carmine or Heidenhain's 

 logwood (p. 70), and 

 afterwards cut in paraf- 

 fin, shows well the 

 general arrangement. 



(iii.) Fix a small piece 

 in corrosive sublimate, 



and, after the Usual pro- FIG. 254. T.S. Pancreas, Dog. A. Acinus ; C. Capsule; 

 cautions, Stain the sec- D - Duct - Corrosive sublimate and picro-carmine, 

 . \ . . X 300. 



tions with picro-carmine. 



Mount the osmic acid sections in glycerine, and the stained ones 

 in Farrant's solution or balsam. 



8. Resting Pancreas. (a.) (L) Observe the capsule (thinner), 

 septa (thinner), lobes, and lobules, as in salivary glands. This 

 arrangement is well seen in the carmine specimen (fig. 254, C). 



(b.) (H) In the osmic acid preparation observe the alveoli (fig. 



