1912.] Islets of Langerhans to the Pancreatic Acini. 79 



The Exhausted Pancreas of the Guinea-Pig. 



Three exhaustion experiments were performed on guinea-pigs, in only 

 one of which could the animal be kept alive long enough to produce any 

 obvious exhaustion of the gland. This animal lived for six hours under 

 stimulation by secretin purified by the method of Stepp. The appearance 

 of the gland treated by the acid-fuchsin-methyl-green method differs in no 

 essential way from that of the dog, but under the neutral gentian stain the 

 islets are marked off with a distinctness which I have not been able to 

 obtain with a similar stain of the dog's pancreas. 



Figs. 3 and 4 show an islet with the surrounding tissue in a charged 

 gland and after exhaustion. By this method the zymogen granules of the 

 acinous cells are stained a deep lilac and the protoplasm a pale purple. No 

 mitochondrial elements are seen, and the centroacinous and duct cells 

 likewise fail to stain. 



In the islet of the charged gland the B cells are stained blue, the fine 

 uniform granules alone taking the colour. No mitochondrial elements are 

 to be seen. It therefore appears probable that the red rods and granules 

 which appear among the slate blue granules of the B cells of the acid-fuchsin 

 preparations are in reality mitochondrial in nature and not granular. The 

 A cells, or those which stain red with acid-fuchsin, fail here to take a 

 positive stain. They appear as faint yellowish to purple homogeneous masses 

 with an indistinguishable outline. 



In the exhausted gland the zymogen granules are greatly reduced. 

 Occasional small masses are present, especially close to the surface of a 

 lobule, but about the islet shown in fig. 4 (Plate 3) they have almost com- 

 pletely disappeared. The protoplasm of the acinous cell, however, takes the 

 same stain as in the charged organ, though it is often considerably vacuolated. 

 Among the acini a cell appears to which Bensley has called attention. 

 Several of these are shown in fig. 4 about the border of the islet, though 

 they are no less common in other parts of the lobule. This cell is filled 

 with perfectly round, uniform, purple granules, considerably smaller than 

 zymogen and distinctly larger than those of the islet. I have found cells 

 similar to these in specimens of discharged gland stained by acid-fuchsin. 

 Here the granular stain is uniformly red, but in addition the cell protoplasm 

 also takes a diffuse red stain. Such cells have a typical acinous arrange- 

 ment, and rarely one is found with some of the diffuse green colour of the 

 normal cell. I have not been able to find such cells in the acid-fuchsin 

 preparations of resting glands, but have found one or two in neutral gentian 

 stains of similar material. They resemble those which Bensley describes as 



