416 Cytology of the Areas of Langerhans 



by the chrome-sublimate fluid, and the substance that is precipitated by 

 the chrome-sublimate fluid is dissolved by alcohol. 



3. Neither of these granular substances is of the same chemical char- 

 acter as the zymogen granules of the pancreas cell, and 



4. Neither of them is of the same chemical character as the prozy- 

 mogen of the pancreas cell. 



To avoid cumbersome periphrase and repetition I will hereafter desig- 

 nate the cells in which the granules are fixed with alcohol as A cells, and 

 these in which the granules are fixed with the chrome-sublimate fluid as 

 (3 cells. 



That the chemical nature of the granules in the A cells differs from 

 that of the granular content of the (3 cells is borne out by the difference 

 of the reaction of these substances to various fixing reagents non-alcoholic 

 in character, and for the most part very simple in composition. The 

 results follow : 



Saturated Aqueous Sublimate. With this fixation the islet cells act in 

 virtually the same manner as with aqueous-chrome-sublimate, with the 

 exception, that the tissues are rather shrunken than the reverse. The A 

 cells remain devoid of basic granules, the /? cells are very well preserved, 

 and, throughout the whole of their cytoplasm, they are crowded with the 

 violet granules, which are, however, not as brilliantly stained as in 

 preparations fixed with aqueous-chrome-sublimate. The zymogen granules 

 in the acini, on the contrary, are well fixed and react with a brilliant stain 

 to the neutral gentian. 



Saturated Picric Acid. This fixation is poor, in a general way, and 

 both types of islet cells are entirely devoid of granules, taking up only 

 the plasma stain. The zymogen granules, here also, are sharply defined 

 and stain well. 



Nitric Acid, 10 per cent. The general fixation is poor, but the acid 

 seeks the A cells much in the same way as does alcohol, and the granules 

 in them are well preserved. The (3 cells, with this fixation, remain clear 

 of granules altogether. So far as the A cells are concerned, the picture 

 here presented is substantially the same as that obtained with the use 

 of alcohol-chrome-sublimate and 70 per cent alcohol. 



Formal, 10 per cent. This fluid fixes the granules in the A cells, leaving 

 the f3 cells clear. Although the stain is by no means as brilliant as that 

 obtained with the three principal fluids, yet the individuality of the 

 granules in the A cells is capitally preserved. The zymogen granules in 

 the pancreas cells are broken down and diffused. 



Chromic Acid, 1 per cent. In this fixation the granules in the A and 



