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Dr. J. Homans. The Relation of the 



[Oct. 1, 



The nuclei of the various cells present less characteristic differences than 

 do the granules. Those of the acinous cells do not always show a bright 

 red nucleolus. On the other hand, the chromatin which they contain 

 is often arranged like that in the islet nuclei. Moreover, the islet nuclei 

 may often contain what appears to be a typical nucleolus. Accordingly, 

 for purposes of differentiation, I have given little attention to the nuclei of 

 the different cells. 



I shall describe the appearance of islet tissue stained with neutral 

 gentian in connection with pancreas exhaustion experiments in the guinea- 

 pig. In the dog, neutral gentian, though it stains beautifully the zymogen 

 granules, has proved rather unsatisfactory for the islet granules. In the 

 guinea-pig, on the other hand, it gives the most striking pictures. 



The Exhausted Pancreas of the Dog. 



Of the two exhaustion experiments performed on the dog only one was 

 completely successful. In this the flow of pancreatic juice was very free, 

 about 210 c.c. being secreted in the course of nine hours. At the end of 

 this time, though the flow had not ceased, the pancreas appeared rosy and 

 translucent in contrast to the opaque appearance of the small segment tied 

 off for comparison. 



Examination of the discharged organ (fig. 2, Plate 2) shows the exhaustion 

 to be fairly complete. There is no evidence of any transition of acinous to 

 islet tissue. The acinous cells have for the most part lost their zymogen 

 granules. In consequence, the mitochondrial filaments appear more prominent 

 than usual, but the protoplasm of the cells, though somewhat vacuolated, 

 still takes the characteristic smooth green stain. 



The islet shown in the figure is well charged with granules. Whether 

 the gathering of these granules along the capillaries is an effect of secretin 

 stimulation I do not know, but as most of the islets do not present this 

 appearance, and as it has been noted in the resting gland, I believe that it 

 is accidental. The most noteworthy change in the relation of the islet to 

 the surrounding acinous tissue is that the exhaustion of the zymogen in the 

 surrounding pancreas causes the islet to appear more sharply marked off 

 than usual. This is in strong contrast to preparations of the same organ 

 fixed in Zenker's fluid, and stained with eosin and toluidine blue, when the 

 islets, being merely negatively stained, can be distinguished with some 

 difficulty from the more exhausted portions of the acinous tissue. 



