GLANDULAR CELLS OF THE FROG'S PANCREAS 353 



It is a difficult matter to determine definitely the significance 

 of the argentophile granules. They are, in all probability, prod- 

 ucts of the metabolism going on within the nucleolus, which 

 are to be eliminated from the latter and are to reach the cyto- 

 plasm in the manner above mentioned. It is quite within the 

 bounds of possibility that they are associated in some way with 

 the functional activity of the cytoplasm or they are, as waste 

 matters, to be cast off from the cell. Of these two possibilities 

 I am inclined to believe that the first one is more probable, since 

 the argentophile granules are often produced in considerable num- 

 ber in some alveolar cells of the pancreas which are undergoing 

 a certain change of functional activity, with which I shall have 

 occasion to deal at another time. 



The structure of the nucleolus in the egg-cells of several inver- 

 tebrates and lower vertebrates has been a problem for various 

 investigators ; some believe to have found a reticulation or vacuo- 

 lation of the nucleolus; others granules in it, which are known 

 under the name of 'nucleolini.' These structures can be mor- 

 phologically identified either with the argentophile granules or 

 with the negative of them, as I have seen. That the granules in 

 the nucleolus can be made manifest by the Cajal's photographic 

 method is not novel; Lache ('06) Cajal ('09), and others have 

 found the similar granules impregnated in the nucleolus of the 

 nerve cells; moreover, Lache's figure 1, which is drawn from a 

 Cajal preparation, shows that the same granules are in the nuclear 

 sap outside the nucleolus. In the pancreas literature I find in this 

 connection only the paper of Calier ('96) who suggested the ex- 

 istence of the nucleolini in the pancreas cell of the hedgehog and 

 gave the name of 'endonucleolus.' 



b. Side-nucleolus. Some of the nuclei of the pancreatic cells 

 have, besides the main-nucleolus just spoken of, one or two side- 

 nucleoli (figs. 2, 5, 6, 8, 16, 21). It seems, however, that they 

 are lacking in many of the nuclei. The side-nucleoli are of vari- 

 ous sizes; but even the largest one seldom exceeding one-third 

 of the diameter of the main-nucleolus. They are spherical cor- 

 puscles with an even contour, and bear a remarkable resemblance 

 in their staining reactions to the main-nucleolus, though, in some 



