16 S. SAGUCHI 



granules nor filaments pass into the vacuoles which correspond 

 to the dissolved out lipoid corpuscles. 



As regards the distribution of urano-argentophile granules 

 and filaments in islet cells, it can be said that cells containing 

 granules in association with filaments are rarely seen; conse- 

 quently, cells containing granules are usually devoid of filaments, 

 or at the most, contain short, thick rods. By far the largest 

 number of islet cells are of the latter type; these cells are cylin- 

 drical in shape and are in contact with blood-vessels at one or 

 both ends. They also contain a great number of spherical vacu- 

 oles corresponding to Hpoid corpuscles (figs. 6, e, 29, 30). On the 

 other hand, there are cells which are provided wdth granular urano- 

 argentophile corpuscles, but in these the vacuoles are not evi- 

 dent; the cells of this type usually occur in small groups between 

 acinus cells. 



The cells containing urano-argentophile filaments can be sub- 

 divided into three kinds according to size, shape, and position. 

 In the first place, there are some cylindrical cells which occur in 

 the peripheral part of the islet or are interspersed between acinus 

 cells, and which are laden with a large number of either thin or 

 thick filaments. They have, in most cases, spherical nuclei 

 which are usually situated near one end of the cell (figs. 25 to 27) . 

 The second type of cell is small, and often long, narrow, and 

 cylindrical in form. It is always situated at the periphery of the 

 islet and contains a small number of filaments (fig. 32). The 

 third tA^pe is situated between the cells containing urano-argen- 

 tophile granules; its protoplasm stains more or less deeply and 

 possesses a few tortuous filaments. It is characteristic of this 

 kind of cell that the vacuoles corresponding to the lipoid cor- 

 puscles appear to be lacking, at least no larger ones are visible 

 (fig. 33). 



The question now arises, how can we identify these five types 

 of cells with the a, b, c, d, and e cells. This is an exceedingly dif- 

 ficult problem, since we possess at present no technical methods 

 by which to bring into view both specific granules and urano- 

 argentophile corpuscles in one and the same preparation. The 

 presence of large numbers of both lipoid corpuscles and urano- 



