10 S. SAGUCHI 



or at most, very few. Most of these cells are cylindrical or py- 

 ramidal in shape, either straight or curved, the short, cylindrical 

 or polygonal cells being few in number. Usually the nucleus is 

 oval, though more or less spherical nuclei are never entirely ab- 

 sent. Ordinaril}^ its position is in the middle of the cell, but cells 

 in which the nucleus is situated near one end are also often met 

 with. According to the behavior of the- protoplasm and the 

 nucleus toward iron-hematoxyhn or acid fuchsin, the non-granu- 

 lar cells can be divided into two groups which will be designated 

 as d and e cells. The d cells (figs. 1, d, 20) are characterized by 

 the fact that their protoplasm has a greater affinity for the above- 

 mentioned dyes; either the whole or a part of the cell-body 

 may be heavily stained. The nuclear membrane is less smooth. 

 The intranuclear network is very apparent and the meshes are 

 closer, as is the case with the a cells. The nucleolus is very 

 small. 



The d cells are few in number as compared with the other type 

 of non-granular cells which constitute a large part of the islet 

 elements. The protoplasm of the e cells (figs. 1, 3, 4, e; 18, 19, 

 21) is transparent when stained with iron-hematoxyhn or acid 

 fuchsin, which, in fact, is responsible for the clear appearance of 

 the islet in general. The nucleus has an even contour and con- 

 tains one or two small nucleoli and several nucleolar corpuscles 

 suspended in the indistinct nuclear net. Large nucleoli such as 

 are seen in acinus cells were never observed here. The nuclei 

 of the cells are similar to those of b cells in form, contour, and 

 character of the intranuclear network, differing from them only 

 in their heavily staining nucleolar corpuscles. 



Although, on the whole, the elements constituting the islets of 

 the pancreas fall into five groups mentioned above, there are 

 some cells which do not belong to any of these types, but which 

 possess the combined characteristics of any two of them and 

 must therefore be regarded as intermediate or transitional forms. 

 These forms will be described when relation between the types of 

 islet cells comes under consideration. 



As noted above, the nuclei of the islet cells are, in general, of 

 oval form, though the more spherical type is always represented. 



