8 S. SAGUCHI 



stained with acid fuchsin, iron-hematoxylin, etc. These ele- 

 ments are best brought into view by fixation with Zenker's fluid 

 and staining with Heidenhaiii's iron-hematoxylin. From these 

 reactions, it is obvious that osmic acid is not essential to the 

 preservation of the granules. Furthermore, acetic acid does not 

 dissolve them, but appears rather to favor their fixation. From 

 these properties, it is most probable that the granules are similar 

 with those which have been described by Laguesse and many 

 others; contrary to the view of Laguesse, Mankowski ('02), and 

 Tachassownikow ('06), who maintain that they are stained with 

 safranin, as is the case with chromatin, I have found that these 

 granules do not stain with alum-hematoxylin, but are, rather, 

 acidophilic and show a tingibility analogous to that of the nu- 

 cleolar and mitochondrial substance, differing only from the 

 latter in that the specific granules offer greater resistance to the 

 action of acetic acid. These granules, in part at least, seem to 

 have a certain affinity for silver salts, for in Cajal's preparations 

 they are stained a pale brown color, as has been pointed out by 

 Mankowski ('02) and Piazza ('11). 



The specific granules are of very minute size (figs. 1 to 3, b; 

 14 to 17) and they are so closely packed that it is almost impos- 

 sible to distinguish the individual granules; thus the protoplasm 

 exhibits, at first glance, a granular or powdery appearance, as 

 was first pointed out by Laguesse. Under these circumstances, 

 it is exceedingly difficult to decide whether or not this granula- 

 tion may be due to the interlacement of fine, tortuous filaments. 

 The granules, in the majority of cases, are distributed throughout 

 the whole cell-body, although not infrequently they are accumu- 

 lated in large numbers at one end of the cell. 



Most of the islets consist of cells which contain the specific 

 granules, and others which are either entirely devoid of them or 

 seem to contain only a very small number so that the protoplasm 

 is characterized by a hyaline, transparent appearance. These 

 two types of cells may be designated, respectively, as granular 

 and non-granular islet cells. The granular cells can further be 

 classified under three types according to the tingibility of the 

 granules, the shape and structure of the cell-body and of the 



