360 S. SAGUCHI 



rapid action of potassium bichromate or sublimate, which restrain 

 acetic acid from destructive action. The diffusibility of acetic 

 acid, on the contrary, is great, so that it penetrates more quickly 

 and produces changes before other constituents of the fixative 

 could come to act. This is the reason why the products o£ adhe- 

 sion increase in number as we proceed toward the deeper portion 

 of the piece. 



On the other hand, there are cases in which the formation of 

 fibrillar structures cannot be ascribed to the shrinking effect of 

 the fixative alone. Marked differences in the structures above 

 mentioned are often observed in individual animals, so that, pre- 

 served in one and the same fixative, one exhibits no remarkable 

 change, whereas in the other the structures are formed in so 

 large number that almost all the cells contain them. In the 

 latter case, the structures can well be seen even in the osmic 

 acid fixing material, where they appear indistinctly striated or 

 even homogeneous (fig. 88). 



It happens also that certain granules, stained black by iron- 

 haematoxylin, are interposed among the fibrillae of the structures 

 in question (figs. 88, 105). If some of these granules, as often 

 occurs, are located in the center of the spherical body with con- 

 centric striation, an appearance of a centrosphere 1 with central 

 corpuscles is produced. That this is, however, not the case is 

 obvious from the fact that the granules are situated not only in 

 the centre, but also in the other parts, even outside of the body 

 (fig. 105), and also that the number of the bodies may be two 

 or over; the granules in question are, rather, to be regarded 

 partly as zymogen or lipoid granules, partly as mere precipitates 

 of osmium, as will be referred to later on. 



Historical and critical. Regarding the cytoplasmic structure of 

 the secretory cell, especially of the pancreatic cell, there is wide 

 divergence of opinion among various investigators. 



1. Homogeneity of the protoplasm. As early as 1869 Langer- 

 hans described that the basal portion of the- pancreas cell in 

 fresh state, is entirely homogeneous. Later observations of R. 

 Heidenhain ('80), in fresh materials, and of Mouret ('95), in pre- 

 served cells, confirmed this. Hoven recently ('10) likewise 



