14 S. SAGUCHI 



between the smallest and the largest granules which often reach 

 the diameter of a nucleus. In most cases they are evenly distrib- 

 uted throughout the protoplasm, but it not infrequently occurs 

 that they are accumulated near one end of the cell where the 

 latter is in contact with a blood-vessel. 



These lipoid corpuscles are present in b, d, and e cells, the larg- 

 est and greatest numbers being found in the last. They are 

 usually lacking or, if present, are few in number and of very small 

 size in a and c cells; the smallest can be manifested only by the 

 Golgi method. 



It should be mentioned in this connection that the lipoid cor- 

 puscles, in their physical and chemical properties, bear a strong 

 resemblance to the lipoid granules found in the basal portion of 

 the acinus cell, for the details of which the reader is referred to 

 my previous paper (Saguchi, '20). It may be that the two struc- 

 tures have the same functional significance, although in acinus 

 cells the production of the substance which constitutes them 

 does not take place to such a marked extent as in the islet cells. 



As regards their genesis, no definite conclusion can be reached 

 at present. It seems probable, however, taking into account 

 my previous observation that the lipoid granules in the acinus 

 cell are derived from mitochondrial filaments, that this is also 

 the case with the lipoid corpuscles in the islet cell. We have 

 seen that the mitochondrial granules in the e cells are formed by 

 the disintegration of the chondrioconts; it is possible to assume 

 that these granules, after having increased in size to a certain 

 extent, may change their physical and chemical properties and 

 become transformed into the smallest Upoid corpuscles, which 

 gradually increase in size, either by growth or by fusion. In 

 the same manner, the lipoid corpuscles of the h cells may be 

 regarded as derived from the specific granules or the granules of 

 mitochondrial nature which are contained in this type of cell. 



The problem as to the fate of the lipoid corpuscles is not a 

 simple one. The view of Dogiel ('93) that the islet must be 

 regarded as a dead spot, since it contains fat droplets which are 

 produced in consequence of the metamorphosis of the cell, is not 

 the correct one, for no degenerative process can be seen either in 



