246 W. J. M. SCOTT 



cells are relatively scarce. The vacuoles range in size from 0.1^ 

 to 3/x in diameter. They have every appearance of being the 

 empty spaces left after neutral fat has been dissolved out. It 

 seems quite probable that this is the case for the chromatization 

 (eleven days at about 8°C.) would be quite insufficient to render 

 neutral fats insoluble. It is to be particularly noted that such a 

 cell contains the lipoidal droplets, and that its cytoplasm stains 

 deeply. A few mitochondria are still present in cells of this sort 

 visible between the vacuoles. This cell is of interest since 

 within it are shown the results of two processes, fatty infiltration, 

 and the formation of the lipoid droplets from mitochondria. 

 This great accumulation of neutral fat within the cell is not 

 associated in any demonstrable way with the formation of the 

 lipoid droplets, and is not a part of any stage of this process, as is 

 evidenced by the fact that only a few scattered cells show it and 

 that it is not a regular accompaniment of any stage in the aggluti- 

 nation or fusion of mitochondria. 



A very interesting condition, quite unlike any described above, 

 is observed in a number of the cells in the same sections from 

 which figures 5 and 6 were drawn. The whole cell is densely 

 packed with zymogen granules of varying sizes, which are 

 usually confined in the normal acinus cell, to the distal zone 

 (fig. 7). It is possible to distinguish clearly mitochondria as 

 brightly stained rods between the zymogen granules. These 

 mitochondria are short and thick and have no blebs. They 

 certainly do not seem to be increased in number; and, while it is 

 impossible to estimate their number exactly, because the zymo- 

 gen granules are so densely packed, the impression is gained 

 that they are somewhat diminished in number. The mito- 

 chondria and secretion granules can be clearly distinguished 

 here also by their difference in morphology and staining reaction : 

 the zymogen granules being always perfectly spherical and 

 staining an olive-brown to a purplish red (depending on the 

 differentiation), while the mitochondria are scarcely ever per- 

 fectly spherical and stain a brilliant crimson. Indeed it is 

 possible in all our preparations to distinguish between mito- 

 chondria and zymogen granules by their staining reaction in the 



