250 W. J. M. SCOTT 



but the source of the material has been much debated. There 

 are several possible, though unlikely, sources of these lipoid 

 droplets which must be considered. Normal pancreases often 

 contain, in their acinus cells, small droplets of neutral fat and of 

 lipoid in variable ciuantities. I have studied their distribution by 

 staining with Sudan III and Scharlach R, after formalin fixation, 

 and by vitally staining with dilute solutions of nile blue B extra, 

 Meldola's blue (Sandoz, same as naphthol blue) and brilliant 

 cresyl blue. Fat of this sort does not stain with janus green. It 

 is also well known (Bensley '11, p. 363) that the mitochondria, 

 themselves, occasionally contain droplets of fat, though I have 

 searched diligently, but without success for traces of it in the 

 mitochondria of acinus cells of white mice. No relation could 

 be found between the formation of the lipoid droplets in the 

 poisoned pancreas and this neutral fat occurring free in the 

 cell or embedded in the filaments. 



Pieces of the pancreas, fixed in neutrjil formalin and bichro- 

 mate and stained in the routine manner with hematoxylin and 

 eosin show these droplets but do not indicate their source. The 

 whole process is made clear, how^ever, when sections prepared in 

 this way are stained by the fuchsin methyl green technique 

 which is here ad\'ocated. The mitochondria are brought to light 

 and the changes of agglutination (figs. 3 and 4) and of fusion 

 (figs. 4 and 5) to form the lipoid droplets, which they undergo, 

 are at once revealed. It seems that the mitochondria are the 

 actual source of the droplets. 



I wish to take this opportunity to express my appreciation 

 for the continuous advice and interest of Dr. E. V. Cowdry in 

 this research. 



CONCLUSIONS 



Mitochondria are the first constituents of the acinus cell of the 

 pancreas to show pathological change in phosphorus poisoning. 

 They lose their filamentous form, become shorter and thicker, 

 and their bleb-like swellings which are so characteristic of the 

 normal pancreas completely disappear (figs. 1 and 2). Then 



