270 
George Arnold 
Description of Plate XII. 
The outlines of the drawings were sketched at the level of the stage, with a 
Zeiss drawing apparatus, 2 mm. 1,40. NA apochromatic immersion objektive Zeiss 
and compensating oculars 8 and 18 were used. Sections 7 u thick. All the illustra- 
tions are of cells of the pancreas of the guinea-pig. 
Figs. 3 and 13 drawn with 8 ocular and 2 mm. immersion, all the others with 
the 18 ocular and 2 mm. immersion. 
In order to reduce the number of stones in the lithographic reproduction, the blue 
colour of the thionin and methylcne blue stains has been represented throughout in 
black. 
Fig. 1. Alveolar cell. Fixation Zenker. Stain, iron-alum haematoxylin and 
orange G. The striation of the basal zone is sliown in yellow lines, in between wliicli 
can be seen the faint sliadowy r impressions of the cliondriokonts, in gre}\ 
Fig. 2. Alveolar cell. Fixation Flemming’s strong solution. Stain, saffranin- 
methylene blue and orange G. The basal zone contains small granules, similar to those 
in Fig. 13.swi; the longitudinal striation is faintly outlined in yellow. 
Fig. 3. Portion of an alveolus. Fixation Benda 1 ). Stain, saffranin-methylene 
blue and orange G., only the zymogen granules of the inner zone are stained by the 
saffianin. 
Fig. 4. Alveolar cell. Fixation Benda. Stain, Heidenhain’s iron-alum haema- 
toxylin, thionin and orange G. 
The beginning of the secretory pliase. Only a few zymogen granules have been 
formed. The cliondriokonts are numerous, and have attained their maximum di men- 
sions. Some show a beaded form at their proximal end, which indicates the commence- 
ment of the Separation of the pieces which will mature into zymogen granules. 
Fig. 5. Alveolar cell. Fixation and stain Altmann’s method. At about the 
same stage as Fig. 4. 
Fig. 6. Alveolar cell. Fixation Benda. Stain, Heidenhain’s iron-alum haema- 
toxylin, thionin and orange G. 
The middle of the secretory phase is sliown liere. The zymogen granules have 
increased in number, and the cliondriokonts are becoming tliinner. The beaded appear- 
ance is more general. Nucleus at its maximum volume. 
Fig. 7. Alveolar cell. Fixation and stain Altmann’s method. At about the 
same stage as Fig. 6. 
Fig. 8. Alveolar cell. Fixation Benda. Stain, Heidenhain’s iron-alum haema- 
toxylin, thionin and orange G. 
Cell between the end of the secretory and the beginning of the excretory phase. 
Inner zone full of zymogen granules, ready to pass out into the lumen of the alveolus. 
Cliondriokonts are verv thin, and their secretory activity at an end. The volume of the 
nucleus has diminished considerablv. 
Fig. 9. Alveolar cell. Fixation Benda. Stain, Heidenhain’s iron-alum haema- 
toxylin, thionin and orange G. 
In the rest phase. All the zymogen granules have been discharged, and the sub- 
stance of the cliondriokonts is exhausted. 
*) Benda’s modification of Flemming’s solution. 
