286 ROYAL SOCIETY OF CANADA 
EXPLANATION OF THE PLATES. 
Lettering common to all the figures. 
ad. = adenoid tissue. 
bld. c. = red blood corpuscles. 
cap. = blood capillaries. 
a —s0uct: 
i. = islet of Langerhans. 
1. = lumen. 
trans. c. = transitional cells. 
Zym. zymogenous tissue. 
ll 
zym. gran. zymogenous granules. 
Fic. 1. A small duct surrounded by zymogenous tissue from the middle 
region of the pancreas of Scyllium canicula. The ductule is seen 
to consist of two layers of cells, as described in the text. The 
material was fixed in a saturated solution of corrosive sublimate 
and stained with hematoxylin and eosin. As seen under Leitz, 
Oc. 4. Obj. 7. Cam. luc. Reduced to % of the original size. 
Fic. 2. The section shows three small ducts, a quantity of adenoid tissue, 
and “clear areas” (Islets of Langerhans). Taken from the pos- 
terior region of the pancreas of Mustelus laevis. The two layers 
of cells in the ducts are very clearly shown, and the outer row 
can be seen to be directly continuous with the islet tissue. Some 
of the cells of the outer row are stained more deeply than others. 
The material was fixed in corrosive sublimate and stained with 
hematoxylin and eosin. As seen under Leitz, Oc. 4. Obj. 4. 
Cam. luc. Reduced to % of the original size. 
Fic 3. An islet from the middle region of the pancreas of #&hina squatina. 
The large, irregular cells of the islet are seen surrounded by 
zymogenous tissue whose granules are beautifully stained. The 
material was fixed in Flemming’s fluid and stained with safranin. 
As seen under Leitz. Oc. 4. Obj. 7. Cam. luc. Reduced to % of 
the original size. 
Fic. 4. Shows several small ducts and islets surrounded by zymogenous 
tissue, from the posterior region of the pancreas of Rhina squatina. 
Here and there the islet cells are seen encroaching upon and 
replacing the zymogenous elements of the tubules. The material 
was fixed in Flemming’s fluid and stained by Heidenhain’s iron- 
hematoxylin method. As seen under Leitz. Oc. 4. Obj. 7. Cam. 
luc. Reduced to % of the original size. 
