Till. Explanation of the Plates. 



Lettering common to all the figures. 



ad. = adenoid tissue. end. = endothelium of blood 



bath. c. = bathyclirome cells. vessels. 



bath. gran. ^^ bathyclirome granules. i. = islet of Langerhans. 



bath. syn. = bathychrome syncytium. • /. = lumen. 



bath. t. := bathychrome tissue. lept. c. = leptochrome cells. 



bid. c.^^ red blood corpuscles. lept. t. = leptochrome tissue. 



c. a. c. — centroacinar cells. trans, c. = transitional cells. 



cap. ^= blood-capillaries. zym. = zymogenous tissue. 



,comi-tiss. = connective-tissue. zy7n. gran. = zymogenous granules 

 d. = duct. 



Fig. 1. Islet of Langerhans from the splenic end of the pancreas of a normal 

 dog, showing the „alveolar" form of the islet tissue. The leptochrome 

 tissue of the islet is seen to consist of solid branching columns of cells 

 for the most part, two deep , separated by wide capillary blood vessels. 

 In some places the zymogenous tissue immediately surrounding the islet 

 contains some bathychrome cells. The material was fixed in Flemming's 

 fluid (strong) and stained by Heidenhain's iron-haematoxylin method. 

 As seen under a magnification of 500 diameters. Cam. lue. Reduced to 

 ^/a of the original size. 



Fig. 2. Islet from the free end of the pancreas of a normal dog, showing the 

 more solid form of the islet tissue. The leptochrome .tissue of the islet 

 is not distinctly arranged in branching columns, but in masses of irregular 

 shape separated by capillaries, which are not so wide as those depicted 

 in the preceding figure. Fixed in corrosive sublimate and stained with 

 haematoxylin and eosin. Same magnification as preceding figure. Cam. 

 lue. Reduced to '•'/3 of the original size. 



Fig. 3. A section from a portion of the splenic end of the pancreas of a normal 

 dog, drawn with the camera lucida under a low power of the microscope. 

 The islets are few and small. Fixed in corrosive sublimate and stained 

 with haematoxylin and eosin. Reduced to ^/;, of the original size. 



Fig. 4. Section from a portion of the splenic end of a dogs pancreas which had 

 bc(!n exhausted by the injection over a period of several hours of secretin 

 into tlic, s;i|ihen<)iis vein. The islets are distinctly larger and more luimerous 

 tli.iii ill tlic resting state. Corrosive sublimate, haematoxylin and eosin. 

 <';iiii. Inc. Saints niagniticalion as tig. 'I. Reduced to -/.j of tiie oi-jginal size. 



