216 GEORGE W. CORNER 



balls. The capillaries are so numerous that every acinus is en- 

 circled by a mesh of the net at intervals of 15 or 20 micra. There 

 is no regular relation, within the unit, between the duct and the 

 blood-vessels. As mentioned before, according to the position of 

 the unit with respect to the nearest duct and artery, its ductlet 

 and arteriole may enter it at adjacent, or at opposite points 

 (fig. 17, A). The duct to a single unit has a diameter of about 

 0.015 to 0.020 mm.; and the artery measures about 0.0125 mm. 

 in diameter. 



THE ADULT PANCREAS 



The fresh pancreas of the pig presents an irregular surface 

 which gives at first the impression of being divided into lobes. 

 However, if one take a blunt probe and separate the areolar tis- 

 sue between these lobes, all semblance of regularity in them is 

 lost, as the dissection divides the organ into an increasing number 

 of parts. But when the dissection has proceeded so far that the 

 probe can go no farther without tearing glandular tissue, it is 

 found the organ has been divided into a large number of small 

 masses of surprisingly regular size. These masses, which as 

 found in the pig's pancreas agree with the secondaiy lobules or 

 lobule-groups described by Opie (and themselves called lobules by 

 Laguesse), are of somewhat varying shape, generally rounded, 

 wedge-shaped, or roughly pyramidal. They average about 0.025 

 grams in weight (formalin specimen washed in tap-water and 

 dried on filter-paper); and as the average weight of five entire 

 adult pancreases dissected cleanly and weighed under similar 

 conditions was 41 grams, an adult pancreas of normal size is 

 composed of about 1000 lobule-groups. In injected specimens 

 one artery is found by dissection to enter each of these lobule- 

 groups, which in turn is drained by one duct. The average 

 diameter of th-e artery is 0.136 mm., the duct 0.093 nma. The 

 ducts from lobule-groups unite in tree-like form, becoming at 

 last lateral branches of the main-duct, entering it at right-angles 

 all along its course. The grosser pancreatic ducts in the pig 

 sufficiently resemble those of the dog, illustrated by Revell with 

 beautiful corrosions ('02) to render further description unneces- 

 sary here. 



I 



