Lydia M. Dewitt 211
either direction, so that we find much the same appearance in whatever direc-
tion the sections are cut. These large sinusoids are connected at intervals by
smaller vessels and, as the greater part of the island is composed of superposed
layers of similar arrangement, it may easily be seen why so large a number of
sections through the larger portion of the area show a very similar arrangement
of cords of cells and blood-vessels. The rich branching of the larger vessels
and the connections of the smaller ones may also be seen in the figure.
Since the arrangement of the blood-vessels regulates the arrangement of the
bands and groups of cells, a description of the one figure necessarily involves
a description of the other. The resemblance of the cords of cells to tubules
and acini appears more marked in the interior of the model than in the exterior
view. It may be repeated, however, that not only is no lumen found, but
there is not even any arrangement of cells which would suggest a lumen. The
cells are most irregularly grouped, and the only suggestion of regularity of
arrangement seems to be due to their following the arrangement of the blood-
vessels. The cells of the human areas vary in size and structure and may be
divided into about the same classes as were described for the guinea-pig. The
amount and arrangement of the insular connective tissue vary more than any
other portion of the structure. In the child's pancreas, there is very little
or no connective tissue within the island, the sinusoids resting directly upon the
epithelial cells. A space may often be seen between the capillary wall and the
* , . ..
A
Fig. 8, A and B.-Sections of areas of Langerhans from pancreas of four-
year-old child. X 200.
epithelial cells, indicating that the cells have shrunken somewhat either in the
fixation or as a result of post-mortem change. No such spaces were observed