216 Jforlpolo(]y aad Phlysiology of Areas of Langerlba,s
a relatively thin section, so that marry of the tortuous capillaries are discon-
tinuous, but it indicates very well the connections and arrangement of the
insular vessels. B shows the main sinusoid passing through the center of the
area and sending branches to either side, while C represents a radial branching
from a central large sinusoid. C might, as will be readily seen, represent a
transversc section of B.
In the frog, the islands stain more deeply and are so diffusely
and irregularly scattered among the pancreatic tubules that count-
ing and measuring are very difficult. It is almost impossible to
determine how many of the small island masses seen among the
acini belong to a single area or to be certain as to the limits of
the areas. The most of the area sections seen by me were relatively
small, averaging .002 c. mm. in size, the dimensions averaging
about 90 p x I20 p X 2I0 p. The cells differ somewhat in char-
acter from those in the other areas studied, since very tall col-
umnar cells with elongated, deeply stained nuclei predominate.
These are crowded together, usually in a single row, especially
in the central portion to form the very distinct cell bands so
characteristic for amphibia; they resemble those described and
figured by Diamare for the triton. He states that "the small
epithelial cords are rather delicate, formed of rather slender cells,
closely approximated and are separated by large capillaries.
These last evildently correspond to the 'large venous sinuses' of
v. Ebner. No capsule separates the areas from the zymo-
genic tissue." Pensa also in speaking of the cylindric
cells c)f the islands of amphibia, says: "These cells are not ag-
gregated into cords but are arranged in linear series, one after
the other in single file." In addition to these narrow crowded
cells which make up the central cords, masses of polygonal cells
with spherical nuclei are usually found, especially at the periph-
ery of the islands. V. Ebner described these islands in the frog
as early as 1 872, stating only that they showed no lumen penetra-
ble by a mass injected into the duct and that rather large veins
are found near the islands. In his later communication in I899
he states that he regards the vessels of the areas of Langerhans
in the frog as venous.
Fig. 4 represents a very typical area from the pancreas of the frog, with its
tall, narrow columnar cells with oblong, deeply stained nuclei arranged in