Lydia M1. Dewitt 199
6. o0I3 x o.I8 x o.I mm . ................ o.oo26 c. mnm.
7. o.Io x o.I3 x O.I25 mm . ............. o.ooi6 C. mm.
8. O.I2 X O.I7 X O.I8 mm .. .. ... 0.0037 C. mnm.
9. o.I5 x . X 0.2 x o.25 mm . ................ 0.0065 c. mm.
Io. o.i2 x o.27 x o.28 mm . ...........0.... o.oo98 c. mm.
They are usually oval or elongated in shape wvith quite regular contour, rarely
lobulated or even with marked projections. Near the periphery of the pan-
creas, the areas are relatively small and spherical or oval, while near the central
portion of the gland in the neighborhood of the larger ducts, especially at about
the junction of the splenic and middle thirds, thc areas are large and prominent.
In this region, especially large islands are occasionally found, analogous to
the giant areas described by Laguesse in the human pancreas. These often
seem to have no connection with the pancreatic acini, being surrounded by the
fibrous connective tissue and adipose tissue around the duct. While they
vary in shape, many of themn are much enlongated, being several times as long as
they are wide, some having been found measuring o.g to I.o millimeter in actual
length and I I 5 to I 20/, in width. In this region also masses of lymphoid tissue
are occasionally seen, easily differentiated from the islands by the different
character of the cells and by the arrangement of the cells and blood-vessels.
The number, position, and relations of these central areas are represented in
Fig. I, a low power drawing of one of the main ducts of the pancreas of a guinea-
pig, with the surrounding connective tissue and blood-vessels. In this small
mass of tissue, measuring 3.2 mm. inlength, five relatively large areas arc seen,
and three others were just beyond the field of vision. A small amount of pan-
creatic tissue is seen in the section, but it has no close relation to the areas of
Langerhans, which are distinctly encapsulated. Occasionally at the periphery
of the pancreas in the adipose tissue of the surrounding mesentery, I have seen
areas which appeared to be free. Usually by tracing such areas through the
series of sections in which they occur, some few pancreatic tubules are seen in
loose or close relation with then.
Fig. i.-Large duct from pancrcas of guinea-pig, showing surrounding con-
nective tissue and blood-vessels with a small amount of glandular tissue and
five relatively large areas of Langerhans. I, areas of Langerhans; p, pancreatic
acini; v, blood-vessels; d, duct. X 25.
The discovery of such relatively isolated islands suggested to
me the possibility that isolated areas might be found in the