Lydia M. Dewitt 197
Dogiel by the Golgi method, and Kûhne and Lea and also
v. Ebner by injecting the ducts, showed that the areas of Lan-
gerhans are not connected by permeable ducts to the excretory
ducts of the pancreas, although Lewaschew believed that some
of the injection mass penetrated within the island. His results
are believed to be due to an extravasation of the injection mass.
Laguesse divides the areas of Langerhans of man with
respect to their size into very small, less than Ioo00 . in
diameter; small, I00oo to I50o; medium, I50o to 20oo0u; large,
over 200o/ in diameter; and giant forms (very rare), over 4oo0
in diameter.
After examining ten human subjects, Opie determined that
there was in the head of the pancreas an average of 0.366 areas
to the square millimeter, 0.36 in the body, and 0.68 in the tail,
those in the tail being therefore four times as numerous in the
cubic millimeter as in other parts of the pancreas. Sauerbeck
in twelve human subjects finds an average of one per square
millimeter, while Laguesse in six subjects finds an average of a
little less than one per square millimeter and regards anything
less than 0.5 per square millimeter as a diminution. He states
that the one-hundredth part of the pancreas is area of Langerhans.
As to the distribution of these areas, Opie states that they are
four times as numerous in the tail as in any other part of the pan-
creas and are situated in the center of the lobule, at least in
the cat, in which he finds one area in each lobule in the splenic
portion of the gland. In man, he says the number is more variable.
My own investigations on the morphology and histology of
the areas of Langerhans have been made (I) by reconstruction
by the Born wax-plate method of areas of Langerhans from
man, cat, rabbit, and rat, and also of injected preparations from
cat; (2) by careful study of serial sections of injected and un-
injected preparations of pancreas of man, cat, rabbit, rat, guinea-
pig, frog, and bird. The tissues were fixed as soon as possible after
the death of the animal, in most cases in saturated aqueous
solution of bichloride of mercury, and imbedded in paraffin, and
serial sections averaging 5tl in thickness were cut. These were
stained in hæematoxylin and eosin, Mallory's connective tissue