Lydia M. Dewitt 215
number is smaller and the size greater than is apparent in any one section.
The lighter areas represent the islands of Langerhans, and the darker portion
the glandular t ssue wrhich I may say in passing seems to me to form definite
tubules and acini, as in the pancreas of other
vertebrates and not, as stated by Pugnat, a
recticular stucture like the liver, although
under lowv power it does prcsent a reticular
appearance
The cells of the bird's islands are smaller
itiS~ ~ and more uniform in size and structure than
those found in the islands of any other verte-
brate examined, scarcely any variation in size
jL~; l;,' ~ or stain of nuclei being noted. The cell out-
lines can scarcely be made out. The nuclei
are small, round, or more often oval, with a
very distinct nucleolus. Both nucleus and
protoplasm stain faintly. The cells are ar-
ranged in definite cords between the sinusoids,
wvhich here are wide and prominent because
of the congestion. Fig. I2 reproduces a cen-
tral section of an area of Langerhans from t he
Fig. I2.-Section through cen- pancreas of the dove, the blood cells in the
tral portion of dorsal pancreas of sinusoids being omitted. Fig. 13 repro-
duces three areas of Langerhans from the
pancreas of the dove,
in whi.h the blood-filled
sinusoids are especially
emphasized, the cells ap-
pearing lighter in the fig-
ure. They show three
types of arrangement: A C ~ ~g
shows the origin from a
larger vein of the main
afferent vessel, which Le
enters the island, pass-
ing along one side and
dividing into two main = l
branches near the end. c
Most of the other bran- , s,
ches are given off from
one side of the main
sinusoid, these again di-
viding and passing in
different directions. A A
large branch is given Fig. I3, A, B1, C.-Three sections of physiologically
off from the main injected areas of Langerhalls of dove, the injectel
sinusoid, which passes sinusoids being especially emphasized in the figure.
back, winding partly X 2.
under the latter, and supplies the proximal portion of the area This is