Lydia M. Dewitt 207
that in the rabbit and other lower forms, as well as in some pathologic conditions
in the human infant, the connection with the tubules remains unbroken. As
seen in Fig. 5, the band-like arrangement of the cells is much less marked in the
rabbit than in other species, the bands usually consisting of so many and so
irregularly arranged cells that they may be spoken of rather as cell masses.
The character and arrangement of the blood-vessels and connective tissue
are very similar to that already described for the guinea-pig and rat. Fig. 6
represents a curious anomaly, two examples of which were found in the sections
of the rabbit's pancreas studied by me. These were not reconstructed. but were
carefully traced through the entire series
of sections in which the area appeared.
They .ere nearly spherical masses of per-
fectly normal island tissue, which hos-.
ever formed merely a shell, the interior
being filled with blood and having an
endothelial lining. The occurrence of this
blood vesicle or sinus, although only as an i s I
anomaly, may serve to lend some support
to the idea that the circulation here is
sinusoidal. Added interest is given to the
anomaly by the fact that Laguesse de-
scribes in sheep embryos forms in which thI
island cells form hollow balls, the interior
being filled with blood cells. A similar
appearance (blood vesicle) in the petro- '
myzon is mentioned by Pensa.
In the cor, the areas are as a rule much Fig. 6.-Section through center
smaller than in the other forms studied. of a vesicular area from pancreas
Twenty areas were measured, taken from of the rabbit, the interior of the area
different portions of the pancreas and being filled by a large blood sinus
from two different animals. The average surrounded by endothelial cells
size of all the areas was about o.oo27 which rest directly on a shell of nor-
mal island tissue. + 200.
c. mm. The average number per mm. was
I. 08, so that about T8f of the pancreas consisted of island tissue.
Cat I Cat II
i. .o8 x .io5 x .I8 mm..OOI5 c. mm. Iz2 x .I6 x .ii mm..oo002i c. mm
2. .I4 x .I9 x .I25 mm. .0033 c. mm. .iI X I7 X .I5 mm..ooa28 c. mm.
3. .I2 X .25 X .IO mm. .003 c. mm. .I9 x .32 x .T35 mm. .0082 c. mm
4. o8 X .I7 x .0o mm. .0oI2 C. mm. .07 X ,20 x .i3 mm. s.ooI8 c. mm.
5. .09 x .I8 x .I4 mm..0023 C. mm. .T2 x .9 x .20 mm..0046 c. mm.
6. .2i x .I3 X .23 mm..ooI9 c. mm. .23 X .25 X .I25 mm..o004I c. mm.
7. .o8 x .I4 x .I4 mm. .ooI6c. mm. .1i x .20 X .35mm..003 c. mm.
8. .îi x .I8 x r. mm. .02 c. mm. .I X .7 x.2 mm. .ooC9 . mm.
9. .I4 x .I6 x .20 mm. .0045 c. mm. .20 x .22 X.225 mm..0024 c. mm.
Io. .Io x .I4 x .I5 mm. .oo2ic.I mC. mm. I2 x .I7 X .I2 mm..so28 c. mim.
Avarage size .0024 C. mm. Average size .0034 c. mm.
It will be seen that the average size in the second series is greater