196 Jiorphology and Physiology of Areas of Langerihaos
passing off from it to either side dividing each half into compart-
ments of fairly uniform size. Laguesse, on the other hand,
states that there is no connective tissue, but a thin, homogeneous
layer, which may be thickened in places ("pseudo capsule"),
and that a thin, amorphous sheath accompanies the principal
vessel and may spread out over the capillaries. V. Ebner says
that as a rule there is no connective tissue or membrana propria
between the island cells and the capillaries.
As to the blood supply of the islands, while all agree that
they are richly vascularized, there is some disagreement regard-
ing the character of the vessels. V. Ebner regarded them as
venous and was supported by Diamare. Kûhne and Lea state
that the vessels arise partly from capillaries and partly from
arterioles. Hansemann finds only capillary connections, and Opie
states that "the glomerularnet work is in very free communication
with the smallest arteries and that apparently the blood supply
is richer than that of other parts of the lobule." Laguesse states
that generally a principal vessel enters the island (rarely an
arteriole, generally a large branch continuous with an arteriole).
In a very recent article, which is profusely illustrated, Pensa
has reported the results of vascular injections of the areas of
Langerhans in a large number of species of vertebrates. He finds
the areas richly vascularized, mostly by a capillary network which
is a continuation of the intertubular capillary plexus of the pan-
creas. In some animals, as birds, guinea-pigs, arnd dogs, the
larger areas may show, in addition to the capillary vessel,
a small afferent artery, breaking up into a capillary plexus within
the island, the blood being then collected into a single efferent
vein. He does not state, however, how he distinguishes the
arteries from the veins, and while he states that the connection
is usually purely capillary, his Fig. 2 Plate IV, seems to indicate
that the connection with larger vessels is very common.
By the Golgi method, Pensa was able also to demonstrate a
very rich network of nerve fibers in the areas, the nerves passing
along the blood-vessels and also between the cells, and being
distinctly different both in number and arrangement from the
nerves of the acini.