Lydia M. Dewitt 287
qualitative and one quantitative, on a glucose solution with
an extract of these areas. The result would seem to show that
this extract does not alone have the power of inverting grape
sugar. He hints, however, that his experiments with this extract
on diabetic patients have been more favorable to the island the-
orv of diabetes. Diamare and Kuliabko, on the other hand, tested
in several cases the action of this island extract on starch solution
and on glucose solution. They were able to show, so far as
their few tests made can decide, that these islands have no power
whatever to digest starch. While the starch solution with the
pancreatic extract from the same fish gave with iodine no starch
reaction, and with Trommer's test gave marked sugar reaction,
that with the island extract gave only the starch reaction with
iodine. Their test for the glycolytic action is much less decisive,
since no change was noted until after forty-eight hours, so that the
inversion may have been due to bacterial action; further experi-
ments, therefore, are necessary. The outline which they give
of the work which they are now carrying on shows that they are
carefully investigating the chemical and physiological character-
istics of these isolated areas of Langerhans in the fish, and we
shall hope for much light on this question when their work shall
have been completed and their results published.
In conclusion it may be stated that there occur in the pan-
creas of all vertebrates homologous structures known as areas
of Langerhans.
These have the structure of vascular glands with a sinusoidal
circulation and are not changed during the secretory activity
of the pancreas. They also remain unaltered when the glan-
dular acini become atrophied as a result of ligation, section, or
obstruction of the duct.
They have a secretion which is probably poured into the blood-
vessels; this secretion has no digestive action on starch, fibrin,
or fat, but has a marked glycolytic function, especially when
added to muscle extract and is therefore analogous to the
"activator principle" described by Cohnheim.
In closing I am glad to acknowledge my indebtedness to