THE PHYSIOLOGIC FUNCTIONS OF INSULIN
J. J. R. MACLEOD
Toronto, Canada
February 9, 1923
I wish to say that I consider it a great honor to be asked to address
a society such as this, that stands for the best ini medical science.
In introducing the subject which I have been asked.to talk to you
about tonight, I would like to remind you that the earliest investiga-
tions showing that there is a relationship between the pancreas and
diabetes extend as far back as the seventeenth century, when Conrad
Brunner showed that the pancreas could be excised in dogs without
any definitely unfavorable symptoms supervening. The experiments
were made with the object of showing that this gland is not essential
for digestion, but incidentally it was noted that the animals behaved
in a most peculiar manner. They exhibited definite symptoms of hun-
ger and of diuresis. It is also interesting to note that an even earlier
investigator, Malpighi, as a result of what he described as excision of
the spleen, noted also in dogs that the animals exhibited symptoms
which seem to have been those of diabetes. The chief outcome of
Brunner's investigations was to divert men's minds from the pancreas,
for it seemed from his results and those of his contemporary, Peyer,
to be definitely established that this gland could have no essential
function in the well-being of the animal. Even in the textbook of
Johannes Miller, published during the first quarter of the nineteenth
century, only a few paragraphs are devoted to the function of the pan-
creas; many pages, however, being devoted to the function of the stom-
ach, for by that time the work of William Beaumont, done in this coun-
try, had become known in Europe. It was from clinical sources that
the incentive to further investigation of the pancreatic function came.
Cowley and Bright, and later the French physician Bouchardat, showed
that there is a definite relationship between disease of this gland and
diabetes in man. The belief in this association gradually grew; grew
in that peculiar way in which impressions grow in every science, but
particularly in medical science, and men's minds became more and
more directed to the possible relationship between the pancraetic func-
tion and diabetes. Claude Bernard, among others, was attract¢d by
this possibility, and although most of this master's work on the Ipn-
creas pertained to its digestive function, he also endeavored to seek for