carried on a series of logical
syllogisms, built upon unreal pictures of a straight path to the East,
Claude Bernard opened up the continent of the internal secretions to
the experimental enthusiasts of his time by a discovery which today
is not grouped among the phenomena of internal secretion at all. In
attempting to throw light upon the disease diabetes, in which there
is a loss of the normal ability of the cells to burn up sugar, he
examined the sugar content of the blood in different regions of the
body. He found that the blood of the veins, in general, contained less
sugar than the blood of the arteries, which meant that sugar was taken
from the blood in passing through the tissues. But the venous blood of
the right side of the heart contained as much sugar as the arterial
blood. Evidently, somewhere, sugar was added to the blood in the veins
before it got to the heart. The blood of the vein which goes from
the liver to the right side of the heart was then found to contain a
higher percentage of sugar than is present in the arteries. The vein
which transmits the blood from the intestines to the liver had
the usual lower percentage of sugar corresponding to the analysis
established for the other veins. The liver, therefore, must add sugar
to the blood on its way to the heart. Extraction of the liver then
revealed the presence in it of a form of starch, an animal starch,
which Bernard called glycogen, the sugar-maker. The origin of the
sugar added to the blood on its way from the liver to the heart was
thus settled. Bernard went on to hail glycogen and the sugar derivable
as the internal secretions of the liver, and to erect, and then drive
home, a theory of internal secretions and their importance in the body
economy.

The case he had hit upon was exquisitely fortunate, as the liver had
hitherto been regarded purely a gland of external secretion, the bile.
Nowadays, glycogen and the blood sugar are not considered internal
secretions, because they are classified as elementary reserve food,
while the concept of the internal secretions has become narrowed down
to substances acting as starters or inhibitors of different processes.
Moreover, the process of liberation of sugar from glycogen itself in
the liver, upon demand, is today set down to the action of an internal
secretion, adrenalin. Claude Bernard's conception, like a novelist's
characters, has turned upon its creator, taken on a life of its own,
and evolved in