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Hormones are these internal secretions that come out of a gland, and they go through the blood, but they go to a specific target.

In many cases the internal secretion is no mere accumulation, e.g. the internal skeleton of the Radiolaria, and the nematocysts of the Coelentera.

It is generally believed that the internal secretion of the thyroid and the adrenal are antagonistic.

Such an internal secretion would not be surprising in the light of all that we have learned of the physiological nexus of organs in recent years.

This was the first time in physiology that the idea of an internal secretion was advanced.