Experiments are described in which the thyroid or thymus gland of rabbits was removed prior to inoculation of the animals with Tr. pallidum. The effect of these procedures is described from the standpoint of the manifestations of the disease. After complete thyroidectomy, the disease was considerably more severe than in the controls and very markedly so in certain instances. Partial tyroidectomy, on the other hand, resulted in a milder disease than that of the controls. The effect of complete thymectomy was less pronounced than that of either complete or partial thyroidectomy, but, in general, the syphilis resembled that in partially thyroidectomized animals.
These effects are discussed in relation to the host's reaction and resistance to experimental syphilis and the conclusion was reached that the integrity and balance of the glands of internal secretion play an important rôle in the mechanism of defense against this infection.