1. There is a marked individual variation in the histological structure of the thyroid gland of rabbits examined at the same season under standard conditions. Although the microscopic appearance varies in different rabbits, the structure of the two lobes in the same animal does not differ. The variations are seen principally in the size and shape of the vesicles and in the quantity and character of the colloid.
2. With one lobe as a control no histological changes in the other lobe have been observed following section or stimulation of either the cervical sympathetic or the vagus and its branches.