INTRODUCTION
The experiments described in this paper were undertaken after reading reports of the results of thymus extirpation by Klose and Vogt and by Matti, in the belief that it was possible to produce in animals, by means of removal of the thymus gland, a condition closely related to, if not actually identical with, the rickets of human beings. The experiments did not result, however, as we had been led to anticipate. In the course of them we had occasion to read the experimental literature on thymus extirpation and became impressed with the inferior quality of much of the work done and the conflicting character of the results obtained. The reviews of the experimental literature failed to convey a proper conception of the character of the investigations which served as a basis for the ideas and theories so freely expressed in regard to thymus function, and did not indicate the