THE INTER-BELATION OF THE THYREOID AND HYPOPHYSIS IN THE GROWTH AND DEVELOPMENT OF FROG LARVAE

Abstract

In attempts at establishing the function of the ductless glands, investigators are limited to relatively a few kinds of experiments. One can administer a particular gland to an animal or transplant the gland into the animal in the hope of bringing about a condition wherein the subject receives more than the normal amount of the hormone being studied. One can extirpate a gland from an animal and then administer to it preparations of the type of gland removed, and one can remove a gland of one type and administer prepared glands of another type. Still further, various combinations and modifications of the above kinds of experiments can be attempted. The unsatisfactory elements in ductless gland investigations are difficulties of controlling the experiments and the greater difficulties of interpretation of the results. In administering ductless glands one must admit that the preparations are abnormal to begin with. The glands used are dead and only hormones that are relatively stable can be preserved.