Abstract
When the epithelial hypophysis is ablated in early embryonic stages in the frog, the resulting larvæ suffer in a characterisic way from defects in their pigment system. An equally definite set of alterations is produced in the other glands of internal secretion. Both Allen and the writer have reported the underdevelopment of the thyroid gland to which may in turn be attributed the failure of metamorphosis in these larvæ. The posterior lobe of the hypophysis in these larvæ is always present, though greatly underdeveloped—ample proof apparently of the need of coassociation with the epithelial portion of the gland. Most emphatic is the effect produced on the adrenal, whose cortical or interrenal substance is greatly decreased. This discovery was greatly facilitated by the employment of those methods which fix and stain the lipoids of the cortical tissue. These changes in the adrenal tissue do not occur in thyroidectomized larvæ and are consequently not to be referred to the thyroid reduction which is coincident with them.
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