1. Metamorphosis can, as originally stated by Hogben, be induced in the neotenous axolotl larva of the Mexican salamander by regular injection of fresh extracts of the anterior lobe of bovine pituitary; the failure of Smith to obtain this result in experiments upon the Colorado axolotl appears to be due to the necessity of performing the extraction in acid medium.
2. Such traces of melanophore stimulant as are found in the anterior lobe of the mammalian pituitary result from post-mortem diffusion.
3. The substances responsible for production of metamorphic changes and pigmentary response are not identical.