1. Quantitative estimations directly associate the phosphate phosphorus precipitated by iodine solution from active extracts of the anterior lobe pituitary in dilute acetic acid with the metamorphic activity of the lobe.
2. Substitution of the phosphate content of the iodine precipitate by other radicles (sulphate, acetate, picrate, etc.) results in the loss of activity.
3. The active factor is insoluble in alcohol, chloroform and ether, which distinguishes it from Robertson's growth-promoting tethelin.
4. The melanophore stimulant is independent of the phosphate content.
5. There is a small quantity of phosphate precipitated by iodine solution from posterior lobe extracts which indicates, apart from post-mortem diffusion, either the presence normally of the active factor in this lobe (Cone of Wulzen) or the existence of some other phosphate combination precipitated by iodine, but in effective in metamorphosis.