Summary and ConclusionPreparations of the posterior lobe of the pituitary gland cause a marked increase in the weight of frogs which is found to he due to increased absorption of water. A comparison of the effects of pitocin, pituitrin, and of pitressin in producing an increased absorption of water indicates that pitocin is the most effective of the 3 in this regard. With the doses used, pitocin caused an average increase in weight of about 19%, whereas pitressin caused an increase of only 11%. The effects of pituitrin come practically midway between the other 2. About 5% of the excess water taken in through the skin may be held in the subcutaneous spaces along the sides, back, and legs. The rate of loss of water when frogs are renioved fron the water is definitely increased by injections of pitocin.