Abstract
To obviate the complication of nutritional disturbances produced by hypophysectomy, the left nipple of several monkeys was painted daily with a soln. of 0.05 mg. per cc. of estrone in 95% alc. To the right nipple alcohol alone was similarly applied. Finally, the breasts were removed and the mammary glands were fixed, dissected, strained and cleared, and studied as whole mounts. In all cases the left mammary gland was distinctly larger than the right one.