The growth curves of the famous Hopkins' rats are familiar to anyone who has ever opened a textbook of physiology. One recalls the proud ascendant curve of the milk-fed group which suddenly turns downwards as the milk supplement is removed, and the waning curve of the other group taking its sudden milk-assisted upward spring, until it passes its fellow now abruptly on the decline. 'Feeding experiments illustrating the importance of accessory factors in normal dietaries', Jour. Physiol., 1912, xliv, 425, ranks aesthetically beside the best stories of H. G. Wells.

There is no substitute for mother's milk.