In the records of the mothers on modified oat diets, the young in certain cases continued to grow after the 25th day, at which age they may be safely weaned if supplied with a good food mixture, and if their growth was optimal during the nursing period. This fact is evidence that even after the young are able to eat of the deficient diet from which the mother has produced milk suitable only for subnormal growth, and on which they would be unable to grow at all, they are capable of developing in a fairly satisfactory manner for a time if they are supplied with a small contribution of their mother's milk to supplement the deficient cereal diet. There can be no doubt that they were still receiving a supplementary milk supply from the mother and that this served to enhance the incompletely supplemented oat diets available. Under adverse circumstances, therefore, a young animal restricted to an inadequate diet can be safely tided over a considerable interval, during which it would succumb were it not for the peculiar relation between the mammary gland and the blood, through which it secretes into the milk certain nutrient principles in amounts larger than those present in the food of the lactating female.

The inorganic content of all the plant seeds is the limiting factor in preventing growth in young animals restricted to such a diet, and in determining the quality of the milk secreted by a female taking a seed diet. Although the young, after reaching a state of independence of the mother, cannot grow at all on a seed diet unless it is enhanced with respect to certain mineral elements, the mother is able to take such a diet without salt additions and to produce milk therefrom which is capable of inducing at a slow rate growth in the young. It is apparent that one of her most important relations to her dependent offspring lies in her capacity to provide for them more adequate nutrition than she herself may be able to secure. This applies with special force to the inorganic moiety of the milk she produces for them.