From time imemmorial milk has been regarded as the food best adapted to the complete nourishing of mammalia. It is the sole diet of all mammals during the earlier part of their postnatal development and is recognized as an excellent staple in the diet of the adult human, especially in the case of invalids. On the farm it is used extensively in the feeding of young animals, and in the case of the hog it is fed in large quantities to more mature individuals.

Within the last decade many investigations have been made concerning the nutritive value of milk and other food-stuffs and thruout these investigations milk has measured up to all expected standards. The object of this paper is to show that in spite of the high nutritive value of milk there are limitations to its use-limitations which are inherent, not in the milk itself, but in the class of animals to which it is fed.