A large amount of experimental work has been done during the past decade to impress on the public and profession the fact that raw milk is never a safe milk, and that in order to be fit for consumption all milk must be pasteurized. The effect has been that in many states legislation has been enacted governing and requiring the pasteurization of all milk with one exception, and this exception is certified milk. In view of the enthusiasm, entirely justified, of public health experts everywhere as to the value of pasteurization, suggestions have been rather numerous, particularly during the past two years, that even certified milk is not a safe raw product, and that it, too, should be heated. Without entering into the relative values of raw and heated milk in infant feeding, it is unquestionably permissible to say that with our present knowledge most pediatrists are still of the opinion that raw milk plays a very important and needed r\l =o^\l eduring the first two years of life, provided such a product can be obtained as is not a potential source of danger to the infants consuming it.It has always been the proud opinion of those medical men interested in the certified milk problem that in this product conditions as ideal as were possible had been met, and that for practical purposes certified milk was a safe raw milk. When the literature, however, began to offer suggestions here and there doubting its efficiency and safety, it became necessary for the problem to be attacked by those interested in it, in order that the foundation on which the movement had been built might be forever strengthened and its value be definitely proved, or, if it was not a dependable product, that this even more important fact should be elicited.