Before presenting descriptions of new media for the determination of bacteria in milk, we wish to call attention to the fact that the media described give not only quantitative but, to a certain extent, qualitative results. If the new media achieved merely the same results as those now well known, we should not feel warranted in taking up the reader's time. It is believed that the time has passed when one can be satisfied with total counts only. Mere quantitative results in bacteriological milk analysis can not be interpreted satisfactorily unless something of the history of the milk is known. Often this "something" is missing; then one must interpret the count as due to this, that, or the other condition or a combination of them. This is not an attempt to discredit the total bacterial count, for it is very valuable as it stands, in milk-control work, but it is hoped that some of the media described in this paper will increase its value. The media extensively used in milk-control work have been (1) infusion agar, described in the standard methods of the American Public Health Association in 1910, and (2) extract agar, later adopted as a standard medium, its formula having been published by the association in 1916. Many who use the extract agar realize that it does not give the high counts which are obtained on the infusion agar, but use it because it is the standard medium for milk analysis. Even the members of the Committee on Standard Methods recognized the fact that extract agar is defective, as is shown by the state-565