Interest in sour milk drinks has become quite general in recent years through the work and teaching of Metchnikoff, who believes that their use will aid materially in prolonging life and delaying the changes incident to old age. However, most people dislike sour milk and will not use it, so several years ago the writer undertook to prepare sour milk drinks so flavored with fruit juices as to make them more palatable. The dairy section of the Iowa Agricultural Experiment station took up these experiments and produced a frozen sour milk product of the consistency of ice cream and possessing a delicate and agreeable flavor. This frozen product was called “lacto” and as such became widely known, not merely in this country but in other countries as well.