Pawlow turned this discovery of his to a very practical use. He has a dozen or more healthy dogs which he calls his Dog Dairy. From these dogs he collects daily a quart or more of gastric juice, or appetite juice; and the dogs produce this large quantity without taking a particle of food into their stomachs. The juice is carefully filtered, and bottled and shipped all over the world to those physicians who are in touch with Pawlow and his work, and by them are administered to human patients. It is given to those patients who are deficient in gastric juice, and is used in very obstinate cases of indigestion. Pawlow collects his juice by having openings made in the throat and in the stomachs of the dogs. When the dogs are hungry they are given food of kinds which they particularly like, and they are allowed to smell the odor and to become excited over the prospect of eating it before they are actually allowed to have it. With the first sight and odor of this food, the dogs begin to secrete the appetite juice, which flows from the opening made in their stomachs through tubes into receptacles. Then when they begin to eat their food, the food does not reach the stomach at all, but simply passes through the openings in the throat into a receptacle before the dog, and the dog can go on eating the same meal over and over again. They thus enjoy themselves thoroughly for a long time. When the appetite juice ceases to flow, the process of feeding them in this manner stops, and they are given a real meal. VIII HEALTH AND THE MIND This account of Professor Pawlow’s experiment leads directly to the all important subject of the influence of mental states upon digestion and assimilation. Dr. Saleeby has published a book called “Worry, the Disease of the Age”—the very title of which shows the attitude of physicians upon this question; and the bad opinion which mankind has always entertained of such states of mind as “the blues” has now been scientifically justified. The effects of pain and pleasure upon digestion have been demonstrated by actual experiments in the laboratory of the St. Petersburg professor. A vivid account of these experiments has been given to the writers by Dr. J. H. Kellogg, who witnessed them about a year ago. Dr. Kellogg writes: “Professor Pawlow took Professor Benedict and myself into a quiet corner of his laboratory, and there we found a dog that had his salivary glands or ducts arranged so that by means of little tubes passing through the skin all the saliva, instead of passing down his throat, passed out through the tubes and could be collected in small glass bottles suspended beside his neck.