Due to the impossibility of preparing the alkali salts of the barium and iron acids so as to be positive that the resulting preparations completely represented the barium and iron acids, and due to the insolubility of the acids and the total resins in solvents from which they would not again be precipitated when introduced into the circulation, it was found necessary to make an emulsion. The emulsifying agent used was acacia (gum arabic). It was possible by careful preparation to make a permanent emulsion that was miscible with water in all proportions to form a homogeneous mixture. The animals used were rabbits of about six pounds weight. The injections were made by Dr. Geo. McCoy, director of the Leprosy Investigation Station at Kalihi. All the physiological experiments were made at the bacteriological laboratory at the Leprosy Investigation Station. One cubic centimeter of the emulsion of the total resinous extract (strength 1 in 5) was injected into the ear of a rabbit; the animal died immediately. Another rabbit was injected in the same manner with one half cubic centimeter of the same preparation. The animal immediately stretched out and became rigid, or appeared to be paralyzed, but after several minutes these symptoms lessened and after about five minutes the rabbit appeared normal as far as activity was concerned. As soon as the rabbit had recovered a second injection of one quarter of a cubic centimeter of the same preparation was injected in the same manner into the same animal. The same symptoms were produced and with equal intensity, but ten minutes passed before the animal again became conscious. For several minutes after recovery the animal appeared somewhat drowsy and stupid but it soon regained its former activity. One half cubic centimeter of the iron acid emulsion (strength 1 in 7) was injected into the ear of a rabbit. Immediate paralysis and apparent anaesthesia set in lasting very pronouncedly for eight minutes. The rabbit’s head was drawn backwards and its legs stiffened giving symptoms similar to strychnine poisoning but they did not persist. When a second injection of one quarter cubic centimeter was given to the same animal, the same symptoms were produced, the animal remaining under the influence of the injection for about fifteen minutes. The iron acid injection was repeated on another rabbit with the same pronounced symptoms of strychnine poisoning but the effect lasted only about ten minutes.