T h e evaluation of the effects of drugs, which are applied in the sockets or in the mouth, on the healing of wounds after extraction of teeth is a difficult problem. The reaction of the patient to the operation and of the tissues to the trauma incident to the operation varies so greatly that any clinical study must necessarily be somewhat inaccurate. Other factors such as the age and condi tion of health of the patient, the condi tion of the tissue and bone surrounding the tooth, as well as the type of organism predominating in the mouth at the time of the extraction, undoubtedly play a part in the process of healing. Unfortu nately, accurate methods of measuring the effect on healing of each of these fac tors are not available. Claflin1 found in his work on the heal ing of extraction wounds in dogs that “ the formation of a blood clot was the beginning of tissue regeneration in un disturbed healing of extraction wounds in dogs.” Most of us feel that the proper healing o f a wound in the mouth begins with the preservation of a healthy blood clot. Whether or not final healing pro gresses at about the same rate regardless of the presence or absence of the blood clot, the fact remains that the patient is much more comfortable and the healing