even the far more grave operations which are now done, the general mortality will scarcely exceed five per cent., and many surgeons are able, in a series of several hundred operations, to save ninety-seven out of every hundred patients! SERUM TREATMENT Another remarkable recent discovery, the result of numerous and careful investigations in the laboratory, is a wholly new means of treatment, viz., that method which is known as orrhotherapy, or serumtherapy, or the treatment by injecting certain antitoxins under the skin by a hypodermatic syringe. It would lead me too far to enter into the theory upon which these were first used. Suffice it to say that in the blood of an animal that has passed through a certain disorder the liquid part of the blood contains an antidote or antitoxin. If a certain amount of this is injected under the skin of an animal or man suffering from the same disorder in its incipient stages, the antitoxin prevents the development of the disease. The use of this method has thus far been much more medical than surgical, and its results in diphtheria and other medical disorders have been perfectly marvellous. In surgery, however, less favorable results have been obtained, but in all probability in the future we shall be able to do for some of our surgical disorders what the physician can do to-day for diphtheria. [For the results in diphtheria, see Professor Osler’s paper.] There has also been discovered another means which in surgery has rendered some valuable service. From certain organs, as, for instance, the thyroid gland (the gland whose enlargement produces goitre), we can obtain a very potent extract of great value. In cases of goitre very noteworthy results have already been obtained by the administration of the thyroid extract. A number of other organs in the body of animals have been used to combat certain disorders in the human body with advantage. The chief development of both of these new forms of medication, however, will take place in the twentieth century. INSTRUMENTS OF PRECISION