How thoroughly Dr. O'Dwyer realized all the difficulties attached to the practice of intubation may be gathered from some of his articles on details of the treatment of patients necessary in order to make intubation a success. One of the great difficulties in the matter was the liability, when a tube was in place, for food and drink to find their way, during the process of swallowing, into contact with sensitive tissues of the larynx. To overcome this difficulty, Dr. O'Dwyer made many modifications of the upper part of the tube. Accordingly he made many wax models of the larynx, and studied the function of the epiglottis and its method of covering the larynx in order to facilitate the complete protection of the laryngeal tissues during the process of swallowing. Finally, he succeeded in making a tube that enables most patients to learn how to swallow without much difficulty. In the mean time O'Dwyer was full of practical suggestions with regard to the management of these cases. His clinical experience showed him that it was better to teach the patients to swallow rapidly and then cough up any material that might find its way into the larynx rather than to take small sips with a spasm of coughing after each sip. He showed that, notwithstanding the apparently great danger {340} of portions of food being carried past the larynx into the trachea, and so to the lungs, there was not nearly so much risk in this matter as had been anticipated. The almost inevitable occurrence of pneumonia was supposed to be one of the serious objections to the use of the intubation methods. Careful pathological investigations, however, soon showed that pneumonia developed much less frequently than had been expected, and, as a rule, when it did develop, it was due to an extension of the diphtheritic processes from the throat rather than to any infection by material that, because of the presence of the tube, had been inadvertently allowed to find its way into the respiratory tract. However, O'Dwyer's work was not done without considerable opposition. Bouchut's original invention of tubes for the larynx had failed to attract attention because of its condemnation by the Academy of Medicine of Paris, under the influence of Trousseau. When O'Dwyer's tubes were first suggested, then, there were not lacking critics, who said at once that his method was not new, that it had been fairly tried already and found wanting, and that it was hopeless to expect that any intubation method would succeed, since the larynx would not tolerate such a foreign body. There are always those who are sure, on _a priori_ grounds, that a new invention cannot succeed because it infringes on certain well-known physical laws that make it impossible. Similarly there were a number of experienced clinicians who were sure that O'Dwyer's reported results could not be as represented.