It seems almost absurd that a physician should tell patients that it will do them good to practice smiling, to take every possible opportunity to laugh, and even to take frequent glances into a looking glass, to see that they are not pulling long faces. The difference between a feeling of melancholy and one of gladness consists mainly in the position of the outer angles of the mouth. The putting into practice of the maxim, not to let the sad lines dominate the countenance, but to insist on keeping the others there as far as possible, means much for the correction of internal feelings of depression and discouragement that may be badly interfering with the flow of nerve impulses from the brain to the body. Mouth Breathing.--Since Meyer's discovery of the overgrowth of the {106} lymphoid tissue in the pharynx, we have learned to appreciate how important is mouth breathing, even for the intellectual life. We all knew before, and indeed from time immemorial it was well understood, that, as a rule, people who went around with their mouths open were of low grade intelligence. All sorts of methods were used to teach these young people to keep their mouths shut. They were reminded of it at home, they were told about it at school, and, if they married, their wives tried to keep them from this apparent manifestation of lack of intelligence. Of course, they were not, as a rule, able to carry out the well-meant intentions of their friends and advisors. The mouths were kept open because they could not breathe normally through their noses, and so respiration had to be accomplished by the only other available avenue. As a consequence of the open mouth, the lips were inclined to roll out somewhat, and certain indications of the human physiognomy were supposed to be associated with these thick lips.