It is interesting to see how far we can account for the strange movements of laughter as part of the inherited automatic mechanism of man. Why do we laugh? What is the advantage to the individual or the species of "laughing"? Why do we "express" our pleasurable emotion and why in this way? It is said that the outcast diminutive race of Ceylon known as the Veddas never laugh, and it has even been seriously but erroneously stated that the muscles which move the face in laughter are wanting in them. A planter induced some of these people to camp in his "compound," or park, in order to learn something of their habits, language, and beliefs. One day he said to the chief man of the little tribe, "You Veddas never laugh. Why do you never laugh?" The little wild man replied, "It is true; we never laugh. What is there for us to laugh at?"--an answer almost terrible in its pathetic submission to a joyless life. For laughter is primarily, to all races and conditions of men, the accompaniment, the expression of the simple joy of life. It has acquired a variety of relations and significations in the course of the long development of conscious man--but primarily it is an expression of emotion, set going by the experience of the elementary joys of life--the light and heat of the sun, the approach of food, of love of triumph. Before we look further into the matter it is well to note some exceptional cases of the causation of laughter. The first of these is the excitation of laughter by a purely mechanical "stimulus" or action from the exterior, without any corresponding mental emotion of joy--namely by "tickling," that is to say, by light rubbing or touching of the skin under the arms or at the side of the neck, or on the soles of the feet. Yet a certain readiness to respond is necessary on the part of the person who is "tickled," for, although an unwilling subject may be thus made to laugh, yet there are conditions of mind and of body in which "tickling" produces no response. I do not propose to discuss why it is that "tickling," or gentle friction of the skin produces laughter. It is probably one of those cases in which a mechanism of the living body is set to work, as a machine may be, by directly causing the final movement (say the turning of a wheel), for the production of which a special train of apparatus, to be started by the letting loose of a spring or the turning of a steam-cock, is provided, and in ordinary circumstance is the regular mode in which the working of the mechanism is started. The apparatus of laughter is when due to "tickling" set at work by a short cut to the nerves and related muscles without recourse to the normal emotional steam-cock.