This is not to say that they were all of them “born tired.” Congenitally weak many of them may have been; but the more the investigators familiarised themselves with the asthenia of the lazy, the more they found reason for the belief that, as a rule, it was an acquired and functional rather than an inborn and organic weakness, although often initiated by local troubles organic in nature. Thus, studying laziness in children attending school, it was discovered that quite frequently their inertia is connected with the presence of adenoid, or abnormal tissue, growths, in the cavity back of the nose. These growths, by making it extremely hard for the child to breathe properly, deplete his vitality so that he remains undersized and is quickly fatigued by intellectual or muscular effort. The natural consequence is that he becomes more or less of an idler, bringing upon himself the reproaches and punishments of parents and teachers. What he actually needs is not scoldings or whippings but a slight surgical operation. Often a surprising development of both mental and physical power follows the removal of the adenoids. In one case, reported by Professor Swift, a girl of fourteen grew three inches taller within six months after an operation for adenoids, and at the same time showed an improvement in her school-work that contrasted strikingly with the apathy and dulness that had preceded it. Another, three years younger, grew six inches in about four months, and from being a sad idler was transformed into an unexpectedly attractive and bright pupil. A boy of twelve, backward both mentally and physically, likewise lost his dulness and laziness within an astonishingly short time after the impediment to his breathing had been removed. Dental defects also contribute materially to the development of laziness and mental retardation. This has been repeatedly demonstrated in individual cases, and at least one psychologist—Professor J. E. Wallace Wallin, of St. Louis—has demonstrated it in the case of a group of children. These children, twenty-seven in number, were pupils in a Cleveland public school; they were afflicted with tooth-decay to a varying extent, and they were mentally backward, being from one to four years retarded in their school-work. At Professor Wallin’s direction their teeth and gums were treated, they were taught to use a tooth-brush properly, and to chew their food thoroughly. Before the dental treatment began they were twice given five psychological tests, to ascertain their memory-power, attention-power, etc.; the same tests were twice given to them while the treatment was under way; and, six months after its termination, or just before the close of the school-year 1910-1911, the tests were again given twice.