Childhood, says A. W. Jones,1 is the period of life in which the greatest susceptibility to tuberculosis infection exists, and adult tuberculosis is generally an after-result of childhood infection. The true field of prevention in antituberculosis work, then, is obvious. Jones restates the opinion that the tuberculous infection of the individual does not occur by direct entrance into the blood through the air cells of the lungs, but always through the glandular system, either in the respiratory or alimentary tracts, and that in the vast majority of cases it occurs in infancy. If the infection occurs before the second year the patient promptly dies; if after the age of 2 the disease is more likely to become latent, and from this age up to puberty this tendency to latency increases with each year of age. What is called early tuberculosis in adults is generally the second stage or the beginning of the third, and at best it can be spoken of only as the early stage of pulmonary tuberculosis. Jones says that it should be the business of preventive medicine to forestall this stage. Logically, the upbuilding of the individual at the time of the true incipiency of the disease will give to Nature the greatest amount of assistance at the most applicable moment in the life of the disease. And as childhood is also the constructive period of the individual, the time when the tendency to normal cell-growth is at its highest, we may naturally expect the greatest returns for efforts expended, and the greatest percentage of absolute recoveries possible. Jones designates the public school as the “unworked field of preventive medicine” wherein most effective work in this line can be done. While this cannot be said to be a wholly “unworked” field—witness the active movement for the betterment of school hygiene, medical inspection, the establishment of open-air schools, etc.—yet it is no doubt a vulnerable point of attack in the eradication of this disease.