This is seen in the establishment of laboratories by boards of health in cities and states in which knowledge obtained by exact investigations can be made of direct service to the people; in the medical inspection of schools and factories; in promulgating laws directed against conditions which affect health, in the extension of hospitals, and in divers other ways.

The idea of public service and of returning to the people in an effective way some of the results of their labor also underlies the large donations which have been given for the creation of special laboratories and institutes in which, through research, greater knowledge of disease may be obtained and made available.

The researches which have been made on the nutrition of man and the nutritive value of different foods are of great importance, and this knowledge has not yet begun to be applied as it should be.
There seems to be a balance maintained between the restriction of disease by prevention and the increased influence of social conditions which are in themselves factors of disease.

Preventive medicine seems to have made possible, by restricting their harmful influence, the increase in industrialism, in urban life, and in the intercommunications of peoples.

The most important aid in the future to the influence of preventive medicine must be the education of the people so that the conditions of disease, the intrinsic and the extrinsic causes and the manner in which these act, shall all become a part of general knowledge, and the sympathy of the people with health legislation and their active assistance in carrying out measures of prevention may be obtained.