Public health research is divisible into two categories: first, the fundamental sort, which seeks to discover and formulate the natural laws which underlie a great many phenomena relating to health subjects; and second, the practical sort, which attempts to solve some immediate and pressing difficulty. Both kinds are necessary. Enormous advances along a wide front follow the first kind, of which no better example can be cited than those which resulted in Pasteur's generalization regarding microorganisms. Those in the second category may be compared to the capture of a trench or a redoubt in military operations, but they have the advantage of greater assurance of permanency and of being repeated by other workers at other places.

The separate activities under public health research work are so numerous and varied that it would be entirely beyond the scope of this article to attempt an enumeration. Possibly some reference to the classes of personnel employed on this work may give an idea of its range. The United States Public Health Service, for example, maintains scientific workers of the following kinds: medical officers specializing in a great variety of clinical, laboratory, and field investigations; sanitary engineers, equally diversified in interests; chemists - organic, analytical, physical, physiological, biological, industrial, etc.; biologists - including various specialists in microbiology, parasitology and helminthology, entomology, planktonology, and limnology; physicists specializing in various branches of radiology, illumination, electricity, mechanics, etc.; bacteriologists and pathologists; sociologists, psychologists, and psychiatrists; epidemiologists, statisticians, and mathematicians. These and other scientists, with their technicians and assistants, make up a body of some three hundred persons. The library personnel, also, must not be forgotten, since it is essential in public health work to keep up with the literature in one's specialty.

Control operations of public health are a function of its official organizations which occupy most of their time. The "control" refers to the diseases which should be checked or eradicated. Naturally, the first step is to know where and in what numbers the cases of various disorders are occurring. A bureau of vital statistics is required to collect, classify, and arrange this material. Reports of communicable diseases are secured from practicing physicians, and are supplemented from various sources, such as the records of school and industrial absenteeism and the reports of visiting nurses. Then there are the birth and death statistics to be recorded and analyzed. From this mass of material, suitably tabulated and graphed, the health official of a great city, for example, is enabled to watch the progress of disease and the effect of his efforts from season to season and from year to year. To meet the needs as they arise he has a number of bureaus or sections devoted to inspection and sanitation, the control of communicable disease, visiting nurse activities, hospitalization, the health of children and mothers and of industrial workers, the operation of water works, sewage disposal, milk control, and a host of other activities.

For carrying out these measures the health official must be provided with legal authority, and in many instances this extends to police authority over the activities and liberties of citizens. It is customary in these days, however, to exhaust the possibilities of persuasion before resorting to the exercise of police powers. Persons who are innocently or otherwise maintaining a menace to the public health are usually given a chance to mend their ways voluntarily before the compelling force of authority is exercised. The health official realizes full well that his duty is to all the citizens, and that a friend and a convert is always an asset. There is unfortunately a very fair proportion of persons at large who, according to the verdict of the majority of their fellow citizens, are wrong-headed about these matters, and so obstinately so that there is no recourse other than to compel them to do certain things in the public interest.

Education of the public has long been a slogan amongst health workers. It is possible that the slogan is less heartily voiced in recent years than it was formerly. On the other hand, it is believed that actual public education in health matters has improved in the meanwhile. The fact is that the slogan was in some instances merely a confession of weakness. When a lack of success was encountered in health work, there was a tendency to blame it on the ignorance of the public and to insist that the public be educated. In many instances, however, it was found that the knowledge which it was so ardently desired to transmit to the public was quite unimpressive, threadbare, and none too solid.

Nevertheless a great deal of good work has been done, if not in ' 'educating'' the public, at least in bringing the aims, programs, and needs of health work before it for a sympathetic appraisal. Practically every known method of publicity has been used; the poster, the handbill, the lecture, movie and radio, leaflets, pamphlets and booklets without number. Health information has been included in the curriculum of the schools and colleges, even including, to some extent, the medical colleges.

The opinion may be expressed, however, that something far more radical must happen to American educational methods before the general public is ready to receive the information which the public health profession desires to transmit. It is difficult to visualize this as taking place immediately or within a generation or so, since what is needed is less the acquisition of some of the facts of health and disease as mere disconnected information, than an orientation toward environment which is in accord with the revelations of physical science. It requires no more than a casual familiarity with the product of our schools and colleges to assure one that such an orientation does not at present prevail throughout more than a small proportion of the graduates. However well grounded they may be in those branches which are mysteriously designated the humanities, they are, in general, extremely ignorant of humanity, its relations to other life, to its own racial history, and to the problems of successful living. Although possibly proficient in some major subject of science, it is seldom that they have acquired a well-rounded view of relationships. Since it is manifestly impossible to raise up a generation composed principally or largely of persons well grounded in all branches of science, it may well be wondered what is intended in this discussion. What is intended is the inculcation of a different way of looking at things, less geocentric and less egocentric, which is the refined product of scientific thinking, and is, after all, the recognized true meaning of education.