In view of the fact that recurrences have followed closely in the wake of all former influenza epidemics, and with the hope of stimulating concerted investigation of preventive measures, the American Public Health Association (57), at its meeting in Chicago in December, 1918, appointed a committee to outline “a provisional working formula, based on the facts and opinions brought out at the meeting.” A summary of the opinions as taken from the report of the committee is given here. They reported that the disease was probably due to some micro-organism or virus as not yet identified; that while it was known as “influenza,” it was not known to be identical with the disease generally known under that name; that there was no known laboratory method of differentiating it from ordinary colds, bronchitis, etc.; that there was no known laboratory method of determining when a patient ceased to be infective; and that the deaths from influenza were due to secondary pneumonia resulting from an invasion by one or more forms of streptococci, or by one or more forms of pneumococci, or by the so-called influenza bacillus or bacillus of Pfeiffer. Because of the clear and concise manner in which this report brings out the opinions held, at the time, by a majority of the medical profession a portion of the report is given here _verbatim_. “Evidence seems conclusive that the infective micro-organisms or virus of influenza is given off from the noses and mouths of infected persons. It seems equally conclusive that it is taken in through the mouth or nose of the person who contracts the disease, and in no other way except as a bare possibility through the eyes by way of the conjunctivæ or tear ducts. “If it be admitted that influenza is spread solely through discharges from the nose and throats of infected persons, finding their way into the noses and throats of other persons susceptible to the disease, then, no matter what the causative organism or virus may ultimately be determined to be, preventive action logically follows the principles named below, and, therefore, it is not necessary to wait for the discovery of the specific micro-organism or virus before taking such action. “1. Break the channels of communication by which the infective agent passes from one person to another. “2. Render persons exposed to infection immune, or at least more resistant, by the use of vaccines. “3. Increase the natural resistance of persons exposed to the disease by augmented healthfulness.” The ways and means of carrying out these principles are many and varied, and it is merely the intention of this paper to put together a sort of digest of some of the more important arguments for and against some of the seemingly more important measures proposed. _Methods Proposed for Breaking the Channels of Communication_