Yet another drawback is the _apparent wide susceptibility_ to the disease. Were individuals definitely immunized by one attack the proportion of susceptibles would be lessened, their concentration in a population would be decreased, and the probability of their being exposed would be proportionately diminished. An additional difficulty is that after an epidemic has once become prevalent, we must combat not only the virus causing the disease but also the _secondary invaders_. Epidemiologic work has shown that _crowd gatherings_ are instrumental in the spread of influenza. The density of population has not been as definitely proven to be a factor. Crowding, however, does play a part. Close crowding in communities must facilitate the spread, but pandemics of influenza were known before the great metropoleis existed. _Hygienic conditions_ play their part in the etiology. Finally, in the presence of every serious epidemic we must also combat the _tendency to panic_ in the population. _Anticipatory or preventive measures._—It is erroneous today to speak of measures for the prevention of influenza in a community. We cannot prevent the disease. At most, we can anticipate the occurrence of an epidemic and take precautionary measures by which the spread and the severity of the disease may be minimized. First and foremost comes _education_. Education of the public, of the medical profession and of health authorities. “Scare headlines” in the newspapers during epidemics should be discouraged. Health cartoons are of value, but when they express only partial truths they cannot but do some harm. General education in hygienic methods and in a knowledge of the spread of contagious diseases has already been most productive. Many methods by which the public intelligence could be reached are as yet untried. A daily paper in Boston devotes two columns a week to a discussion of public health problems, under the title of “The Clinic.” The statements appearing in these columns are nearly always the truth and are not exaggerations. There are discussions of recent scientific work of interest to the reading public. As has been emphasized by Carnwath, a page devoted to methods of maintaining the health of the community would probably be of more immediate value than are the many pages devoted to financial statements, “such as the price of Mexican Eagles or of Peruvian Corporation Preference.”