Leichtenstern describes the subsequent spread of the disease: “The transfer of the disease by ships which played such an important role in the first epidemic appeared to be insignificant in 1891, in spite of the fact that influenza was present in many of the English colonies. The third real epidemic spread of influenza was a true pandemic which began in the autumn (October) of 1891 and lasted through the whole winter until the spring of 1892. It involved all of Europe and North America and spread to all other lands, but here again the geographic distribution followed no rule. There was no spread of influenza from a central point, no continuous spread following lines of communication, and there was no longer an early predominance in the cities lying on the lines of communication or in the larger cities and commercial centers, as had been the case in the first epidemic. In England in 1891 the first outbreaks occurred frequently in country districts. The epidemic raged nearly four months in the northern part before it finally reached London in May. The same was true of Australia. “One peculiarity of the recurrent epidemic lay in the much more contagious character of the disease and the remarkably greater mortality. In Sheffield the mortality in the recurrent epidemic was greater than in the pandemic, even though the epidemic picture was that of a primary wave.” By way of summary of our knowledge of the primary and secondary spread in general up to the epidemic of 1918, we may enumerate the more important characteristics: 1. Occurrence of true pandemics at wide intervals, primarily intervals of several decades. 2. Indefinite knowledge and conflicting evidence regarding site and manner of origin. 3. Apparent transmission chiefly or entirely through human intercourse. 4. Rapid spread over all countries, the rapidity roughly paralleling the speed of human travel. 5. Rapid evolution of the disease in the communities where outbreaks occur, with nearly equally rapid subsidence after several weeks’ duration. 6. Apparent lack of dependance on differences of wind or weather, seasons or climate. 7. Generally low mortality in contrast to enormous morbidity. Variation in the incidence of disastrous secondary infections. 8. Tendency to successive recurrences at short intervals. SECTION II. INFLUENZA EPIDEMICS SINCE 1893. In this section of our report we will describe with as great accuracy as our sources of information will permit, and in as great detail as space will allow the events which have led up to the epidemics of 1918–20 and the various phases of the epidemics themselves. Points of similarity with previous epidemics will be made obvious; the differences, when of significance, will be described and studied in detail. OCCURRENCE SINCE 1893.