The virus of lhuman influenza was isolated in 1933 and 1934, followingb intranasal instillation of tlhroat washings in ferrets, by Smith, Andrewes, and Laidlaw (1, 16). In the late summer of 1934 their evidenee was first corroborated in thle United States in thle laboratories of the Rockefeller Institute (8) by the recovery of a strain of the same vir'us from an epidemic in Puerto Rico. Since that time several strains and types of influenza virus have been isolated, and from materials from patients in epidemics in 1932 an(d later years the predominant type of virus has been determined (7). Altlhough simplified methods of concentrating aii(I purifying influetiza virus lhave been developed (9), it is not practicable at present to ise virus findings on individual patients as anl aid in diagnosis, as is (lone with throat cultures in diagnosing diphtheria. However, if a considerable number of patients in an apparent influenza epidenmic are tested for influenza virus, it can l)e stated whetlher the epidemic was predominantly due to virus A, A', B, or some unknown type. Of the epidemics since 1932, the nmost common predominant etiologies have been viruses A and A', and inore frequently the latter since 1940. Another development which must have profoundly affected the trend of influenza and pneumonia mortality was the (liscovery anil 1se, of the sulfonamides, peniicillini, and otlher newer cliemotherapies in the treatment of the disease. The literature on this subject is extensive but a few studies on pneumonia aniong humnians may be cited. Some early reports on sulfanilamide therapy on human cases of pneumonia were made by Heintzelman, Hadley, anid M[ellon (11) and Price (12); on sulfanilamide an(d serum treatment bv Price and Myers (13), and oIn seruim treatment by Rogers and Goochl (1). Obviously, studies of influenza prior to 1933 and 1934, when the Virus was first isolated, were rather largely descriptive of the nature of the outbreaks, including explosiveness, extent of the epidemic in terms of deaths in excess of normal seasonal expectancy, cases reported
