None of these modifications of Pfeiffer’s original work, however, would seem to constitute any valid reason for abandoning the conception of the etiologic importance of B. influenzæ. On the contrary, they are quite in harmony with well-established facts concerning other bacteria which cause infections of the respiratory tract. Such bacteria are frequently found in normal individuals leading a saprophytic existence, are often associated with other disease conditions, and tend to show marked variations in virulence. Since the outbreak of scattered epidemics of influenza beginning in 1915–16, which finally culminated in the pandemic of 1918–19, a vast amount of literature on the subject has appeared. No attempt has been made thoroughly to analyze this, because much of it is not available, much of it abounds in contradictions which it is difficult to harmonize at the present time, and much of it has been written on the basis of insufficient data gathered under the handicap of war conditions by men without sufficient time to undertake special investigation, or it is feared, in many instances, not sufficiently qualified by previous bacteriologic training. The sum and substance of opinion in 1918 would seem to be best summarized by quoting from the published report compiled by the British Medical Research Commission:[20] “Although Pfeiffer may yet furnish reasons why the verdict should not be pronounced, there is already sufficient material to shake the orthodox conception out of its high altar. Two facts stand out prominently: the generally acknowledged, or by some reluctantly admitted, absence of B. influenzæ from organs on postmortem examinations, and the universally recorded findings of diplostreptococci, singly or in association with the Pfeiffer bacillus.” Comment on this opinion will be made in the general discussion at the end of this paper.