Stallybrass has confirmed Brownlee’s 33-week periodicity and suggests an explanation for the “aberrant” October epidemic. Using periodograms with a 33-week basis, and plotting deaths from influenza and respiratory diseases from January, 1890, through January, 1920, he finds that the most definite 33-week periodicity is shown during the years 1890–99. During this period there is one maximum, when all 33-week periods are superimposed, which occurs at the seventh week of the cycle. Beginning about 1899 a new maximum appears in the nineteenth week of the cycle, which continues to recur until the culminating point is reached in the week ending October 26, 1918. An additional 66 weeks carries the date forward to the first week in February, 1920. The maximum at the seventh week of the periodogram during the years 1899–1913 is greatly diminished from that in 1890–98. The periodogram for 1914–1919 shows clearly both maxima, that in the seventh and that in the nineteenth weeks. We quote Stallybrass in some detail (see Chart XII): “Dr. John Brownlee pointed out that from July 13th to March 1st (the maxima of the summer wave of 1918 and of the spring wave of 1919) is 33 weeks, but that the wave having its crest in this country on November 2, 1918, does not fall into the sequence, leaving one to infer that there were two strains of the influenzal virus in operation. “I supplement his investigation by the weekly deaths occurring in Liverpool during the period 1890–1919 that were ascribed to influenza and to all respiratory diseases. Prior to 1890 there were no deaths attributed to influenza for a number of years. “Closely corresponding with Brownlee’s observations on London by far the most definite periodicity is shown during the years 1890–1899, during which period there is one well marked maximumly at the seventh week of the cycle. During the period 1899–1913 a new maximum in the nineteenth week of the cycle comes into play and continues to recur until the culminating point is reached in the week ending October 26, 1918, a week earlier than in most English towns (Wave III); a further 66 weeks carries one forward to the first week in February of this year, as Brownlee pointed out, and the outbreaks that are being reported in Japan, Paris, Chicago, New York, etc., would show that this strain has punctually reappeared.