The conclusions arrived at in this paper are based on more than one hundred cases of mastoiditis in private patients which I have observed since the influenza epidemic of 1918. A great many mastoid operations were performed in my clinic at the Vanderbilt Hospital. As I did not perform these operations it was not possible to get a thorough examination of the sinuses in connection with the mastoiditis, so those cases have not been taken into account. The case histories of these patients read so much like the histories of the patients that were carefully examined with respect to their sinuses, however, that it leaves no doubt in my mind that sinusitis was present in these cases to a very large per cent.
Following the epidemic of influenza in 1918 there were a great many cases of mastoiditis. There were also many cases of sinus infection. The association of sinus