sinuses of the head, the meninges, the lungs and other parts of the respiratory tract. It is not fundamentally necessary that a toxine producing organism be present in overwhelming numbers before it can be accepted as the cause of the toxemia. Nor, on the other hand, must we have toxemia every time the organism is found. The prevalent idea among bacteriologists would appear to be the reverse of what I have just stated. It would, indeed, be extremely difficult to make bacteriological diagnoses of a great many of our diseases, where the etiological factor is well established, if these conditions were required. We do not do so, for example, in diphtheria, examinations of stools for typhoid, nor in infections with the tetanus bacillus. We recognize carrier cases of meningococcus, B. typhosus, hemolytic streptococci and many others, without detracting seriously from their importance in definite types of infection. Formerly the specificity of the different bacteria for definite disease processes was very rigid, but today we interpret more broadly the finding of gonococcus in endocarditis, the meningococcus in bacteremia, B. typhosus in osteomyelitis, streptococci and pneumococci in all manner of infections and many other bacteriological results. True it is that the various bacteria show predilections for attacking certain tissues, but the varying susceptibilities bring about the greatest variations in the manifestations of these infections. The B. influenzæ is not confined to the causation of severe pandemic or epidemic influenza, but includes in its field purulent bronchitis, meningitis, sinusitis, conjunctivitis and many other pathological processes. It further should be recognized as a relatively frequent cause of complications in measles and other diseases. _Infections of the Respiratory Tract_ The disease influenza is primarily an infection of the respiratory tract. It varies from one of the most acute and fatal diseases we know of through all grades of severity—from chronic infections lasting over years to the familiar three or five day fever. This graduation is to be found more or less marked in all our bacterial infections, but would seem to be not generally recognized or appreciated as occurring in infections with the influenza bacillus. That Pfeiffer was dealing with one phase of the disease when the influenza bacillus was discovered does not invalidate the results of numerous workers which have been added since then.