_Effect of Addition of Serum on Behavior on Exposure to Air._—The persistence of venous hue of blood exposed to air was noted above. It was observed that the addition of serum from the same blood conspicuously shortened the time required for such blood to acquire an arterial hue. The addition of normal serum was more effective in this respect than pathological serum. Measurements of the rate of absorption of such blood after the addition of serum indicated acceleration of oxygen absorption. From this it would seem that the oxygen transmitting capacity of the serum was diminished. _Effect of Addition of Dry Sodium Bicarbonate on Behavior on Exposure to Air._—The addition of a small quantity of dry sodium bicarbonate to a blood refractory to arterialization on exposure to air enormously accelerated the process, as judged by the color. To what extent the change in color may have been due to causes other than oxygen absorption was not determined. _Comment_ The most significant positive findings were evidence of deficiency of serum oxygen transmitting capacity or rate, and the detection in serum of an absorption band in the red corresponding to methemoglobin. The presence of the abnormal substance giving rise to the absorption band is considered of special interest as indicating abnormal chemical conditions in the blood, rather than material change in hemoglobin oxygen capacity. THE BACTERIOLOGY OF EPIDEMIC INFLUENZA WITH A DISCUSSION OF B. INFLUENZÆ AS THE CAUSE OF THIS AND OTHER INFECTIVE PROCESSES By W. L. HOLMAN, B. A., M. D. _Introduction_ In a study of the bacteriology of a respiratory disease such as influenza, the technical difficulties encountered are very great and must be overcome before we can draw useful conclusions from the results obtained or attempt to determine the etiological factors. The important methods of attacking such a problem include: (1) the study of stained smears and cultures from the various available materials, along with the demonstration of the bacteria in the lesions found in the disease by a study of sections; (2) tests with the various materials to determine the presence of the causative agent, which includes experiments on man and animals and is more inclusive than the mere study of the bacteria isolated; (3) immunological studies of man suffering from the disease, or of man and animals treated with the materials from the disease; (4) pathological, clinical and epidemiological studies linked with the above. Many of the difficulties and sources of error in these methods are manifest to all, but certain points may be indicated as more important in the phases of the work on which I am to report. _General Methods of Investigation_