Agglutination tests were carried out with the sera of 14 convalescents and 3 normal individuals. A polyvalent emulsion of strains of the influenza bacillus isolated from our cases was used. The results are shown in Table III. Tubes were incubated at 37.5° C. The results did not indicate anything in the nature of a specific reaction. Dr. Frost carried out this work during the height of the epidemic, but we were unable to continue it further. A short review of the work of others will be found near the end of this paper. Miss Thompson and Mr. Mock studied complement fixation, using the sera of 15 convalescents against an antigen of B. influenzæ. Their results were negative. The antigen appeared to be slightly more anti-complementary than were emulsions of staphylococcus or B. coli. Huntoon also noted this anti-complementary character of emulsions of B. influenzæ. Attempts were made to estimate the amount of complement present in the fresh blood serum of influenza patients. The technique was to use a 1-4 dilution of the patient’s serum, adding measured amounts of this to a 1 per cent. blood emulsion, with 1 unit of amboceptor and determine the smallest amount necessary to bring about complete hemolysis. This test was carried out on eight patients ill for only a few days. The average amount of the dilute serum was 0.181 c.cm. Fifteen patients, convalescent after a moderate illness, gave an average of 0.276 c.cm. Two patients seriously ill with temperatures of 104.3° F. and 105° F. required 0.4 c.cm. to bring about complete hemolysis. We would not like to draw any very definite conclusions where we are dealing with such small fractional differences. This lessening of complement has been noted in other infectious diseases and may be important in the questions of immunity in influenza. Dr. Frost carried out a number of cutaneous tests after the method of Von Pirquet, using a polyvalent, weakly alkaline emulsion of influenza bacilli in 25 per cent. glycerin. Eleven convalescents were tested and none of them showed any local or general reaction. The suggestion that these results may indicate an increase in resistance is discussed in another place. A number of strains of pneumococci which we had isolated from our autopsy cases were differentiated by the agglutination method. Type I was found 3 times; type II, 10 times; type IV, 9 times. Four showed agglutination with both type I and type II sera. Type IV pneumococcus was isolated in one case from the right and left bronchus as well as the lung. In another case the same type pneumococcus was recovered from the lung and pleural fluid. These results are similar to those found by numerous workers. _The Hemophilic Bacteria_