78 



while the remainder produced none. No other feature distin- 

 guished the indol-forming strains from those not forming indol 

 and examples of both were found among groups serologically 

 identical. 



Meat water was found useful for the maintenance of the 

 cultures, but, though some strains survived in it for over six 

 months without subculture, others perished more rapidly and 

 subculture was necessary about once a month. 



For the preparation of agglutinating sera rabbits have been 

 used exclusively; they were injected intravenously with living 

 cultures of 24 hours incubation on Fildes's agar suspended in 

 saline. The commencing dose s'hould not exceed 5 milligrams 

 of moist culture, but later much larger doses, up to 80 milligrams, 

 may be given with safety. Satisfactory agglutination titres 

 were usually obtained after six to eight weeks of immunisation; 

 the sera were carbolised and stocked on reaching a minimum 

 titre of 1 in 800. 



Agglutination tests were performed in the water-bath at 

 50° C, readings being made after two hours at that temperature. 

 The bacterial suspensions were made in phenol-saline, about 

 2 milligrams of moist culture being emulsified in each c.c. In 

 a few instances, when the culture agglutinated spontaneously 

 in normal salt solution, it was necessary to employ distilled 

 water for suspensions. In all cases the test quantity was 0'5 c.c. 

 of bacterial suspension mixed with the same volume of serum 

 diluted with saline. 



Frequency of Influenza Bacilli. 



Table 1. 



Isolation of Influenza Bacilli from Pneumonia, tfec, April 1920 to 



December 1921. 



It is evident from Table 1 that influenza bacilli are of frequent 

 occurrence in the tissues and discharges of pneumonia, whether 

 of lobar character or catarrhal. As regards their abundance in 

 the material only an approximate reckoning can be made. I have 

 noted in the case of the 97 positive specimens from lobar 

 pneumonia that 46 gave such , abundant colonies that it might 

 be said that the influenza bacillus was the predominating micro- 



