85 



Distribution of the Commoner Antigenic Components. 



Complete serological classification of my strains of B. influ- 

 enzae has proved to be impracticable owing to the multiplicity 

 of their antigenic components. I have classified them, therefore, 

 into groups according as one or other of the commoner antigens 

 revealed in Table 4 is present in a strain in significant amount. 

 In the case of many strains more than one of the three common 

 antigens can be detected : such strains I have classified as 

 " mixed." There remains a large residuum in which these 

 antigens are absent or present in insignificant amount : these 

 strains I have classified as " individual." 



The presence of the group antigen has been taken as estab- 

 lished when agglutination of the strain with the production of 

 permanent clumps, visible to the naked eye, has occurred in the 

 group serum diluted 1 in 100. A sufficient number of strains (20) 

 have been tested for absorption of agglutinin to make this 

 assumption reasonable. The group sera employed have been — 

 for group I serum Lister 3, for group II serum L 10, for group III 

 serum B.S. 6. 



The majority of the strains classified have been tested also 

 with the other nine sera of Table 4 : the results have confirmed 

 the grouping : in a few cases close serological relationship has 

 been demonstrated with strains such as Fechger in which the 

 predominant antigen is one of relatively rare occurrence ; such 

 strains have, of course, remained in the " individual " group. 



It must be clearly understood that the classification shown in 

 Tables 6, 7 and 8 is not a classification into types such as exist in 

 the case of the pneumococcus, nor even into such as have been 

 found in the meningococcus. It indicates only the extent of the 

 distribution of certain antigens in the species as found at the 

 present time. In many of the strains which have been grouped 

 under the headings I, II, III and " Mixed " the dominant antigen 

 has probably not been detected, being a complex peculiar to 

 the strain itself : that is to say, if sera were prepared with such 

 strains they would agglutinate the homologous bacilli to a much 

 higher titre than any of the strains selected as representative of 

 the group. Strains of this kind differ only from those grouped 

 as " individual " in possessing a certain amount of one or more 

 of the three antigenic components which have been found to be 

 of more general occurrence. 



Table 6. 



Distributions of the Commoner Antigens among Strains isolated 



from Sputum and Lung from April, 1920, to December, 1921. 



