Classification of Pneumococcus IV. 31 



With one serum of group F, a strain from a pneumonia case, 

 forty-nine cultures have been tested and only the homologous 

 strain has been agglutinated in a high dilution, that is, through 

 I in 160. Three other strains agglutinated by this serum (two 

 from normal mouths, and one from a lung culture of a lobular 

 pneumonia case at autopsy) formed a subgroup, agglutinated 

 through 1 in 20 only by this serum, through 1 in 160 by immune 

 serum of one member of the subgroup. The latter has no agglu- 

 tinative action on the type cultures even 1 in 2. 



Of one hundred and five cultures tested against one serum of 

 group G, three have been agglutinated, two of them from post- 

 operative pneumonia cases, and one from a normal mouth. One 

 of the post-operative pneumonia strains was agglutinated by the 

 patient's serum. 



Immune sera of groups H, I, J, and K, have been on hand only 

 a short time, but although few tests have thus far been performed 

 with these strains, two members of each group have been found. 



L represents a single strain, recovered from the sputum of a 

 post-operative pneumonia case and agglutinated by the patient's 

 serum. Immune serum of this strain has been tested with one 

 hundred and fifty-three different cultures and has agglutinated the 

 homologous strain only. This is apparently not a common mouth 

 inhabitant. 



Conclusions. 



Pneumococcus IV strains isolated from pneumonia sputum 

 and normal mouths seem to fall into a large number of groups. 

 However, a considerable proportion of them are classifiable. 

 Twelve fall into one group, ten into another, seven into another, 

 five into another. Several other groups of from two to four have 

 appeared and it is probable that further tests will result in an 

 enlargement of these groups. 



It seems possible that the agglutinative properties of strains 

 may change. 



