3° 



Scientific Proceedings (78). 



up of strains that have cross-agglutinated and no interaction 

 between the different groups has been observed. Cross-agglutina- 

 tion tests have been incomplete, only one immune serum being 

 used in some groups. When other immune sera have been used, 

 as in group A, the results have been the same with all, and the 

 strains have agglutinated each other in about the same dilutions. 



All two hundred and thirteen cultures were tested with group 

 A, which consists of 12 strains that have been agglutinated by one 

 or more of the three immune sera of this group. None of these 

 strains have been agglutinated by serum of group B, or by serum 

 of any other group with which they have been tested. Four of 

 them were recovered from the sputum of post-operative pneumonia 

 cases, but as they were not agglutinated by the patients' serum the 

 significance of their presence in the sputum is uncertain. The 

 other eight members of the group were from normal mouths. 



Two hundred and eight strains have been tested with serum of 

 group B (one strain), and ten have been agglutinated. One 

 strain was recovered from the sputum of a post-operative pneu- 

 monia case and was agglutinated by the patient's serum, one was 

 from a bronchitis case, the other eight were from normal mouths. 

 Another strain from a post-operative pneumonia case, agglutinated 

 by the patient's serum and originally agglutinated by serum of 

 group B in a 1 in 40 dilution later lost its agglutinability for this 

 group. Its immune serum has no effect on cultures of group B 

 and a strain agglutinated by its serum is not agglutinated by 

 serum of group B. Two other instances of this sort suggest the 

 possibility of a change in agglutinative properties, though other 

 explanations may be offered. 



Of one hundred and six cultures tested against serum of group 



C, seven have been agglutinated, one from a post-operative pneu- 

 monia case, one from a thyroid abscess, the other five from normal 

 mouths. 



Ninety-seven cultures have been tested with serum of group 



D, and five agglutinated, two from post-operative pneumonia, one 

 from pneumonia, and two from normal mouths. 



One hundred and seventeen cultures have been tested with 

 serum of group E, and four agglutinated, one from post-operative 

 pneumonia not agglutinated by the patient's serum, and three 

 from normal mouths. 



