CLASSIFICATION OF PNEUMOCOCCI ill 



found at least three subgroups in Type II. Sugg, Gaspari, Flem- 

 ing, and Neill 1354 in 1928 described a peculiar strain which, while 

 possessing a partial antigenic relationship to typical Type III 

 Pneumococcus, had distinct immunological properties of its own. 

 In a later study of this same strain, Harris, Sugg, and Neill 595 as- 

 certained that in rabbits this culture, related to but not identical 

 with Type III, evoked better antibody (agglutinin) response than 

 did Type III organisms, but in mice the Type III strain gave rise 

 to a higher degree of protection against the homologous organism. 



Other serological variants were found by Clough (1919). 239 Her 

 nine strains were agglutinated by Type I, II, and III antiserums. 

 From the I and II serums, by absorption, two strains removed the 

 agglutinins and tropins for the homologous cultures only and not 

 for typical I or II organisms or for other atypical pneumococci. 

 Absorption of the serums with homologous cultures removed ag- 

 glutinins and tropins for all the atypical strains. The phagocytic 

 and agglutinative reactions of the atypical organisms in monova- 

 lent serums indicated that, in general, the strains were serologi- 

 cally distinct, although in a few cases they exhibited some interre- 

 lation. The special atypical monovalent serums showed no activity 

 with Type I, II, or atypical Type II pneumococci. 



Another atypical strain of the heterogeneous Group IV was de- 

 scribed by Pockels, 1101 who thought that its growth was sufficiently 

 individual to warrant his calling the strain Pneumococcus planus. 

 This organism has not been further identified. Gordon, 543 testing 

 fifteen strains of Group IV by cross-agglutination and agglutinin- 

 absorption, sorted them into three groups and eight separate het- 

 erologous strains.* 



In England, Armstrong 19 was able to identify subgroups among 

 Type II pneumococci which corresponded to Avery's IIA and IIB 

 and, by means of agglutinin-absorption, divided Types I and III 

 into subordinate groups of limited specificity within the main type 



* For a review of serological classification as it stood in the year 1922, and 

 for a very readable discussion of the theory of antigens and antibodies, the 

 reader is referred to Eastwood's 3 ^-* two papers published in that year. 



