ANTIGENIC STRUCTURE 691 



this view, Boyd (1940) would classify all strains containing the group antigen, 

 including the Newcastle bacillus, as belonging to the Flexner variety, numbering 

 the different races according to their specific antigen, and would include other 

 strains devoid of the group antigen but biochemically similar to Flexner's bacillus 

 in a new species for which the name of hoyd has been suggested. 

 Thus: 



Old New 



designation designation 



Sh. flexner i V I 



W II 



Z III 



103 IV 



P119 V 



,, ,, Newcastle-Manchester-88 VI 



Sh. hoyd 170 I 



„ „ P288 II 



„ „ Dl III 



It seems to us very doubtful whether the Newcastle bacillus should be included 

 in the Flexner group. Though it may share some of the component antigens of 

 this group, it differs sufficiently in its biochemical characters to justify its being 

 allocated provisionally to a species of its own. 



Boyd's work, which is of fundamental importance, has been substantially con- 

 firmed by Wheeler (1944 a, h) in the United States. Wheeler has extended the six 

 component factors of the Flexner group antigen to nine ; he agrees that Type X has 

 no specific antigen and therefore cannot be regarded as a type ; and he finds that 

 the specific antigen of the W race may be combined with two different sets of group 

 antigen components. 



Weil, Black and Farsetta (1944), neglecting the presence of minor antigens, 

 found no group antigen common to the Flexner types, and therefore proposed that 

 the Flexner and Boyd groups should be regarded as belonging to a single series and 

 classified according to the nature of the primary antigen. Fourteen types were 

 distinguished in this way, labelled I to XIV. Neither Wheeler nor Weil and his 

 colleagues seem to have recognized the form of variation described by Boyd in his 

 strains 103 and P119. Weil worked with a relatively few strains, many of them 

 isolated a considerable time previously, and it would therefore be unwise to lay 

 too much stress on his findings. All that we can say at present is that Boyd's 

 classification, though admittedly imperfect, appears to provide us with the best 

 working model for the serological examination of the Flexner dysentery group. 

 Takita (1937) observed in Flexner bacilli a variation similar to that in 103, but pro- 

 ceeding in the opposite way. It is probable that the discrepancy is apparent not 

 real, depending on the reverse way in which the variants were labelled. 



Before leaving Flexner's bacillus it may be noted that several workers have 

 studied its complex antigenic constitution, particularly Kruse and his colleagues 

 (1907) and Lentz and Prigge (1931) in Germany, and Aoki (1921, 1923) in Japan. 

 Sartorius and Reploh (1931, 1932), Clauberg (1932), Kemper (1933), and Nagakura 

 (1937) have endeavoured to relate the different types established by various 

 workers to each other, but with only partial success. Further observations will 

 be required before we reach a satisfactory understanding of the problem that 

 this organism presents. 



