THE DYSENTERY BACILLI 447 



3. Fermenting glucose, mannitol and saccharose 



[Strong (Manila)]. The Strong Bacillus. 



4. Fermenting glucose, mannitol, and maltose (Flexner, 



Harris, Gay, Woolstein). The Flexner Bacillus. 



By agglutination, however, these four cultural types 

 form three groups, for the Shiga strain is agglutinated by 

 Shiga serum only, the Flexner and Y strains by either of 

 the two sera, but not by Shiga serum, and the Strong by 

 its own serum only. The Strong, therefore, remains 

 separate both culturally and by agglutination, but as it 

 has not been isolated anywhere since its discovery in the 

 Philippines, the dysentery bacilli fall into two principal 

 groups, the Shiga and the Flexner-Y. 



The fermentation reactions are not altogether constant 

 and are liable to some variation ; it is stated, for instance, 

 that the original Strong strains now fail to ferment 

 saccharose. Forms fermenting dulcitol or giving a 

 permanent acidity with lactose should probably as a rule 

 be excluded from the dysentery group. 



As regards the Flexner-Y group, by cross-agglutination 

 and absorption tests the Flexner bacilli may be regarded 

 as forming at least four races (designated V, W, X, Z). 

 The Y bacilli also seem to form a distinct race (Andrewes 

 and Inman). On the other hand, the Shiga bacilli form 

 a single serologkal race. 



Other dysentery bacilli are known, inagglutinable with 

 Flexner serum, and formerly regarded as inagglutinable 

 Flexner-Y strains. These are the cause of dysentery in 

 Norway, Sweden, Denmark, and occasionally elsewhere. 

 According to Thjotta and Sonne these constitute a distinct 

 group, which may be termed the Sonne group, serologi- 

 cally entirely distinct from other groups. The Sonne 

 bacilli ferment mannitol, maltose, saccharose after some 

 days, and occasionally lactose (but not within the first 

 twenty-four hours). Indole is not formed. This group 



