VIII, B, 6 Barber: Dysentery Bacilli 551 



in a hanging drop on September 9. After twenty-four hours' 

 growth, among many thousands of normal cells, some were found 

 which grew chain-like with elements much more plump than the 

 normal. Six of these variants were isolated, and of the six 1 

 grew. This, transferred to agar, grew apparently normally, but 

 the cells showed a morphology decidedly different from that of 

 the parent type (Plate I). 



For confirmation, various other similar races were isolated 

 from the stock, and all showed the same general characteristics. 

 Not only was the morphology of cells grown on agar different, 

 but, when transferred to ordinary bouillon, adherent masses, 

 instead of the usually separate elements, were formed. These 

 masses, sinking to the bottom, left the supernatant fluid clear, 

 while the controls remained nearly uniformly cloudy. After cul- 

 tivation at room temperature for over one year and passage 

 through 54 agar transfers, the clumping tendency was as marked 

 as before. The irregularity in the form of the cells became less 

 marked after some months, and finally the culture became in this 

 respect like the control. 



The new race showed no fermentative characteristics different 

 from the normal. This variation seems to be of the same general 

 type as that previously described by me^" as occurring in Bac- 

 terium coli, where long chains, isolated, gave rise to races mor- 

 phologically different from the parent stock. 



Strains of dysentery which present new morphological charac- 

 teristics have been described by several authors, the new strains 

 proceeding from aberrant colonies rather than from selected 

 aberrant cells. Kruse, Rittershaus, Kemp, and Metz " found 

 secondary colonies in dysentery and pseudodysentery cultures, 

 which, when transplanted to bouillon, showed a growth having 

 a tendency to clump. Baerthlein-* has described morphologic- 

 ally aberrant colonies not only in dysentery but in cultures of 

 cholera vibrios and of typhoid, paratyphoid, and Gaertner's 

 bacilli. In both the Shiga-Kruse and the toxin-free types of 

 dysentery bacilli, he obtained colonies which differ in form of 

 colony, morphology of bacilli, and in agglutinability from the 

 parent types.^^ 



' Loc. cit. 



-' Zeitschr. f. Hyg. u. Infectionskrankh. (1907), 57, 418. 

 ''Centralbl f. Bakt. etc., Ref. (1911), 50, Beiheft, 128. 



' Baerthlein, Arbeit, a. d. kais. Gesundheitsamte (1912), 40, 433. 



