Studies in Bacterial Variability. 



67 



obtained on agar plates from serum bouillon cultures, transference to bouillon 

 invariably led to immediate reversion. 



Vib. cholerce. — No dys-agglutinable phase has been obtained at present in 

 this vibrio. 



All the foregoing organisms show a tendency to the formation of a 'pellicle 

 in serum-bouillon culture. B. typhosus, occasionally only and very delicate ; 

 B. paratypJwsus A and B, and B. coli, fairly often and well-marked ; 

 Vib. cholerce, frequently ; B. certrycke and B. enteritidis (Gaertaer), very 

 frequent and very heavy, often appearing to contain as much growth in the 

 pellicle as in the deposit at the foot of the tube after 48 hours. These state- 

 ments apply to cultures made in narrow agglutination tubes. 



B. dysenteries (Shiga) yielded a dys-agglutinable culture after eleven 

 passages in serum-bouillon of 1 in 4 dilution. 



B. dysenterice, (Flexner), V, W, X, Y, Z. — These five strains of Flexner 

 dysentery gave interesting results after six passages through 1 in 4 bouillon 

 dilutions of their appropriate serums. Bouillon cultures were made in flasks 

 from the sixth passages, and subsequently formolised and diluted to standard 

 opacity. V, W, and Z cultures were dys-agglutinable ; X was not perceptibly 

 altered ; and the Y culture possessed markedly increased agglutinability, 

 being four times as agglutinable as the standard culture against which it was 

 tested. Of the three dys-agglutinable cultures, Z gave no agglutination at 

 all in 1 in 25 standard Z serum at the end of 4 hours in the water-bath, and 

 no more than a trace minus at the end of the subsequent 24 hours at room 

 temperature. W gave trace minus (tr — ) at 1 in 25 after 4 hours, trace 

 plus (tr +) at 1 in 25 and trace (tr) at 1 in 50, 24 hours later. V, on the 

 other hand, though giving no reading as high as trace plus (tr +) in 

 any dilution, showed traces of agglutination in every tube up to 1 in 1000, 

 thus reaching the same actual end-point with its " traces " as did the corre- 

 sponding standard V culture, which gave totals up to 1 in 250, standard (s) 

 at 500, and trace minus (tr — ) at 1000. 



The discussion of the relation of these dys-agglutinable and well-agglutin- 

 able forms of bacteria to the K and S forms recently described by Arkwright 

 (loc. cit.), and the description of their morphological and other characters, is 

 reserved for a future occasion. 



Summary and Conclusion. 



1. Evidence has been brought forward that in the enteric and dysenteric 

 groups of bacteria dys-agglutinable and hyper-agglutinable forms or phases 

 occur, and can be produced experimentally by the methods described. 



