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Mr. E. W. A. Walker. 



may be that a strain, which for a period (possibly for years) has yielded 

 excellent eu-agglutinable cultures, begins, for totally unknown reasons, to 

 give bad agglutinators. Sometimes these " bad " cultures are really more or 

 less dys-agglutinable. They probably contain a fairly large proportion of 

 ■dys-agglutinable individuals, so that, in a series of agglutination tubes, a 

 haze of opacity remains in those which should show total agglutination, and 

 the series tails off in a succession of " traces " instead of ending sharply. 

 Such a culture cannot be used for standardisation. At other times they are 

 self-agglomerated (self-agglutinated, auto-agglutinated) growths, which may 

 refuse to shake up into uniform suspensions. These difficulties can usually 

 be overcome by repeated daily subculture in bouillon for 14 days or more, as 

 recommended by Dreyer. But that plan does not always succeed. In such 

 cases a eu-agglutinable culture can often be obtained without much diffi- 

 culty by the methods already described, working from the deposits if the 

 culture was dys-agglutinable, or from the supernatant fluids if it was in a 

 self-agglomerating phase. In confirmation, it may be stated that Dr. A. D. 

 Gardner, to whom I communicated the method, informs me that on one 

 occasion it enabled him to obtain a good agglutinator from an otherwise 

 intractable culture. A similar separation can also sometimes be obtained by 

 mere plating and selection of colonies. 



B. paratyphosus A., B. paratyphosus B., B. ccvtrycke B., B. enteritidis (Gaertner), 

 B. coli, B. dysenteries (Shiga), B. dysenteries (Flexner), V, W, X, Y, Z, 

 Vib. cholcree. 



All these organisms were tried during the summer and autumn of 

 1920, at the same time as the earlier experiments with B. typhosus, 

 by the method of successive subcultures in diluted agglutinating serums. 

 A dys-agglutinable culture of B. paredypliosus A. was readily obtained ; one 

 of B. pareityphosus B., with greater difficulty, owing chiefly to a strong 

 tendency to revert when brought into ordinary bouillon culture. B. coli 

 also yielded a dys-agglutinable non-motile phase. B. ccrtrycke and B. enteri- 

 tidis (Gaertner), were found very difficult to manage. 



On one occasion only, in each case, was a non-motile dys-agglutinable 

 bouillon culture obtained in a test-tube. Massive subculture in flask 

 seemed to lead to immediate reversion to the motile eu-agglutinable phase, 

 and some of the cultures were hyper-agglutinable as compared with standard 

 cultures when tested with standard serum. In another attempt, made with 

 the same strain of B. enteritidis (Gaertner), during 6 weeks of this year 

 (1921), though non-motile or largely non-motile colonies were several times | 



