2 OSCAR TEAGUE 



For the tests fresh transplants of the cultures^ were used after 

 twenty-four hours' incubation. Suspensions of the different 

 cultures in saline solution were prepared of approximately the 

 same cloudiness, and 1 loop of an appropriate dilution of each 

 was inoculated upon plates with different percentages of the Vic- 

 toria blue and upon a control plate containing no stain. The 

 cultures were emulsified and inoculated in lots of four in the 

 order recorded in table 1. 



All of the cultures were subjected to the test on the same day, 

 in order to ensure uniformity of conditions. It was not conven- 

 ient to count the colonies on all the plates at the end of twenty- 

 four hours, so the number was recorded as "numerous" where 

 there was a good growth with obviously little or no inhibition 

 due to the presence of the dye Eighteen cultures of B. para- 

 typhi A., 18 of B. paratyphi B and 11 cultures of B. enteriiidis 

 were employed. Some of these may have been duplicates, hav- 

 ing beon obtained by different laboratories from the same origi- 

 nal strain. The paratyphoid A strains without exception gave 

 good growth even on the plates containing the maximum amount 

 of the stain; the colonies were quite large after twenty-four hours' 

 incubation and the reduction in number as compared with the 

 control plates was usually considerably less than 50 per cent. 

 The paratyphoid B cultures, on the other hand, were almost 

 completely inhibited in their growth by 1 /20 per cent and 1 /30 

 per cent of Victoria blue and some of them were inhibited also by 

 1/40 per cent and 1/50 per cent of the dye; the few colonies that 

 did appear were usually quite small after twenty-four hours' in- 

 cubation. The B. enteriiidis culture behaved on the plates like 

 the paratyphoid A cultures. This seemed surprising, as they 

 resemble paratyphoid B more closely in most of their charac- 

 teristics than paratyphoid A. 



' Stock laboratory cultures of B. paratyphi A and B and of B. enteriiidis were 

 obtained from the New York City Health Department Research Laboratory, 

 the Hygienic Laboratory and the United States Army Medical School in Wash- 

 ington, the Mulford Laboratories, the Museum of Natural History, New York, 

 and from the Department of Tropical Medicine at Harvard. 



