STXJDIES UPON AGGLUTINATION 53 



There is slightly less tendencj' to spontaneous agglutination 

 in a broth medium than in salt solution; therefore, I have con- 

 cluded that salt is better for preparing suspensions with agar 

 cultures for Widal test. 



EFFECT OF SODIUM CHLORID ON AGGLUTINATION TESTS (TABLE 7) 



jNIalvoz used agar cultures emulsified with distilled water to 

 avoid chemical changes resulting from sodium chlorid. Weil, 

 working with agar cultures, obtained the same agglutinating 

 reaction, when using cither distilled water, or 0.85 per cent sodium 

 chlorid. Asakawa, Bordet, Chick, Joos, Jordan, and Forges 

 claim that sodium chlorid is necessary for the agglutination test. 

 Dreyer, Krumbaar and Smith used tap water in diluting the 

 serum for broth cultures and the results were better than with 

 sodium chlorid. Chick claims 0.42 per cent sodium chlorid gave 

 good results. 



In my observation 24 hour agar cultures of Bad. iyphosum, 

 Bad. paratyphosum A and B, Bad. dyscnteriae and Bad. coli 

 emulsified with distilled water were agglutinated by specific 

 serum in dilutions of 1:40 or 1:50, as well as when emulsified 

 with 0.85 per cent salt solution; in this case a certain amount of 

 salt contained m the seiiim aided agglutmation. In weak 

 dilutions of 1 : 80 or more, there was no agglutination in distilled 

 water (with one exception), but marked agglutination in salt 

 solution. Evidently at that dilution, the salt content of the 

 serum was not suflficient. Only one strain of Bad. dysenieriae 

 Flexner no. 2, showed constant agglutination in distilled water 

 with a specific serum dilution of 1 : 80. 



Spontaneous agglutination appeared with spontaneous agglu- 

 tinating bacilli in almost every instance, when using either dis- 

 tilled water or salt solution. 



Quantity of sodium dilorid. I have tried various dilutions of 

 salt, varying from 0.05 to 5 per cent, with agar cultures, but no 

 apparent differences were observed in their effect on the agglu- 

 tination reaction. 



It is my conclusion, that only a trace of sodium chlorid is 

 necessary for the Widal test. Since strong solutions are of no 

 advantage, I believe ordinary physiological 0.85 per cent salt is 



