STXJDIES UPON AGGLUTINATION 43 



macroscopically (bj'' means of a hand lens) and microscopically. 

 In the latter case, as many as 15 or more mixtures were exannned 

 at the same time, by transferring a small loopful of each to a 

 square on a large thin glass slide, which had been marked off 

 in squares by means of a grease pencil. 



USE OF FORMALINIZED SPECIFIC SBEUM IN AGGLUTINATION TEST 

 VnTH VARIOUS BACILLI (TABLE 3) 



I have observed that specific serum to which has been added 

 0.2 per cent formalin (final 0.1 per cent) in 0.85 per cent salt 

 solution shows stronger agglutination than occurs without forma- 

 lin. The formalinized senam mixed with an ecjual amount of 

 broth culture after three hours at room temperature, shows 

 strong agglutination with Bad. typhosum and Bad. paratyphosum 

 A, and the same is true, if tubes are allowed to stand over night. 

 Bad. paratyphosum B and the Bad. dysenteriae group show a 

 weak reaction, when examined within three hours; but a stronger 

 reaction if kept over night. Bad. coli shows weak formalin 

 readings after three hours; but if kept over night, the result, 

 with or without formalin, is the same. 



For the graphical agglutination test, we must use non-spon- 

 taneous agglutination bacilli. However, by the addition of 

 formalin, spontaneous agglutination is prevented while at the 

 same time a specific agglutination regularly occurs. As showni 

 in table 3 of the strains of spontaneous agglutination bacilli, 

 Bad. typhosum and Bad. paratyphosum A yielded specially good 

 results; Bad. paratyphosum B showed less influence, while Bad. 

 coli was not influenced at all. When the tests were conducted 

 without formalin, spontaneous and specific serum agglutina- 

 tions usually present the same appearance microscopically and 

 macroscopically, although certain strains of spontaneous agglu- 

 tination bacilli sometimes yield weaker macroscopic reactions. 

 It is evident that spontaneously agglutinating bacilli should not 

 be used for graphical agglutination tests, and that formalin may 

 be used to prevent the complex reaction. 



