40 



O. ISHII 



Formalin prevents spontaneous agglutination, but does not 

 interfere with agglutination by specific immune sera; it does, 

 in fact, increase the agglutinating reaction, when used with 

 specific serum. 



It has been customary to add formalin as an antiseptic, or to 

 prohibit the growth at certain times of the cultures of the colon- 

 typhoid group, which were to be used in conducting the' agglu- 

 tination test. This method was adapted by Loele, who used 

 2 per cent formalin, while Porges, Coles, Bass and Watkins, 



TABLE 1 



Standardization of formalin concentration in plain broth culture media to prevent 

 spontaneous agglutination. {Cultures twenty-four hours at 37°C.) 



tj: 5, complete; 4, almost complete; 3, weak; 2, very weak; 1, trace; 

 0, negative agglutination. 



Buxton and Vaugham, Roily, and Asser used 1 per cent, Widal 

 0.67 per cent, Garrow, Chick 0.1 per cent; Neisser, Proscher, 

 Lion, Martineck, Ehrsam, Flatau and Wilke, and Selter also used 

 formalin and showed, that it had a tendency to slow down or 

 dinunish the reaction. 



Dreyer has made an especially careful study of the use of 

 fonnalin. He found that 0.1 per cent formalinized broth cul- 

 tures agglutinate more actively than those without formalin, 

 and that 0.5 to 1 per cent formalin cultures agglutmate less 

 actively than those without formalin. 



