STUDIES UPON AGGLUTINATION 



59 



Certain strains in pepton water cultures showed a slight ten- 

 dency to spontaneous agglutination, while in broth they showed 

 no spontaneous agglutination. The specific agglutinations were 

 weaker in pepton water than broth medium; therefore I consider 

 the latter most suitable for the Widal test with Bad. colt. 



Agar cultures show very weak agglutination, but there is no 

 tendency to spontaneous agglutination with Bad. coli. 



Bad. (hjsenteriae group. This group showed strong specific 

 agglutination in plain broth cultures, it was slightly weaker in 

 pepton water and agar and especially weak in glucose broth; but 

 glucose broth did not show spontaneous agglutination. 



TABLE 9 



Relation of age to specific agglutinating power with non-spontaneous agglutination 



hacilli, grown on broth culture medium 



Key: 5, complete; 4, almost complete; 3, weak; 2, very weak; 1, trace; 0, nega- 

 tive agglutination. 



relation of agglutination power to age of cultures 



(table 9) 



Dreyer claims that cultures more than one day old had a weak 

 agglutinating power with specific serum. My experiments for a 

 period of five days, with Bad. tijphosum, Bad. paratyphosum 

 A and the Bad. dysenteriae group, indicated that cultures on 

 neutral broth medium one day old were agglutinated best, the 

 reactions become weaker each day thereafter. However, I found 

 that one strain of Bad. dysenteriae Shiga no. T showed just the 

 opposite result, the agglutinating power becoming stronger with 

 older cultures over a period of five days. 



