72 o. isHii 



produced different kinds of colonies when grown on agar plates, 

 some being opaque and others transparent; in addition there 

 were also differences in their contours, some having irregular 

 outlines while others were round with smooth edges. Further- 

 more some colonies were small and others large. 



APPEARANCE OF SPONTANEOUSLY AGGLUTINATED COLONIES ON 



AGAR PLATES 



Plating many stock cultures upon two per cent agar plates 

 we have found two distinct types of colonies. The first of these 

 presents a smooth surface and a regular outline, and is not 

 spontaneously agglutinated. The other type shows a much 

 heavier growth, has a rough svirface, is irregulariy round, with 

 a serrate border and is much more transparent, both at its cen- 

 ter and border, than the first type of colony. That most of the 

 colonies of this second type undergo spontaneous agglutination, 

 can be noted by means of the low power microscope or hand 

 lens. In some instances, upon sub-culturing, certain strains of 

 those colonies which previously had been transparent became 

 opaque and vice versa; or an organism originally producing small 

 colonies produced large ones. These points of differentiation are 

 not so important as those relating to the outUne of the colony 

 and smoothness or roughness of the surface. The available 

 space for growth on the plate as well as the rate of growth, appear 

 to influence these characteristics. 



SPONTANEOUS AGGLUTINATION IN BROTH CULTURES (TABLE 1) 



Steinhardt, Teague and IMcWilliams found in broth cultures 

 of Bad. typhosum, which underwent spontaneous agglutmation, 

 flocculi or pellicle formation as contrasted with a uniform, cloudy 

 growth of other organisms. Smith and Reagh showed that a 

 broth culture of Bad. ideroides became clear after spontaneous 

 agglutination had occurred. 



We have observed spontaneous agglutination of Bad. typho- 

 sum, Bad. paraiyposum A and B, Bad. enteritidis, Bad. dysenteriae 

 and Bad. coli in pepton water, glycerol broth and glucose 



