106 VARIATIONS EST PATHOGENICITY [OH. vn 



produced were indistinguishable from those produced by the 

 strain isolated from the spinal fluid. 



Whatever aspect of pathogenicity, therefore, we study, the 

 same feature becomes apparent namely, that this property 

 of bacteria is, like others, subject to variation. 



VARIATION IN OTHER CHARACTERS OF BACTERIA. 



In the foregoing pages variations in morphology, ferment- 

 ing power, virulence and pathogenesis have been discussed in 

 detail. There remain many more characters of bacteria to be 

 considered such as their viability, their staining properties, 

 their power to produce indol and to liquefy gelatin, their ag- 

 glutination reactions and many others. It would be easy 

 to illustrate the variations these characters also undergo 

 under different conditions. Many examples will be found in 

 Chapter II. 



