106 VARIATIONS IN PATHOGENICITY [CH. vii 



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 op 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. 



