PURE CULTURES. \"J 



plate 4 than from the same plant a week later (fig. 10). One would also be more 

 certain of pure cultures by plating from the interior of the plant at A, B, or C, 

 rather than at X or Y. 



The judgment of experienced bacteriologists as to the pathogenic nature of 



Fig. 10* 



an organism may to a certain extent be accepted in absence of full proof, but 

 only for the time being. Nothing is absolutely certain which has not been experi- 

 mentally demonstrated. 



*FiG. 10. Datura mctelloidcs, inoculated by needle-pricks with Bacterium solanacearum. The 

 same as plate 4, but six days later, i. e., on July 28. 



