292 



GENERAL MICROBIOLOGY 



seedlings, petioles of cabbage seedlings, potatoes, etc., 

 may be used for this exercise. For what other plants is 

 B. carotovorus pathogenic? 



2, Thoroughly wash the root, or vegetable to be in- 



FIG. 62. Crown Gall Produced by Bact. tumefaciens. (Orig.) 



oculated. Two or three vegetables of one kind should be 

 employed. 



3. Disinfect a spot about 2 cm. in diameter with 1 : 500 

 mercuric chloride and rinse with sterile water to get rid 

 of disinfectant. Drain off excess moisture on sterile filter 

 paper, handling vegetable with sterile forceps. 



4. Puncture the disinfected area on one vegetable with 



