434 BACTERIAL DISEASES OF PLANTS 



A very good procedure is to flame lightly and pare away 

 the exterior of the tumor with sterile knives, then remove some 

 of the sound-looking interior, plunge for 3 seconds into mercuric 

 chlorid water (1 :1000), then wash for about the same time in 

 distilled water, and crush it thoroughly in a little sterile water 

 or bouillon, using a cold sterile knife -blade on the bottom of 

 a sterile Petri dish (or if great care is taken it may be done 





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t 



FIG. 332. Thin sections of crown gall of the daisy. Tissues stained by means 

 of gold chlorid. Nuclei out of focus are visible in each photograph, and at X 

 there is a Y-shaped rod. 



inside a thick-walled tube in bouillon), using considerable force. 

 The cloudy fluid in the dish should now be pipetted and the 

 mashings scraped and poured into a tube of peptone water, 

 beef bouillon, or autoclaved water, and allowed to stand for 



has ruptured through to the surface. Stem inoculated by needle-pricks in two 

 leaf axils using Bacterium tumefaciens plated from a tumor on hop. Inoculated 

 September 29, 1916. Photographed November 24, 1916. Nat. size. (See next 

 page.) 



