446 BACTERIAL DISEASES OF PLANTS 



FIG. 341. A crown-gall teratoma on common tobacco showing an abnormal 

 organ, shoot (?), leaf (?). Probably a stem, because its vascular system comes off 

 the normal vascular cylinder and is itself an irregular cylinder. This growth 

 is a blunt, cylindrical, curved, horn-like, white body, pale greenish at the swollen 

 base and bearing 20 abortive green or greenish leafy organs (shoots), most of which 

 are borne on longitudinal seams as if on rudiments of decurrent leaf wings. Pos- 

 sibly it is a modified leaf as it does not arise in any leaf axil. The largest and green- 

 est of the leafy outgrowths are 3 at X along a seam which extends to the top of the 

 horn. Stem inoculated in the leaf axils November 26, 1916, with sub-culture 

 of colony 2 (Bacterium tumefaciens) from carnation witch broom (see Fig. 337). 

 Photographed January 24, 1917. X 4. 



