PLATE XX 



Teratoid crowngalls produced in tobacco by inoculating Bacterium tumefaciens 

 (isolated from a hop tumor several years ago and passed through a sunflower in 1915). 

 The inoculations were made by needle pricks in the axils of the lower leaves (under 

 the arrows), at which places small leafy tumors developed. These sent tumor strands 

 into the midribs of both leaves (L L) and later secondary teratoid tumors {S T T) 

 burst through and covered the top of the midrib. From the upper leaf axil also a 

 tumor strand developed, passing upward through 5 intemodes and then out into the 

 midrib of a leaf for several inches, giving rise at frequent intervals to tumors bearing 

 leafy shoots (teratoid elements) and to others free from them. This tumor strand 

 {T St) was not on the surface of the stem, as might appear from the photograph, but 

 was near enough to show through as a translucent band about 2 mm. wide. Time, 

 26 days. 



