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Scientific Proceedings (107). 



conditions the effect of the crown gall organism and the neoplastic 

 growth on the host can be kept under observation for an extended 

 period. Drenching rains and destructive insects are avoided and 

 very often other parasitic and saprophytic fungi. In this way and 

 in such plants as Ficus elastica it is possible to show definitely 

 whether and in what degree the crown gall has an effect upon the 

 adjacent normal tissue of the host. 



It was found that Bacterium tumefaciens inoculated into the 

 apical internode of the branches, into the leaves or main stem of 

 the rubber tree, Ficus elastica, stimulates the development of a 

 neoplasm in the region of inoculation of a benign or malignant 

 nature. The crown galls so formed, in this plant, are of two 

 kinds, one in which growth is uniform and appears to be a swelling, 

 the other is the characteristic convoluted type indicating a peri- 

 pheral growth of isolated nodules. The early stages in the develop- 

 ment of the crown gall in Ficus elastica does not interfere with the 

 nutrition of the plant as a whole nor does it interfere with the 

 growth of the inoculated branches. The crown gall in Ficus 

 elastica after a number of months of active growth becomes hard 

 and dry and finally dies. This is associated with the differentia- 

 tion of the tissue which converts the gall into a mass of paren- 

 chymatous cells and nodules of woody fibers. The central portion 

 of the crown gall which generally lies near the wood cylinder 

 disintegrates. 



The invasion of the stem by the new growth does not destroy 

 the entire conducting system of the stem, yet that portion of the 

 stem above the gall dies as well as considerable portion of the stem 

 below. Cultures made from pieces of the crown gall and stem 

 above and below the gall yield only a shizomycete which in appear- 

 ance is not unlike Bacterium tumefaciens and which when inocu- 

 lated into the stems of young geraniums and rubber plants produce 

 crown galls in the region of inoculation. It is altogether possible 

 that substances of the disintegrating crown gall or products of the 

 crown gall forming organism are carried into the circulation of the 

 stem and are responsible for the progress of the death of the stem 

 from the gall upward and downward. The death of the plant 

 due to crown gall is at least suggestive of the death caused by the 

 invading and disintegrating malignant growths in animal cancer. 



