194 CROWN-GALL OF PLANTS. 



gall organism in all of his plates, provided nothing was wrong with 

 his culture medium or the galls themselves were not too old. We 

 have not used gelatin media for isolations from galls, but ordinary 

 + 15 peptonized beef-bouillon agar. 



Dr. K. Spisar has also investigated the sugar-beet gall and reaches 

 the conclusion that it is not due to animal or plant parasites of any 

 sort (Zeits. f. Zuckerind. in Bohmen, Prag., Aug., 1910). Bacteria 

 do not occur in all the galls and with those he cultivated out he could 

 not reproduce the disease. He, therefore, ascribes it to wounds, but 

 does not advance any satisfactory reason why it should arise in some 

 wounds and not in others. 



Since the above paragraphs were written we have plated what we 

 beheve to be the right organism from natural tumors on the sugar 

 beet and with subcultures therefrom have obtained small slow-growing 

 galls on beet (PL XXXVI, fig. 1), tomato, and daisy. Most of the 

 colonies tested were noninfectious. 



TUBERCULOSIS OF BEETS. 



In the autumn of 1910 beets from Colorado and Kansas were found 

 commonly attacked by a yellow schizomycete capable of causing 

 cells to proliferate in a nodular growth. On section the attacked 

 parts showed as small, water-soaked, brownish areas (PI. XXXIV, 

 fig. 2). Under the microscope great numbers of bacteria were 

 observed therein and the center of the spot was seen to be disor- 

 ganized into a small cavity. Often the surface of the nodules bore 

 small central radiating fissures (PI. XXXIV, fig. 3). The appearance 

 of these cracks suggested the possibilit}^ that they preceded the 

 infection. In some instances these brownish areas of softening were 

 traced from the galled portion of the beet into the ungalled part. 

 The diseased parts appeared mucilaginous — stringy when touched. 



Tliis disease, which was at first supposed to be crown gall, is only 

 superficially like the latter, because, as in the olive tubercle, the bac- 

 teria are abundant and easily detected and produce areas of softening 

 and central cavities. The disease has been reproduced on sound 

 sugar beets in the department hothouses by pure-culture inoculations 

 (subcultures from poured plate colonies). 



From these artificially produced tubercles the organism has been 

 reisolated and successfully reinoculated into other sound beets. 

 Up to this time cross-inoculations on other plants (daisy, tomato, 

 etc.) have failed. 



Description of Bacterium heticolum n. sp. — This organism, which 

 may be known as Bacterium heticolum n. sp., is a rod with rounded 

 ends, single or in pairs, chains or clumps. Clumps and chains fre- 

 quently occur, especially in pellicles. It measures about 0.6 to 0.8 



213 



