326 



BACTERIAL DISEASES OF PLANTS 



still marked. Experiment repeated in 1919 with the same dis- 

 tinct differences (Fig. 258). 



On steamed potato cylinders standing in water there is at 

 first a thin, pale yellow, wet-shining growth, which soon becomes 

 copious and entirely fills the fluid, making it solid. The color 



FIG. 249. Agar-poured plates of Bacterium malvacearum showing appearance 

 5 days after exposure (on ice) of the right half to bright sunlight for 2 minutes: 

 A. Bacteria isolated from Turkestan cotton in 1909; B. Bacteria isolated from 

 Arizona cotton in 1914. 



is then Naples yellow to wax-yellow (Ri), becoming brownish 

 with age. The potato grays more or less, and the starch is con- 

 sumed (see No. II and No. VIII). Experiment repeated in 

 1915 using the Arizona organism with the same result. The 



