192 



BACTERIAL DISEASES OF PLANTS 



of elements, chains, filaments, pseudozoogloeae, motility on mar- 

 gin of a hanging drop (best seen by flooding a young agar- 

 streak culture with sterile water and taking a drop from the 



a 





\ . 



FIG. 134. Flagellate rods of Bacterium solanacearum: a, Medan III from 

 Sumatra (Courtesy of J. A. Honing), b, North American organism (from North 

 Carolina). Each X 1000. 



FIG. 135. Stab cultures of Bacterium solanacearum after 5 days at 20C. in 

 + 10 nutrient beef peptone gelatin. Organism isolated from Baltimore Tropaeo- 

 lum. No liquefaction. 



top of the water after an hour or two), presence and distribution 

 of flagella which are hard to demonstrate (try van Ermengem's 

 silver-nitrate method, Lo wit's method, Pitfield's stain, etc.), 



