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 





'^1^ 



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 Bactcriutn. solanacearuin after 5 days at 20°C. in 

 + 10 nutrient beef pejitone gelatin. Organism isolat(>d fiuni 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.), 



