

430 BACTERIAL DISEASES OF PLANTS 



in a cool box and make frequent transfers (once every 3 weeks). 

 It lives longer in milk and bouillon than in agar. 



Bacterium tumefaciens is cross-inoculable on a great variety 

 of plants, e.g., using strains cultivated from the daisy and hop 

 we have produced galls on more than 40 kinds of plants belong- 



FIG. 328. Crown gall on Paris daisy. Result of a pure-culture inoculation. 

 Section of a tumor showing lignin deposited out of place, i.e., on the walls of 

 three cells of the large-celled petiole parenchyma (Cortex). Stained with methyl 

 green and acid fuchsin. 



\.\>y ' * 



ing to 18 families, as follows : daisy (2 sp.) tomato, potato, tobacco 



(3 sps.), oleander, cabbage, cauliflower, turnip, radish, beet, car- 

 rot, grape, clover, peach, almond, raspberry, apple, pear, carna- 

 tion, hop, Coleus, Citrus, Impatiens (2 sps.), Opuntia, Persea 



beginning; epidermis pushed up. (2) Longitudinal section through a young un- 

 ruptured secondary tumor in a petiole. Normal tissue under pressure at either 

 side and bulging. Result of a pure-culture inoculation. (3) A part of 2 enlarged. 

 The round spots are nuclei in the cells of the tumor. The bacteria are invisible. 

 (4) Cross-section of a petiole showing the central leaf -trace converted into a second- 

 ary tumor which has not yet ruptured : tumor -strand in the center, beyond which 

 is a whorl of wood-wedges not well lignified (the lignified parts are stained dark), 

 beyond these cambium and then phloem. Beyond the tumor is the large-celled 

 leaf parenchyma, which is compressed and bulging. Result of a pure-culture 

 inoculation on the stem. Normal leaf-traces above and below. 



