146 THE BACTERIAL DISEASES OF PLANTS 



it in Germany on winter stock (Matthiola incana). Recently 

 ]\Iiss Nellie A. Brown, of my laboratory, has found it to be the 

 cause of a serious disease of the highly prized Chinese cabbage 

 {Brassica petsai L. H. Bailey) grown in the United States. 

 There is no reason, however, to suspect that the disease was 

 imported from China since it is everywhere in the United 

 States. The writer did not succeed in inoculating this disease 

 into beans. Infection occurs chiefly through the water-pores 



Fig. 80. Fig. 81. 



Fig. 80. — Early stages of water-pore infection on inoculated cabbage leaves: 

 A, extrusion of fluid from the water-pores leading to infection; B, appearance of a 

 leaf margin about 3 weeks after water-pore infections. 



Fig. 81. — Vertical section through water-pore region of a cabbage leaf show- 

 ing bacteria under a stoma. 



on the leaf serratures (Figs. 80 to 84), but may occur also 

 through wounds (Fig. 85). Sometimes the leaves wilt, but 

 wilting is less conspicuous than in the cucurbit wilt (No. I), 

 In the attacked leaf parts there is a conspicuous brown vena- 

 tion (Figs. 84, 85) often in a yellow parenchyma. The stem 

 bundles are also browned (Figs. 86, 87). It is not a soft rot, the 

 attacked leaves becoming dry and leathery rather than wet- 

 rotten, unless soft-rot parasites are also present. The black 



