36 BACTERIAL DISEASES OF PLANTS 



the United States; Bacterium lachrymans, the organism causing 

 the angular leaf-spot of cucumber (Figs. 6 to 9 and 23 to 26) ; 

 Bacterium aptatum Brown and Jamieson, causing leaf-spots on 

 Tropaeolum and on beet; and some of the lettuce spot organisms 

 (Bacterium viridiUvidumRrown, Bacterium marginale Brown). 



Some species produce gas (chiefly CO 2 and H), liquefy 

 gelatin, consume asparagin, destroy starch, and reduce ni- 

 trates; others do not. Their fondness for sugars and alcohols 

 is quite variable. Some are extremely sensitive to sunlight 

 and dry air (Bacillus carotovorus, Bacillus tracheiphilus, 

 Bacterium solanacearum, Bacterium malvacearum) ; others are 

 remarkably resistant, remaining alive and infectious on dry 

 seeds for a year (Bacterium campestre, Aplanobacter stewarti, 

 Aplanobacter rathayi, Bacterium translucens) . Some are strictly 

 aerobic, others can grow in the absence of air, if proper foods 

 are available. Some are very sensitive to acids, alkalies and 

 sodium chlorid, others are not. Some have wide ranges of 

 growth from 0C. upwards. Some will not grow at or near 

 0C., others will grow at or above 38C. Very few r , however, 

 will grow at blood temperature, certain ones even in plants 

 or on culture media are killed by hot summer temperatures, and 

 none are known definitely to be animal parasites, unless we 

 except Bacterium tumefaciens. My own animal experiments 

 with this organism have been limited largely to efforts to produce 

 tumors in fish and salamanders. Many of the trout died 

 early of what appeared to be septicaemia and from the dorsal 

 aorta of one of these fish the crown-gall organism was re-isolated 

 in pure culture on agar poured plates and with subcultures 

 from one of the colonies crown galls were induced on sugar beets. 

 Other trout have yielded, both in the abdominal wall and in the 

 eye-socket, what I regard as small tumors but no metastases 

 have been observed. According to Friedmann, Bendix, Hassel 

 and Magnus, Bacterium tumefaciens causes a purulent menin- 

 gitis in man and also an ulceration of the intestinal mucosa 

 (Zeits. f. Hygiene u. Infektionskr., April 23, 1915), but Jensen 

 of Copenhagen has contradicted this, having shown that 

 Friedmann's supposed pure culture was contaminated, and 

 Friedmann himself now admits that he was in error. 



