66 



BACTERIA IN RELATION TO PLANT DISEASES. 



rod and 14 plates poured at 41 to 38 C, after inoculating very copiously six 3 mm. loops 

 in one instance. In other canes it was found alive at the end of a year. 



Tubes of bouillon inoculated November 9, 1903, and kept at room-temperatures were 

 still cloudy on March 17 (129 days), but a transfer from one of them did not cloud bouillon. 

 In beef-agar stabs kept in the refrigerator at io to i5C.the cultures were alive at the 

 end of 7 months 10 days. Under similar conditions another culture was dead at the end of 

 7 months 18 days. Here the temperature may have been a few degrees higher, i. e.,i2 to 

 16 C. Another tube inoculated 14 days later and subject to the same conditions was alive 

 at the end of 6 months 21 days. Two other tubes of the same lot were dead at the end of 6 

 months 12 days. Three other stab-cultures were dead at the end of 7 months 3 days. 



The organism was 

 alive in cultures on potato- 

 agarattheendof 7 months, 

 but they were probably in 

 the cold box. 



The organism was 

 alive in 6 potato cultures 

 at the end of 35 days (room- 

 temperature about 25C), 

 but probably a large part 

 were dead, as the transfers 

 to fresh potato-cylinders 

 grew slowly. 



On March 21, 1905, 

 ten cultures on potato in 

 the refrigerator at io to 

 1 4 C. since October 6, 

 1 904 (166 days) were tested 

 for vitality, transfers being 

 made to potato-agar 

 (streaks) . Two grew well ; 

 two feebly in small portions 

 of the streak ; and the rest 

 did not grow. Of the two 

 which grew well, one came 

 from cane plant No. 40 

 and the other from cane 

 plant No. 42. 

 The organism has been found alive in milk cultures 54 days old ; also in some 75 days 

 old. Milk is a suitable culture medium for this organism. 

 The organism is killed by sunlight (fig. 37). 



RESUME OF SALIENT CHARACTERS. 



POSITIVE. 



Parasitic in sugar-cane, clogging the vascular bundles with a bright yellow slime and 

 forming cavities in the soft parenchyma; frequently comes to the surface of the inner leaf- 

 sheaths as a viscid slime. Surface colonies on +15 standard nutrient agar pale-yellow, 



Fig. 37. 



Tig. 37. Bacterium vascularum in an agar-poured-plate after exposure of right side to bright sunlight (on ice) for 

 30 minutes. Plate poured and exposed January 19, 1906. Photographed January 26, 1006. The few bacteria which 

 grew into colonies on the exposed side of the plate were sheltered, it may be presumed, from the direct action of the 

 sun by other overlying bacteria 



