20 



BACTERIA IN RELATION TO PLANT DISEASES. 



Others, as might be expected, state that they have observed no evidence of deterioration 

 in the Rappoe cane. Arrowing is considered by one of these men as a sign of early ripening. 

 Another had observed 15 years before that the cane would arrow where the land was dry 

 and sandy and nowhere else on the plantation. 



To the following question : Have you noticed any ten- 

 dency toward premature blossoming in sugar-cane attacked 

 by your bacterial gum-disease? Cobb replied as follows: 



No; I can not say that I have noticed any earlier blossoming, 

 but it might have occurred without my having noticed it. The 

 chances of blossoming are reduced by the method of growing 

 cane, the object being to prevent blossoming. Nevertheless 

 the tendency might be there and, as the actual blossoming is 

 prevented by the harvest, the tendency might escape notice. 

 There is a tendency to what might be termed premature ripening 

 of the cane, that is, the stalk takes on the ripe colors at an earlier 

 stage. This of course is a feature of many plant diseases. 



^00 mm 



Fig. 13.* 



Fig 1 4.f 



*FlG. 13. Longitudinal section of stem of sugar-cane inoculated February 6, 1903, showing red stain inan affected 

 bundle. There are no bacteria in the part here shown except the vague outlines of some at level of X. Slide 310 (20, 

 lower left-hand corner. 



fKiG. 14. Petri-dish poured-plate of Bacterium vascularum in nutrient agar, stock 716. This plate was made 

 directly from yellow slime taken from the interior of "gummed" sugar-cane received from New South Wales in October 

 1902. Plate poured Oct. 16, photographed Oct. 30 by transmitted light. The organism grew slowly (temperature 

 about 23 C). 



