COBB'S DISEASE OF SUGAR-CANE. 



not appear in the first stages of the disease, and the writer is inclined to think that the 

 reddening of the bundles is a later stage than the yellowing. Valeton makes the same 

 observation respecting Sereh. Plates poured from bundles showing red ooze yielded only 



Fig. 7.* Fig. 8.t 



the yellow colonies of Bacterium vasculanun, indicating that this red ooze was due not to 

 red bacteria, but to a red reaction on the part of the host-plant. Perhaps the formation 

 of this pigment would not be as noticeable in all varieties of sugar-cane as in "common 



*FlG. 7. Cross-section of a leaf-sheath of inoculated sugar-cane No. 4. showing bacterial occupation of bundles 

 and of intercellular spaces of the parenchyma. This is not an inoculated leaf, but one higher up and infected from 

 the vascular bundles of the stem. There was abundant l>acterial ooze on the inner face of this sheath (right side). 

 Slide 466 K 1 2, upper row, second section from the left. Drawn with Zeiss 8 mm. apochromatic objective, No. 12 

 compensating ocular, and Abbe camera. 



tFio. 8. Inoculated cane-plant No. 9 at the end of 10 weeks, showing the doubled-up terminal bud pushing 

 through sidewise, owing to the fact that the leaves above it were gummed together by the bacteria. Buds at base 

 pushing abnormally. 



