cobb's disease of sugar-cane. 39 



Next clump : 3 young shoots. Sound. Older shoot, very leafy nearly to the base. Must have 

 grown since the date of inoculation. Sound throughout. 



Old shoot, bears label of 67a and 6jb. It is leafless to a height of 6 feet. It is sound throughout. 



My custom is to section top and base and every internode between before deciding. 



Old cane, leafless for first 6 feet. Sound throughout. 



Another clump on same row: 3 young shoots. Sound at the base and above. 



Old shoot, leafless for a distance of 6 feet. Sound at the top; sound at the base. In the second 

 internode above the base there is a red stain in one bundle, which soon runs out ; plant sound otherwise. 



General Remark. All that precedes relates to first (north) row of Cinta. 



Only one plant on this row (No. 63) shows any distinct indications of bacterial infection, 

 and in this the signs are slight and confined to five internodes. They are here, however, 

 beyond any dispute. Having waited some little time there is now a distinct, yellow, bac- 

 terial ooze from the diseased vessels of this stem, which for the most part are central vessels 

 rather than peripheral ones. The nodal infection is most abundant in two of the nodes, 

 which probably correspond to the two inoculated leaves. Mr. Johnston made plates from 

 No. 63, and got numerous, round, yellow colonies of typical appearance. They came up 

 rather slowly. Cultures were saved from six colonies on January 24, and subcultures from 

 three of them were used to make inoculations 106 to 140 of February 9, 1906. 



On January 17 I continued my examination of canes. (Labels misplaced in some 

 instances, no doubt.) 



Caledonia Queen. 



North (inoculated) row: 



Two recent shoots. Very green; leafy; sound inside. Five more young shoots from the same 

 clump, all about 6 to 8 feet high. Sound both externally and within. One more young shoot of the 

 same character. No signs of disease. 



There are three old canes in the clump. The first one bears label No. 77a. It is a tall cane, 

 leafless for the first 8 feet, leafy the next 4 feet. The cane is greenish colored on the surface. The 

 upper leaves do not show any white striping. Some undeveloped leaves around the terminal bud 

 are dead. Shortening the cane several internodes; these dead leaves continue, and are surrounded at 

 this level by five healthy leaves and by the inner living bud. Shortened another 2 feet. Stem 

 sound. Stem continues sound in every internode for a distance of more than 9 feet. There is no 

 indication of disease anywhere in the cane beyond a slight red stain in two of the vascular bundles 

 near the base. 



Another large cane, like the last in external appearance. Terminal bud dead. Some red stain 

 in the central tissues under the terminal bud. This soon runs out and does not look like the bacterial 

 cane disease. Shortened the stem in every node for many feet. There is no indication of yellow or 

 red staining in the vessels, except close to the ground, where two or three bundles have a slight red 

 stain. No disease. 



Third cane : This is also an old cane, not labeled. Sound externally. Leafy only at the top. 

 First red stain in the bundles was met at a distance of 4 feet from the ground. Runs only a short 

 distance. . No other stained bundles were encountered anywhere in the stem, which was sound. 



The next clump: Two young vigorous shoots. Very leafy. Sound externally and internally. 



Three old canes. One bears label 75a, and is leafless for a distance of about 6 feet. This one 

 has two or three red bundles in an internode close to the ground ; 2 feet higher up the leaves are dying 

 at the margin, but are not white striped. Sound at the top within; continues sound for many feet. 

 Every internode cross-sectioned. Continues sound down to the third node from the ground, which 

 has the before-mentioned red stain in a few of the vascular bundles. In the node above this and the 

 node above that one also there is a little red stain. No bacterial ooze. 



Next cane: A few red bundles in the third internode from the ground. The first three inter- 

 nodes are very short. This is an old cane. The leaves are all dead up close to the top. Terminal 

 bud dead. Leafy under the terminal bud. Sectioned every internode from top to base. Sound 

 down to within 3 inches of the ground. At about this height there is a small cavity in the center of 

 the stem and slight red staining of some bundles. Injury very slight. This cavity is in no way con- 

 nected with the surface of the stem at this level, and is due, I think, to the inoculations. 



Third old cane from same clump : No red stain at the base. This is a large cane, naked up to a 

 height of about 10 feet, and has only a few good leaves. Sound within from the top downward a 

 distance of many feet, in fact entirely to the base. 



