STEWART'S DISEASE OF SWEET CORN (MAIZE). 103 



ting its surface. These masses when touched with the finger string up decidedly (i cm. or more). 

 Six of the husks are infected in this way. There are about 180 small bacterial pockets in the par- 

 enchyma of a single husk; in another husk there are more than 100. Specimens of these husks were 

 saved in alcohol and one of the husks was photographed (vol. II, fig. 14) but the contrast is less than 

 in nature. Samples were saved in alcohol from the base of the cob. It is doubtful whether the bac- 

 teria can be traced out into the kernels. The first 2 nodes above the basal cut are brown, several far- 

 ther up are brown with a yellow ooze. The next 4 are yellow. The infection is plainly visible with a 

 hand-lens in bundles 3 inches below the base of the male inflorescence. The middle internodes con- 

 tain numerous bright yellow bundles. The sheaths of the middle and upper leaves also contain yel- 

 low bundles, from which there is a bacterial ooze. The disease is not distinctly visible in the leaf- 

 blades, which are dried up. There is less of the bacterial infection toward the top of the stem. 



XLVII. Plant 4 feet high, roots sound externally, all leaves dry except part of an upper one. 

 Stem on the outside green and sound. Cut 3 inches from the base, there are a great many yellow 

 bundles from which the bacteria ooze out. Basal part slit longitudinally, there are 3 brown nodes, 

 and the white internodes contain yellowed bundles. The plant bears 3 ears, the bases of which are 

 diseased, i. e., have vascular bundles occupied by the bacteria. Above the basal cut 2 nodes are 

 brown, 3 others farther up are yellow from the presence of the bacteria. The middle internodes show 

 distinctly yellow bundles. Organism present in the bases of the middle leaf-sheaths but not very 

 abundant. There are quite a good many places in the internodes where the bacteria have escaped 

 from the bundles and made yellow spots in the white parenchyma. Bacteria are plainly visible in the 

 stem as far up as a foot under the male inflorescence, but not nearly so many vessels are occupied as 

 lower down. 



XLVIII. Plant 4 feet high, roots abundant and sound externally, stem green and normal on 

 outside, male inflorescence dead and white, all leaves shriveled except the uppermost one. Cut 3 

 inches from the base : A great many yellow bundles in the internode. Slit the base of the stem longi- 

 tudinally ; the nodes are brown ; the white internodes contain bright yellow stripes corresponding to 

 the bacterially infested bundles. Farther up 3 nodes are brown and 3 others next higher are yellow, 

 showing when cut a distinct bacterial ooze. The infection extends into the basal part of the male 

 inflorescence. The plant has 3 ears i large and 2 small. The base of each one shows a distinct 

 yellow ooze from the bundles on section. The husks around the ears are also infected, the bundles 

 are yellow and there are yellow spots and water-soaked spots in the parenchyma corresponding to 

 places where the bacteria have oozed from the bundles. The middle internodes of the main axis have 

 yellow bundles, and here also there are yellow spots in the parenchyma where the bacteria have oozed 

 out. The bacteria are not abundant in the middle leaves. 



XLIX. Plant 4 feet high, all the leaves dried out, stem green and sound externally. Bacteria 

 not abundant in the middle leaves. I can not see any yellow slime with the hand-lens on cross-section 

 of the sheaths. Plant cut across an internode 3 inches from the base, there are a great many yellow 

 bundles; in fact, nearly every bundle of the stem shows a yellow ooze. This part of the stem slit 

 longitudinally shows 2 brown nodes connected by white internodes with yellow bundles. The numer- 

 ous roots are sound externally, but some show the bacterial ooze on cross-section near the stem. The 

 roots do not appear to be much infected. The most badly infected node, as in many other cases, if 

 not all, is the basal one. The disease disappears (hand-lens) some distance under the male inflores- 

 cence, perhaps a foot. Above the basal cut 3 nodes are brown, 2 nodes farther up are yellowish, 

 and the middle internodes show yellow bundles in abundance. The plant has 2 ears each slightly 

 infected at the base in the bundles. 



L. Plant 3 feet 9 inches high, good roots, all the leaves dry, stem sound and green externally. 

 The sheaths of the middle leaves are plainly infected in a few bundles. The same is true of the leaf- 

 sheaths up to the top of the plant. They are all more or less occupied by the yellow bacteria. The 

 disease is visible in the stem close under the male inflorescence, that is, i inch under the first branch of 

 it. The yellow bacteria are distinct in the base of all three cobs. Stem cut across an internode 3 

 inches from the base : Nearly every bundle shows a yellow ooze. Slit longitudinally, its lower 3 nodes 

 are brown and the internodes are greenish white with yellow bundles. Above this, 3 nodes are brown, 

 the next 2 are yellow and show the bacterial ooze distinctly. The bundles in the middle internodes 

 are packed full of the yellow bacteria. 



LI. Plant 3 feet 9 inches high, roots sound externally, stem green and sound outside, all the 

 leaves dry. The yellow slime is present in the middle and upper leaf-sheaths, exclusive of the two 

 uppermost. The upper part of the stem for a foot under the male inflorescence appears to be free 

 (hand-lens). Three ears, all badly infected at the base. This infection extends up into the part 

 which bears the kernels, and the bases of a few of the kernels seem also to be attacked (these have 

 been saved in alcohol). Cut stem 3 inches from the base; every bundle appears to be occupied by 

 the yellow slime. Slit longitudinally, the nodes are brown, the internodes white with yellow bundles. 



