102 BACTERIA IN RELATION TO PLANT DISEASES. 



of the green husk, making bright yellow spots (small cavities). The bacteria are traceable in the cob 

 of this ear as far as the kernels, but not distinctly into them. Two inches from the base of the stem 

 the internode shows diseased vessels. The lower 2 nodes are brown and the internode between shows 

 yellow bundles. The 5 nodes next above this basal portion are also brown. The infection is clearly 

 visible in the internodes to a distance of 2 feet above the ground as yellow bundles and is traceable 

 still farther up the stem, but becomes less abundant; the disease (yellow slime in the bundles) dis- 

 appears in the second node below the tassel. 



XLI. Plant 4 feet high. Cut 3 inches from the base, internode shows many yellow bundles. 

 Basal part slit longitudinally, its 3 nodes are brown; the internodes contain black and yellow bundles. 

 One large ear and two small ears, each with bright yellow bacterial ooze visible in the bundles. It 

 extends visibly to the base of the cob in the larger ear. The 3 nodes next above the basal cut are 

 brown. Three nodes next farther up are distinctly yellow from the presence of the bacteria. The 

 disease runs out into the sheath of a large leaf half-way up, but I can not detect the bacteria with 

 any certainty in the nearly dried up blade of this leaf (hand-lens). Disease plainly visible in inter- 

 nodes half-way up the stem in the form of bright yellow bundles from which yellow slime oozes 

 when they are cut. 



As in all the cases hitherto observed, the infected bundles become less numerous or less distinctly 

 diseased as one proceeds from the root to the male inflorescence at the top of the plant, showing quite 

 clearly that the infection must have proceeded from the base of the stem upwards. In this plant also 

 there are places where the bacteria have oozed out of the bundles and affected the surrounding par- 

 enchyma of the internodes. These spots or pockets in the parenchyma are bright yellow. 



XLII. Plant 3 feet high, male inflorescence white, leaves dried, stem green and sound externally. 

 Cut 3 inches from base, the internode contains many bundles from which there is a distinctly yellow 

 bacterial ooze. Basal part slit longitudinally, the two nodes are brown. 



The browning, as in all cases hitherto reported, is central and does not extend entirely out to the 

 periphery of the stem. The hard outside portion immediately around this brown area is sound (plate 

 10). The basal internodes show numerous yellow bundles. The nodes farther up are brown or 

 yellow lower ones brown, upper ones yellow i. c, from presence of Bad. stcwarli. The internodes in 

 the middle of the stem show some brown bundles and many yellow ones. One large ear and two 

 smaller ones, each infected at the base. The bacteria are not distinctly visible in the middle leaves, 

 and in the stem they disappear, so far as can be determined with a hand-lens, about a foot below the 

 male inflorescence. 



XLHI. Plant 4 feet high, leaves dried up, roots plentiful and sound externally. Basal part of 

 the largest ear shows distinct infection, but not very abundant. Stem cut 3 inches from the base: 

 Numerous yellow bundles in the internode. The plant has a great many healthy roots. (All the 

 plants are well provided with roots.) Base slit longitudinally shows the 2 nodes brown and the 

 internodes with brown and yellow bundles. There are 3 small ears and a large one. One of the 

 small ears is diseased at the base. The other three appear to be sound. Three of the nodes in the 

 main axis next above the basal cut are brown. The fourth one, which gave rise to the large ear, shows 

 bright yellow bacterial ooze in one place. One of the nodes next farther up is distinctly yellow with 

 bacterial ooze, and those still farther up show no distinct evidence of the disease. The internodes half- 

 way up the stem are diseased, but the yellow ooze is much less abundant and in fewer bundles than 

 farther down the stem. Some of the leaf -sheaths half-way up the stem have diseased bundles. 



XLIV. Plant 4 feet high, male inflorescence white and dry, leaves dried up, roots abundant 

 and sound externally. Cut 3 inches from base, there are many yellow bundles in the internode. 

 Slit longitudinally through this basal part, there are 2 brown nodes connected by white internodes 

 striped with yellow bundles. The 4 nodes next farther up are brown. The next 3 are in an earlier 

 stage of infection, i. e., yellow from the presence of the bacteria, but not yet brown. Four of the 5 

 small ears are infected at the base. The middle internodes of the stem have numerous yellow bundles. 



XLV. Plant only 14 inches high, leaves and male inflorescence dry, roots sound in appearance. 

 Cut 3 inches from the base: Internodes contain brown bundles. Slit longitudinally, the nodes are 

 brown and the internodes contain both brown and yellow bundles; farther up the nodes are yellow 

 and the internodes greenish-white with yellow bundles. Visible infection disappears toward the top. 



XLVI. Plant 3 feet high, roots sound externally, male inflorescence white and dried out, all 

 leaves dry. Good-sized cob, basal part infected. As in a number of other instances, the bacterial 

 infection is most abundant on the periphery, on the lowest, outermost side of the ear. Stem cut 3 

 inches from the base, the internode shows numerous yellow bundles. Sliced longitudinally, the 

 base of the stem shows 3 brown nodes and yellow stripes in the white internodes. The inner husks of 

 the ear are badly infected (in the bundles), and in many places (100 to 200) the bacteria have made 

 their way into the parenchyma between the bundles in quantity so as to show as yellow masses. The 

 bacteria have also oozed out on the inner side of the husk, in several instances, in yellow masses, wet- 



