106 BACTERIA IN RELATION TO PLANT DISEASES. 



Stem above the basal cut slit longitudinally for a distance of a foot, the nodes are yellowish brown, 

 and the internodes have bright yellow bundles. There are 2 small ears; both show infection at the 

 base of the cob, and in the husks of one are numerous water-soaked spots, from which the bright 

 yellow bacteria have oozed to the inner surface. 



LXVI. Cut 3 inches from the base, there is a yellow ooze from nearly every bundle. Slit the 

 basal part longitudinally; the three nodes are brown; the greenish-white internodes show distinctly 

 yellow bundles. Plant cut i foot higher, there is a bright yellow ooze from many of the bundles at the 

 upper cut. Slit this foot-long piece longitudinally; it contains 2 nodes which are yellowish brown; 

 the yellow stripes (yellow bundles) in the greenish white internodes are conspicuous. Cut 8 inches 

 below the male inflorescence, there is a yellow bacterial ooze from about 30 bundles as far up as this 

 (29 inches from the base of the stem). Slit this upper, 14-inch, portion longitudinally; the nodes are 

 distinctly yellow and show a yellow ooze; the greenish white internodes bear conspicuous yellow 

 bundles. In some places the bacteria have oozed out of the bundles and formed yellow spots in the 

 parenchyma of the internodes. On examining microscopically the bacteria are seen to be in nearly 

 or quite every bundle 4 inches below the male inflorescence (33 inches from base of stem). The male 

 inflorescence was broken over about i inch above the point from which the section was cut. There 

 were 2 ears, both of which showed infection at the base. The bacteria are single or joined end to end 

 in twos or fours. They are enormously numerous, and I fail to see any distinct motility. They seem 

 to be rather more than twice as long as broad. 



LXVII. Three abortive ears and one ear with kernels. The three small ears show slight infec- 

 tion at the base, while the large ear shows distinct yellow bundles at the base of the cob, and all the 

 husks when cut near the base show a yellow ooze from the bundles. When cut 3 inches from the 

 base, the stem shows a yellow ooze from nearly every bundle. The basal part split longitudinally 

 shows 3 brown nodes, with many yellow bundles in the internodes. The first 3 nodes above the basal 

 cut are also brown, while the remaining nodes of the stem show a yellow bacterial ooze. There are 

 numerous yellow bundles in the lower internodes. The disease apparently runs out (hand-lens) at 

 the node next below the tassel. 



LXVIII. Cut 3 inches from the base: There is an immediate yellow ooze from nearly or quite 

 every bundle. Cut the stem a foot higher : There is a yellow ooze from nearly every bundle. Slit 

 the basal portion longitudinally; the 2 nodes are brown; the greenish white internodes contain yellow 

 bundles. One large and one small ear. Both show numerous bundles, from which yellow bacteria ooze ; 

 these are near the base of the cob. The bundles of the leaf-sheaths also show yellow ooze. Slit the 

 middle portion of the stem longitudinally; the white internodes contain numerous yellow bundles and 

 in places the bacteria have escaped from the bundles into the parenchyma, forming small pockets 

 from which they ooze out on section as yellow slime. Cut 20 inches farther up, the infection is incon- 

 spicuous at this height; there are a few bundles plainly diseased in the leaf-sheath surrounding the 

 stem, but I can not see any in the stem. Six inches lower, just under the node, there are at least 40 

 bundles infected. This is at a distance of about 2.5 feet from the ground. The disease is present in a 

 number of the leaf -sheaths half-way up the stem. About a foot below the tassel at least 20 bundles in 

 the stem show the yellow bacterial ooze, and a number of the bundles in the surrounding leaf-sheath 

 also show the yellow ooze. The bacteria have oozed out into the parenchyma to a greater extent in 

 the internodes of this plant than in any other plant examined. They occur as small bright yellow 

 spots in the white pith. 



LXIX. A large plant with 2 large and 2 small ears. The bacteria are present in a leaf-sheath 

 half-way up the stem. They are also present in the base of the blade of the same leaf. The 2 smaller 

 ears show yellow bacterial ooze from the bundles at the base of the cob. With a hand-lens I can not 

 detect any bacterial slime in the leaf-sheath next higher up, nor in the one above that, but I presume 

 a microscopic examination would show its presence there. (Later: The microscopic examination was 

 made and showed that the bacteria were present id 6 bundles of this leaf -sheath.) Nothing certain as 

 to any infection in the 2 larger cobs. Not examined with compound microscope. Cut main stem 3 

 inches from the base; there is an immediate yellow ooze from nearly or quite every bundle 150 or 

 more. (Examined later under the compound microscope and counted 184 bundles, of which at least 

 1 50 were infected.) Slit the stem longitudinally the whole length, a distance of only 3 feet ; the basal 

 3 nodes are brown, the next 3 are yellowish; the internodes are greenish white, with bright yellow 

 bundles and yellower spots in the parenchyma between the bundles where the bacteria have formed 

 small cavities. The infection continues distinctly up to the last internode but one, where it becomes 

 less conspicuous and is not visible under the hand-lens. As in all the plants thus far examined, the 

 bacteria become less abundant toward the top of the stem. This plant bears numerous good roots, 

 as in case of nearly all the rest. The basal part slit longitudinally shows 3 brown nodes and whitish 

 internodes with yellow bundles. I examined in cross-section a dozen or more roots quite carefully. 

 If there is any infection whatever, it is not visible under the hand-lens except in the case of one root 

 from which there is a slight yellow ooze. None of the roots show any external signs of disease. 





