26 BACTERIA IN RELATION TO PLANT DISEASES. 



On cutting across the basal secondary shoots an inch from the stem their tissues seem to be 

 sound (hand-lens). The main axis was then cut open and examined. 



The stem was first cut crosswise in the middle of an internode about 6 inches from the base and 

 then in other places. Some of the vessels are gummy (yellow) and others are distinctly red stained. 

 This red staining, as in the stems previously dissected, is much more conspicuous immediately below 

 a node than it is above a node. A few minutes after cutting, the yellow bacterial ooze was very 

 distinct from many of the bundles. There are cavities in the upper part of the stem. In other 

 places, as well as those first recorded, the red stain is greater just below the node than it is above. 



The middle 3 inches of the stem was slit longitudinally and found to contain a closed bacterial 

 cavity which is 0.75 inch long (estimated) and 0.1875 mcn wide in the widest part, full of pale yel- 

 low slime. 



Slit the basal 3 inches longitudinally and found the disease in the base in the shape of reddened 

 vascular bundles and yellowed ones from which ooze the yellow bacteria. The longitudinal section 

 shows marked red-browning in the vicinity of the nodes and some red vessels in the internodes and, 

 guile interestingly, there is in many cases a red and yellow stain in the same vascular bundle red in one 

 place and yellow in another, showing clearly that the red stain is closely associated with the yellow 

 slime. This material was saved in alcohol and may be identified by the fact that it is cut in the 

 form of thin slabs. 



No. tf.^The height of this plant is about 58 inches to the curve of the top leaves. It is badly 

 diseased, both of the inoculated leaves being dead to the stem and also all of the lower leaves, while 

 the upper leaves are dead at the tips and dried up along one or both sides, but with the midrib living. 

 The terminal leaflet is flabby. The stem is very short. This plant is especially interesting from 

 the fact that 6 inches above the ground the main axis is doubled and twisted and wrinkled crosswise 

 in a swollen mass, the terminal growth being stopped by a drying and gumming of the tissues above 

 the terminal shoot. Lower down the terminal shoot zigzagged and tried to push out sidewise in the 

 same manner as shown in fig. 8. Around this swollen, bulged portion the leaf-sheaths are rusty- 

 brown or pale green and very gummy, the bacterial slime occurring in sufficient quantity to show 

 itself distinctly yellow. The gum does not string up much, but it is sticky to the fingers and so 

 copious that both of my hands are covered with it. The interrupted rusty-brown striping is con- 

 spicuous in the leaf-sheaths that are buried deep in the interior of the shoot, and some very interesting 

 and conspicuous examples of this have been saved in alcohol. The terminal bud is not killed only 

 gummy and glued up and squeezed together (endwise) by the effect of the disease on the sheaths 

 outside of it. 



There is an abundant yellow bacterial ooze from cross-sections of the stem of No. 8. Some of 

 the vascular bundles are also reddened. There is distinctly more reddening of the vascular bundles 

 immediately under the nodes than there is immediately above the nodes. These red vessels are 

 mixed in with those giving rise to the yellow ooze. 



Slit the stem longitudinally. Some of the vessels are bright yellow from the presence of the 

 bacteria and others are red. These are mixed in. Specimens put into alcohol. I am inclined to 

 think that the reddening of the bundles is a later stage in the disease than the yellowing. 



Three cross-sections were cut from No. 6 and one from No. 8 (smaller) and a photograph (X3) 

 made of them together, designed to show the yellow bacterial ooze and also the red bundles (plate i). 



A photograph was also made of a longitudinal section of No. 6, showing the bacterial cavity 

 (fig. 4). On the same negative is a longitudinal section of No. 12 (fig. 1 1), showing red stain in the 

 nodes, and red and yellow bundles in the internodes. 



No. 12. This plant is a little smaller than No. 8. The two inoculated leaves are dead and dry 

 and all the upper leaves are dead, including the terminal one. Lower down there are two partially 

 green leaves. Both, however, are dead at the tip and have dead stripes on the margin. This plant 

 has been allowed to stand too long and some of the outer, dead leaf-sheaths are moldy, which was 

 not the case with either of the others. The inner sheaths are rusty-red spotted, as in case of the 

 others, and there is much bacterial gumming between them. In some cases the spotting is quite 

 brilliant almost a vermilion red. The gumming here also is abundant enough to stick up my 

 fingers very markedly. About 6 inches from the ground there is the same effort of the shoot (terminal 

 bud) to wrinkle, swell, and push out sidewise. Above this swelling (6 inches to a foot) the sheaths 

 surrounding the young leaves are very gummy, and there can be no doubt that this sidewise bulging 

 is due to the gumming and pressure of the outer leaves around the terminal bud. Unwrapping the 

 youngest leaf visible, which was dead at the tip, I find inside of it a younger leaf, also dead at the tip, 

 and the terminal bud is in worse condition than in either of the other plants. The basal buds to the 

 number of seven have begun to push. 



These three stems (6, 8, and 12), stripped of their leaves, were photographed together (fig. 9), 

 and 8 and 12 were photographed together before removal of the leaves (plate 3). 



