28 BACTERIA IN RELATION TO PLANT DISEASES. 



inoculated plants were given numbers from 27 to 34 inclusive, and the inoculated leaves 

 were labeled 270, 276; 280, 286, etc. For these inoculations tubes Nos. i and 3 of April 27, 

 1903, were used. 



On May 5, 1903, finished inoculating the row of common purple cane. Four plants, 

 Nos. 35, 36, 37, and 38, were inoculated in just the same way as those of preceding day, 

 with one exception; in this case the plant was inoculated in the stem and on one leaf 

 instead of two leaves. This was plant No. 38. Tube No. 4 of April 27, 1903, from poured 

 plate No. 6, of April 16, 1903, was used for these four plants. 



On May 14, 1903, all these plants showed the effects of the inoculation. A distinct 

 discoloration about the punctures was noticed three days earlier and to-day the punctured 

 area is dead, entirely or in great part, on at least eight of the inoculated leaves. All the 

 other inoculated leaves show a marked reddish-brown streaking or spotting in the punctured 

 areas. 



The check leaves show no such discoloration. The punctures on these leaves show 

 simply as small white points. 



On June 13, 1903, common purple cane No. 33, inoculated May 4, 1903, from tube 

 No. 3, April 27, was broken over by accident and brought in for examination. 



It is a shoot about 9 or 10 feet high, with a thick stem and large green leaves, but the basal ones 

 are mostly dead (normal). The inoculations were on the blades of two leaves about midway down 

 the stem, and the pricks were about 8 inches from the sheath on both leaves. The midrib of each 

 inoculated leaf is alive throughout. To either side of the midrib on one leaf are dead areas for a 

 distance of 2 to 3 feet. The other leaf is much the same, except that on one side the dead portion 

 is not so long, perhaps 18 inches. Above this, however, in the green part are yellowish and rusty- 

 yellow dead stripes for a distance of another 18 inches. The outer edges of the sheaths are also dead 

 nearly or quite to the nodes. The ends of both leaves are wholly alive. 



Made cross-section of the sheath at the extreme base and examined it under hand-lens for bac- 

 teria. In one they seem to be present in small quantities, but nothing very definite in either one under 

 the hand-lens. These must be looked at under the microscope to determine the presence of bacteria 

 in the vessels of the inoculated leaves. 



Cut the stem 6 inches above the base. No evidence under the hand-lens of bacteria in the 

 bundles. 



Cut 6 inches higher up and examined again. No bacteria visible in the stem when examined under 

 the hand-lens. 



Cut another 6 inches up. Here, also, the stem appears to be perfectly sound under hand-lens. 



Cut another 6 inches up. The whole stem appears here also to be sound. 



We are now getting into the vicinity where the inoculated leaves join on to the stem. The 

 whole stem appears to be sound. 



Slit the 6-inch segment below the last longitudinally and examined. No evidence of disease. 



Cut another 6 inches up (cross-section). One red bundle in the internode, which is indicative of 

 the disease. Slit this segment longitudinally and examined : Distinct reddening at both the included 

 nodes, but very slight in comparison with the effect on the common green cane. At each node there 

 are a dozen or more red bundles. No ooze. This is a very resistant variety. 



Cut another 6 inches up. No evidence of disease. Slit the stem longitudinally. No evidence. 



The whole upper part of the stem for a distance of several feet was now slit longitudinally and 

 examined for the presence of bacteria. No stain in the bundles; no evidence of disease. 



The disease is confined to the two inoculated leaves, to the two nodes which bear these leaves, 

 and to the immediate vicinity of these two nodes. 



On subsequent examination there seems to be a very light red stain on one side of two nodes next 

 farther up. These also were put into alcohol for further study. 



A microscopic examination showed the bacteria to be present in the bundles of the midrib of the 

 inoculated leaf-blades and in the bases of the leaf-sheaths. 



On August 8, 1903, two of the plants of common purple cane which were inoculated 

 with Bad. vascularum, May 5, 1903, broke off with their own weight. The two plants are 

 Nos. 37 and 38. No. 37 was inoculated in two leaves, while No. 38 was inoculated in one 

 leaf (386); and through various leaf-sheaths into the stem (380). On examination the 

 conditions were as follows: 



