STEWART'S DISEASE OF SWEET CORN (MAIZE). 99 



tissues and slight indications of small cavities. Some of the bundles in this longitudinal section 

 were distinctly yellow from the presence of the bacteria. The smaller stem slit in the same way 

 showed the same thing, except that there was more browning and injury at the base of the stem. 

 Some of the bundles were distinctly yellowed by the bacteria and others were browned. In the 

 bases of the badly diseased leaves, in some places, the bacteria had escaped from the vessels and 

 had made yellow pockets in the neighboring parenchyma, just as Bacterium hyacinthi does in 

 the bulb-scales of the hyacinth (vol. II, plate 20). Material was saved in alcohol. The disease 

 in these plants is the typical " bacteriosis " of sweet corn as it exists on Long Island. Eight 

 Petri-dish poured plates were made from each plant into acid (mulberry) agar, but the organism 

 did not grow. 



V. No record. 



VI, VII, VIII, IX, October 7 : The external appearance of each of these four plants was the same, 

 viz, a sound green stem and sound roots, but shriveled leaves, the reason for which was not apparent. 

 On cutting, the vascular system of each stem was found badly diseased, the vessels being filled with a 

 yellow slime. The bacteria were traced up the stems for many centimeters, but the bundles in the 

 first decimeter of the stem were most fully occupied. The tissues were most badly diseased in the 

 extreme base of the plant, i. e., in the first two or three nodes and short internodes, the same being 

 that part of the stem nearest the point of union with the particular leaves which had been inoculated. 

 In the internodes of this part of the stem a few of the bundles were brown, but most of them were bright 

 yellow from the presence of the bacteria. In the extreme base of the stem there was a very decided 

 browning of all the tissues ; in two cases this browning also included the next two nodes. On cross- 

 section of the stems the bacteria oozed from the bundles as beads of yellow fluid (fig. 41). 



X, XI, XII, XIII, October 10: Four additional suspects were brought in for examination. In 

 each the staminate inflorescence was dead. The tallest of these plants was 3.5 feet. The average 

 height of the plants in the field on this date was 3 to 3.5 feet. A few were much shorter and a 

 few were over 4 feet high. Numerous bundles in the stem of each one of these four plants contained 

 the yellow slime of the bacteria in abundance. This was visible to the unaided eye in bundles at a 

 distance of more than a foot from the root. On longitudinal section the first two to three nodes of the 

 stem were decidedly brown, the internodes being white. 



Plants XIV to XXIV were brought in and examined on October 14. They averaged 

 3.5 to 4 feet in height. Roots were abundant and sound externally in all. The leaves were 

 more or less shriveled. Several of the plants had small weak shoots coming up from the base. 



XIV. Basal nodes brown, but infection less widely spread and less conspicuous than in the fol- 

 lowing cases. No indication of yellow vessels in the internodes. 



XV. Stem cut 3 inches from base : Numerous bundles from which yellow slime oozes ; also some 

 brown bundles. Stem split longitudinally: Brown nodes, bundles in internodes either brown or 

 yellow ; infection extends far up into the upper leaves; lower nodes of cobs brown within. 



XVI. Stem cut 3 inches from base: To the naked eye one-half dozen infected bundles. Split 

 longitudinally : Basal nodes brown, but only a few of the internodal bundles are infected ; two upper 

 internodes not yellow; all lower internodes are brown. Ear affected with larvae; doubtful if bacteria 

 present. Comparatively little infection of upper part of stem. 



XVII. Basal parts of stem show yellow bundles. 



XVIII. This plant was photographed separately (pi. 8, fig. i). Cut 3 inches from base: Vessels 

 filled with yellow slime. This plant has several little ears coming out near the ground; these are 

 browned in the nodes and yellow (gummed) in the internodes. Specimens of this and other cobs 

 were saved in alcohol. Split lengthwise : Nodes at base brown with yellow bundles in the internodes ; 

 the upper nodes grade from brown into yellow. Infection traced to just below the staminate inflores- 

 cence. On longitudinal section the bundles in the upper internodes show as distinct yellow stripes. 



XIX. Cut plant about 3 inches from base : It has numerous bundles showing the yellow ooze. 

 Cut i foot from the base : Still shows yellow bacteria. Cut 2 feet from base : Still shows yellow bac- 

 teria. The yellow slime appears to be, to a small extent, in the roots close to the stem. On longi- 

 tudinal section, brown in all nodes (7) up to tassel, not in ear. 



XX. Either XX or XXI was photographed separately (pi. 8, fig 2). Cut about 3 inches from 

 root : Numerous bundles show yellow ooze. Brown in nodes at base of stem, where there are also 

 small bacterial cavities. Bundles between the basal nodes are either brown or yellow. Infected at 

 all nodes, the two upper nodes yellow instead of brown. The five basal nodes of the largest ear are 

 yellowish from presence of the organism, and there is yellow slime in the internodal bundles; the infec- 



