126 BACTERIA IN RELATION TO PLANT DISEASES. 



Assuming the kernels to have been the carriers of the organism, the failure of the relatively long 

 soaking in mercuric chloride water would seem to indicate either that the bacteria escaped destruction 

 because they were inside the kernels, or else because they were protected from the action of the germi- 

 cide by being massed together in dried-down hard crusts, the former being the more probable explana- 

 tion. Certainly all those freely exposed on the surface of the kernels must have been destroyed. 



(3) Unselected, unsterilized seed (20 rows) : 



Number of healthy plants, 1,548; number of diseased plants, 156. 

 Total, 1,704; per cent diseased, 9.0. 



Remarks. Of these plants 24 were slightly diseased; 25 moderately diseased; and 52 badly dis- 

 eased. No remarks on the remainder. Comments on some of the badly diseased will be of interest 

 as showing the extent of infection : 



One badly diseased: Bacteria as far up as the cob, and also far above the cob in the top of the stem. 



One badly diseased: Bacteria have oozed through and formed water-soaked yellowish stripes or spots on the 

 pedicel of the cob, and have also oozed through the husks, forming many water-soaked and yellow patches on at least 

 half a dozen inner husks. The bacterial slime was on the inner surface of these husks and also on the kernels. Had 

 photograph made of the husks (fig. 53). A similar oozing through the husks was found yesterday in a plant removed 

 from this same plot to send to Prof. H. H. Whetzel, of Cornell University. Miss Lucia McCulloch examined the slime 

 on the kernels with the compound microscope and found it to be made up of bacteria of the typical sort. These are just 

 as good examples of disease of the cob as any I obtained on the Potomac Flats in 1902. 



Two badly diseased: Every bundle apparently occupied. Infection extends up to male inflorescence, a distance 

 of 3.5 feet from the base, and out into the husks, which are sticky to the touch from the extruded bacterial slime. 



Two badly diseased : Husks badly spotted by the bacteria, and bacterial slime abundant in the stem far above 

 the husks. 



One badly diseased: I find the bacterial ooze bright yellow and viscid on the inside of some of the leaf-sheaths in 

 masses sufficient to scrape up with the knife. It has also oozed out in certain places on the internodes. These places 

 are long, water-soaked, yellowish stripes. Until yesterday I had never seen it forming water-soaked stripes on the sur- 

 face of the internodes. The ears of this plant are also diseased, there being many water-soaked places and many yellow 

 spots on the inner husks. 



One badly diseased: Here the bacteria have formed pockets in the leaf-sheaths, and have oozed out on the surface 

 of the stem as a conspicuous bright yellow slime, which is viscid enough to string out in cobwebby threads. I have just 

 stretched them out 6 inches. 



One badly diseased: Here again the bacteria have oozed from the inner surface of the leaf-sheaths, especially the 

 lower ones, and have formed a great number of yellow pockets in the inner husks. The bacteria have oozed onto the 

 inner surface of the husks in large yellow masses which are sticky. The infection is very striking. Seeing such ears 

 one readily appreciates how impossible it is for the surface of the kernels to remain free from infection. 



One badly diseased: Nearly every bundle at the base of the stem is occupied. The cob is not visibly infected, 

 but the stem near the cob is infected. 



Two badly diseased : The smaller one has no ears, but the inner face of the leaf-sheaths contains water-soaked and 

 yellow spots, and there is a copious yellow bacterial ooze on the inner face of at least three such leaf-sheaths. The 

 larger plant shows no ooze from the leaf-sheaths, but the ear is infected in the same way as those previously described, 

 *. e ., there are numerous yellow spots with bacterial ooze on the inner face of the husks. 



One diseased badly: There are water-soaked stripes on the surface of the internode, but no bacteria have actually 

 come through. 



Four diseased badly : Every bundle is occupied in each stem. 



One diseased badly: Every bundle at the base of the plant is occupied by the yellow slime and bacteria are visible 

 in the bundles at least 3 feet from the ground, probably all the way up to the male inflorescence. Yellow ooze is visible 

 also on the inside of some of the leaf-sheaths and also on cross-section from the base of the cob. 



One badly diseased: Every bundle of the stem is occupied. The bacteria have oozed to the inner surface of some 

 of the leaf-sheaths. 



One diseased badly: In the husks as well as in the stem. 



One badly diseased: Bacterial pockets in lower leaf-sheaths. The husks of the ear are diseased. 



One badly diseased: Here for the first time in my study of this disease I find evidence of bacterial ooze from the 

 pedicel of the cob (surface). It is water-soaked and yellow and there is ooze from a half-dozen or more stomata in the 

 form of short cirri. One of these cirrus threads is many times as long as broad. This material is so good that I will 

 put it into alcohol by itself (fig. 64 a). 



One badly diseased : Yellow bacterial ooze on inside of leaf-sheaths. 



Three badly diseased: In the largest one of the three there are water-soaked stripes on the internodes, and also a 

 badly diseased ear, the husks containing numerous yellow bacterial pockets from which slime has oozed to the inner face 

 of the husk. The lower leaf-sheaths are also crusted with yellow bacterial slime on the inner faces. 



One badly diseased : Every bundle of the stem occupied. 



Four badly diseased: Nearly every bundle occupied at the base of the stems. Also spots on the inner face of the 

 leaf-sheaths where the bacterial growth is bright yellow in patches, also many bacterial patches on the inner husks. 



One badly diseased: No ears. 



One badly diseased: Husks of the ear spotted with water-soaked and yellow places. 



One very badly diseased: Like most of these it has no living leaves. A badly infected ear. Many yellow spots 

 and much bacterial ooze on the inner husks. Nearly every bundle is occupied at tie base of the plant and I can count 

 at leasl a dozen bundles full of bright yellow slime at a distance of 6 feet from the ground and about 4 inches under the 

 male inflorescence. 



badlj diseased: Every bundle of the stem occupied. No ear. 



One badly diseased: Every bundle apparently is occupied at the base of the stem. Bacterial ooze from inside of 

 some of the leaf-sheaths and on the husks. 



One moderately diseased: Has perhaps 20 or 25 bundles occupied. 



