. Bulletin. Natural history; Natural history. 420 Illinois Natural History Survey Bulletin Vol. 23, Art. 4. Fig. 19.—Cross section of xylem of elm affected with wetwood, showing tyloses in many vessels. Bacteria are occasionally present in some of the vessels. They are observed most frequently where tyloses are abundant. X130. a second 2-year-old seedling when the cut portion of the stem was submerged in sap from a diseased elm indicates that such sap prevents or at least retards the forma- tion of callus. Many of the ray and parenchyma cells near the surface of the trunk incision which was su
. Bulletin. Natural history; Natural history. 420 Illinois Natural History Survey Bulletin Vol. 23, Art. 4. Fig. 19.—Cross section of xylem of elm affected with wetwood, showing tyloses in many vessels. Bacteria are occasionally present in some of the vessels. They are observed most frequently where tyloses are abundant. X130. a second 2-year-old seedling when the cut portion of the stem was submerged in sap from a diseased elm indicates that such sap prevents or at least retards the forma- tion of callus. Many of the ray and parenchyma cells near the surface of the trunk incision which was submerged, in sap became filled with brown, gumlike material. The Wetwood Organism Five bacterial isolates, representative of the numerous isolates obtained from elms affected with wetwood, each obtained from a different elm, were studied for their morphology, cultural characters and biochemical reactions. Isolates 1, 3, 4 and 5 were obtained from wetwood-affected elms which had wilted. Isolate 2 was obtained from a wetwood-affected elm which had not wilted. Isolates 1, 2 and 4 were from parkway trees, while isolates 3 and 5 were from nursery trees. Morphology.—These five isolates are believed to represent a single species of bacterium. The organism is a short rod with rounded ends and occurs singly or, rarely, in pairs or chains, fig. 20. Cultures on potato dextrose agar (pH ) incubat- ed at 24 degrees C. for 48 hours produced cells measuring mostly ;.. This or- ganism is Gram-negative, motile, not acid- fast, and has up to six peritrichiate flagella measuring up to 11/a long, fig. 21. Cap- sules and spores were not observed. Cultural Characters.—Growth in nutrient broth appears in 24 hours or less and the broth becomes strongly clouded or turbid, with a decided kidney bean odor. The organism usually forms a thin pellicle or flocculent surface growth when undisturbed. Sediment is usually scant and viscid but becomes abundant if
Size: 1802px × 1387px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
