. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. IOO FUNGOUS DISEASES OF PLANTS Morphology. Fungus and deformity. The parasite is sup- posed to gain entrance to the host plant during the swarmspore stage, or immediately upon leaving the swarmspore stage, there- fore in the amceboidal form. No observations, however, have been made relative to host penetration, and the subject would doubtless prove an interest- ing one. A microscopic study of sections of the diseased root shows that the organism is most abundant in parenchymatous c
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. IOO FUNGOUS DISEASES OF PLANTS Morphology. Fungus and deformity. The parasite is sup- posed to gain entrance to the host plant during the swarmspore stage, or immediately upon leaving the swarmspore stage, there- fore in the amceboidal form. No observations, however, have been made relative to host penetration, and the subject would doubtless prove an interest- ing one. A microscopic study of sections of the diseased root shows that the organism is most abundant in parenchymatous cells, often in the vicinity of the cambium. There is in quantity an abnormal develop- ment of phloem. The xylem portions of affected roots are relatively inconspicuous. According to some observers, certain bundle elements may also show the parasite. The infested cells are ordinarily in groups (Fig. 20) and Nawaschin believes that these groups originate by the division of a single cell and that such groups may also transmit an in- fluence to similar tissues even at a distance, so that there may eventually result, for instance, histological disturbances in neigh- boring bundles. It is possible, however, that the young cells of the bundles may become infected and that the organism may be enabled to maintain itself in such cells for a time after differentia- tion of the latter as distinctive bundle elements. In an earlier stage the contents of the infected cells is of a half- fluid consistency, later turbid, and finally granular. Even in the first stage the parasite is noticeable in the amceboidal form and. Fig. 21. Stages in the Differentiation of the Plasmodium and Spores in Plasmodiophora Brassicjs. (After Nawaschin). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Duggar, Benjamin M. (Benjamin Minge), 1872-1
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Keywords: ., bookauthorduggarbe, bookcentury1900, bookdecade1900, bookyear1909
