. Diseases of plants induced by cryptogamuc parasites; introduction to the study of pathogenic fungi, slime-fungi, bacteria, and algae. English ed. by William G. Smith. Plant diseases; Parasitic plants. EFFECT OF PARASITIC FUNGI ON THE FORM UF HOST-PLANT. 31 Somewhat doubtful cases are the outgrowths resembling aerial roots which arise on Laurus canariensis attacked by Ejxbasidium lauri. Geyler, their discoverer, regarded them as deformed stem- shoots, but they resemble rather the galls of the alpine-rose. § 6. EFFECT OF PARASITIC FUNGI ON CELL-CONTENTS. The most common and, at the same time,
. Diseases of plants induced by cryptogamuc parasites; introduction to the study of pathogenic fungi, slime-fungi, bacteria, and algae. English ed. by William G. Smith. Plant diseases; Parasitic plants. EFFECT OF PARASITIC FUNGI ON THE FORM UF HOST-PLANT. 31 Somewhat doubtful cases are the outgrowths resembling aerial roots which arise on Laurus canariensis attacked by Ejxbasidium lauri. Geyler, their discoverer, regarded them as deformed stem- shoots, but they resemble rather the galls of the alpine-rose. § 6. EFFECT OF PARASITIC FUNGI ON CELL-CONTENTS. The most common and, at the same time, most apparent effect of parasitic fungi in this direction, is the stimulation to cell-division and cell-multiplication. Tliis occurs chietly in young tissues, or in those still in process of growth, and gives rise to numerous peculiar outgrowths and swellings, some of which have already been referred to. The parenchyma of mature tissues may also exhibit secondary cell-division, when under the influence of a parasitic fungus. This I found to be the case in leaf- petioles of Umbelliferae attacked by Protomyccs viacrosjjorus (Fig. 9). The epidermis and vascular bundles are never disturbed, but the intervening tissues are permeated by an intercellular mycelium, which causes the cells to divide into a larue number of delicate-walled chambers, ^ „ , „ .. . '^ Fio. 0.—Secondary ccU-division all containing nuclei smaller than those in parenchyma of (.f/o- '~ jioUiuiii as a result of Protonti/ces of neiiihbourinff undivided cells. The macroAponts. The nudei of'the ~ ° _ new cells are much smaller than same thins is observed in plants of those of the primary ceii. (Cum- " _ _ ^ . pare Fig. 47.) (v. Tubeuf del.) Viola odorata inhabited by Uroci/stis violae; the mature parenchymatous cells become di\ided up by means of delicate walls running in various directions into numerous chambers or secondary cells, which Wakker in describing has named " nutritive tissu
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectparasit, bookyear1897
