. Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . e peculiar openings with which both sur-faces of most leaves are provided—the germ tube passesto the interior of the leaf through it, as shown at a,Fig, 6. If no breathing pore is in the immediate vicin-ity, the germinating spore bores through the cell wall,as shown at c. After the jiarasitic fungus has thus entered theinside of the leaf it develojos rapidly at the expense ofthe tissues of the latter. It j)ushes its threads, orJiypJice, about between the
. Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . e peculiar openings with which both sur-faces of most leaves are provided—the germ tube passesto the interior of the leaf through it, as shown at a,Fig, 6. If no breathing pore is in the immediate vicin-ity, the germinating spore bores through the cell wall,as shown at c. After the jiarasitic fungus has thus entered theinside of the leaf it develojos rapidly at the expense ofthe tissues of the latter. It j)ushes its threads, orJiypJice, about between the cells, choking up the cavitieswhich occur in the healthy leaf, and absorbins^ the con-tents of the cells. In many species of Peronospora the PARASITIC FUXGI 9 threads that run between the cells send into the cellsthemselves little processes called suckers, or haustoria,which assist in absorbing the cell contents. Thus, inthe downy mildew of the grape this occurs in a wayillustrated at Fig. 7. Tliese threads running throughthe leaf lead to the disorganization of its tissues, causingthe cells to collapse and turn brown. When they have. FIG, 6. SURFACE OF POTATO LEAF GREATLY MAGNIFIED, SHOWINGGERMINATING SPORE ENTERING BREATHING PORE AT a,AND GOING THROUGH EPIDERMIS AT C. developed to a considerable extent they collectively formthe mycelinm of the fungus. After the Peronospora plant has reached this stagein its existence it is ready to prepare for sends out through the breathing pores of the leafbranching threads, and on these develops the conidia, asalready described. By means of these conidia, which are produced ingreat abundance, and the swarm-spores originating from
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpathoge, bookyear1896
