. The essentials of botany. Botany. PHYGOPHYTA. 153 fected. After fertilization eacli gorm-cell becomes covered with a wall of cellulose and is thus transformed into a rest- ing spore. 271. What is given above may be taken to illustrate the general mode of reproduction in the family. It presents much variation in the different genera and species, and in some cases the sexual organs are functionless, the resting- spores forming without an actual fertilization. The mature resting-spores are double-walled, the outer (exospore) being thick, and the inner (endospore) thin. After a considerable peri
. The essentials of botany. Botany. PHYGOPHYTA. 153 fected. After fertilization eacli gorm-cell becomes covered with a wall of cellulose and is thus transformed into a rest- ing spore. 271. What is given above may be taken to illustrate the general mode of reproduction in the family. It presents much variation in the different genera and species, and in some cases the sexual organs are functionless, the resting- spores forming without an actual fertilization. The mature resting-spores are double-walled, the outer (exospore) being thick, and the inner (endospore) thin. After a considerable period of repose the resting-spores germinate by sending out a tube, as in Green Felt. 272. The Downy Mildews and White Rusts {Perono- sporacem) live parasitically in the in- terior of higher plants. They are composed of long branching tubes, whose cavities are continuous throughout. They grow between the cells of their hosts, and draw nourishment from them by means of little branches {haustoria), which thrust themselves through the walls (Pig. 80). 273. The asexual spores (conidia) are produced upon branches (conidi- ophores) which protrude through the epidermis of the host. In the _ _,,.- ^ . „ ^ Fig. 80.—Showing one of iJowny Mildews (species OI PeronO- thehyph^ (m, m)of a Mil- ^ dew, sending suckers (haus- spora, Phytophthora, Plasmopara, ^^3'''*)^^^° *Ma° nmet ^^300 etc.) these branches find their way tidies. through the breathing-pores, and bear their spores singly upon lateral branchlets (Fig. 81); in the White Rusts. 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 Bessey, Charles E. (Charles Edwin), 1845-1915. New York : Holt
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1896
