. A handbook of cryptogamic botany. Cryptogams. Fig. 28S.—Simple sporophores of PhytophtJiora infestans de By. a, formation of fiist spores (zoosporanges) at ends of branches ; b^ two ripe spores on each branch and a third being formed {x about 200). (After de Bary.) Phytophthora, which resemble those of Peronospora in general habit, differ from them in the fact that each branch bears more than one pro- pagating body—not in chains, like Cystopus, but at intervals on the branch. In P. infestans a propagating cell is produced at the apex of each branch ; and as it ripens a papilla-like swelling
. A handbook of cryptogamic botany. Cryptogams. Fig. 28S.—Simple sporophores of PhytophtJiora infestans de By. a, formation of fiist spores (zoosporanges) at ends of branches ; b^ two ripe spores on each branch and a third being formed {x about 200). (After de Bary.) Phytophthora, which resemble those of Peronospora in general habit, differ from them in the fact that each branch bears more than one pro- pagating body—not in chains, like Cystopus, but at intervals on the branch. In P. infestans a propagating cell is produced at the apex of each branch ; and as it ripens a papilla-like swelling arises beneath it ; the branch grows on and turns the cell aside. These propagat- ing cells are usually zoosporanges, but not unfrequently they are coni- diospores, differing from them in no other respect than the pro- duction of a germ-tube directly instead of zoospores. The zoo- ).—Zoasfar3n%esoi Phytophthora infestans spores are formed mthin and de By. a, division completed: b^ escape of zoo- ,. , ^ spores ; c. free zoospores; d, spores come to rest CSCapC QireCtly irOm the ZOOSpO- and germinating (x 390). (After de Bary.) ^^^^^ j^^^j^^ ^^ ^^ PcrOnOSpOra. Phytophthora infestans has a special economic interest, as the cause of the well-known potato-disease. The disease first appears, as a rule, on the green leaves of the potato plant in July or August, the sporangio- phores emerging through the stomates. Sporanges are formed, under favourable conditions of temperature, moisture, &c., in a few hours, are. 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 Bennett, Alfred W. (Alfred William), 1833-1902; Murray, George Robert Milne, 1858-. London, New York, Longmans, Green, and Co.
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