Identifier: naturalhistoryof02kern (find matches)
Title: The natural history of plants, their forms, growth, reproduction, and distribution;
Year: 1902 (1900s)
Authors: Kerner von Marilaun, Anton, 1831-1898 Oliver, Francis Wall, 1864- Macdonald, Mary Frances Ewart Busk, Marian Balfour, Lady
Subjects: Botany
Publisher: London, Blackie
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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ce,Entomophihorece. Mycelium often very slightly developed; asexual reproduction by means ofswarm-spores; sexual reproduction by egg-cells. On the whole in this group we aredealing with Fungi which very nearly resemble the Algoe of the Alliance SiphoneaB(e.g. Vaucheria) both as regards the structure of their mycelium and mode of repro-duction. A loss of sexuality is to be noted in many members of this group. THALLOPHYTA. 669 Peronosporece.—Are mostly parasitic upon Flowering Plants, and the cause ofmany destructive diseases. They establish themselves by means of a branching,tubular, non-septate mycelium which penetrates the intercellular system of the host-plant (cf. p. 56). They propagate asexually by means of unicellular sporangia bonieon branched hyphse which project from the stomates, &c., of the host (cf. fig. 3812);these sporangia (or spores as they are sometimes termed) liberate on a moist sub-stratum a number of swarm-spores (figs. 381 ^-^^ 6) which originate new plants.
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Swarm-spores in Saprolegniacese and ChytriJiacea;. Achlya prolifera. 2, s, i Successive stages of swarm-spore-formation in Achlya proli/era. Chytridiinn Olla, parasitic 011 theoogonium of the Alga (Edogonium; development of swarm-spores. ^Saprolegnia lactea. Development of swarni-sporesin the same. (Partly after De Bary and Pringslieim.) 1 x 20; 2, a, < x 400; « x 300; « x 100; x 300. Sexual reproduction also takes place by the formation of oogonia and tube-likeantheridia. The latter become attached to the former (fig. 381^), and, putting outfertilizing tubes which penetrate to the egg-cell within the oogonium, transmit theirspermatoplasm. No spermatozoids are differentiated, but the spermatoplasm travelsen masse. The fertilized egg-cell enters on a resting stage, and when it germinatesmay either give rise to swarm-spores (e.g. Cystopus) or grow at once into a newplant (Pythium, Peronospora). To Phytophthora infestans is due the well-known Potato-disease. The Fungus attacks the f

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