. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. THALLOPHYTA. 671 in the oogonia (fig. 382), and these germinate parthenogenetically. Although the sexual organs are still preserved in this group their function has been lost, leading the way to their complete atrophy in many other groups of Fungi. Many members of the group occur upon the bodies of dead insects and fish { various species of Saprolegnia, Achlya, Aphanomyces). Aphanomyces phycophilus is parasitic upon Algse ( Spirogyra) and Saprolegnia Ferax upon Salmon, &c. About 45 specie
. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. THALLOPHYTA. 671 in the oogonia (fig. 382), and these germinate parthenogenetically. Although the sexual organs are still preserved in this group their function has been lost, leading the way to their complete atrophy in many other groups of Fungi. Many members of the group occur upon the bodies of dead insects and fish { various species of Saprolegnia, Achlya, Aphanomyces). Aphanomyces phycophilus is parasitic upon Algse ( Spirogyra) and Saprolegnia Ferax upon Salmon, &c. About 45 species have been distinguished. GhytridiacecB.—Small parasitic aquatic Fungi whose mycelium is almost entirely wanting; they produce characteristic spor- angia which liberate uniciliate swarm-spores. Polyphagus EuglericE develops a very delicate mycelium, of which the branches become attached to Euglena-cells (fig. 379^, two Euglenas are thus attacked), and from the central portion of the mycelium arises a sporangium from which uniciliate swarm- spores (fig. 379*) are liberated. These in turn germinate, develop threads, and entangle fresh Euglenas. Rhiziddomyces attacks the oogonia of Saprolegnias, sending a branching mycelium into their interior (fig. 379®) and producing a pear-shaped sporangium at the surface which liberates numerous swarm- spores. Ghytridium Olla (fig. 380*) pro- duces its sporangia on the oogonia of (Edo- gonvwm; its swarm-spores escape by the removal of a lid. Over 180 species are known. AncylistacecB.—Very nearly resemble the Chytridiacese in mode of life, but difier in exhibiting sexuality. Lagenidm/m Rahen- horstii attacks cells of Spirogyra, &c. The spores become attached to the Spiro- gyra-cells, and penetrate the wall (fig. 379^) by means of a tube which branches about within, forming a lobed, irregular body (fig. 379 ^), which may open at the outside, liberating swarm-spores (fig. 379^), or sexual organs may arise inside and fertilization take p
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
