. Nature and development of plants. Botany. 196 SEXUAL REPRODUCTION OF VAUCHERIA injury to the filaments. Asexual reproduction is effected by very large zoospores which are developed in the enlarged extremities of the filaments (Fig. 113,5). These tips are cut off by a transverse wall and a single zoospore escapes through an opening in the tip of the sporangium thus formed. The entire surface of the zoospore is clothed with cilia arranged in pairs, each pair being associated with a nucleus so that the zoospore resembles the motile colonies previously noted (Fig. 113, C). After a very short mot
. Nature and development of plants. Botany. 196 SEXUAL REPRODUCTION OF VAUCHERIA injury to the filaments. Asexual reproduction is effected by very large zoospores which are developed in the enlarged extremities of the filaments (Fig. 113,5). These tips are cut off by a transverse wall and a single zoospore escapes through an opening in the tip of the sporangium thus formed. The entire surface of the zoospore is clothed with cilia arranged in pairs, each pair being associated with a nucleus so that the zoospore resembles the motile colonies previously noted (Fig. 113, C). After a very short motile period, the zoospore comes to rest and grows into the characteristic tubular plant (Fig. 113, D). When the plants are exposed to too dry conditions, the tips of the filaments often. Fig. 114. Sexual reproduction of Vaucheria: A, portion of a filament that has formed two branches which have grown into a male, an, and female, og, gametangia. B, later stage, the gametangia have opened, permitting the escape of the male gametes and the fertilization of female gamete. C, gam- etospore detached from the filament. enlarge and finally become detached as motionless spores that germinate when conditions are again favorable. The male and female gametes are produced in gametangia that are formed from short branches. The males are developed in large numbers in curved branches that become cut off from the filament by a cross wall (Fig. 114, A) and the gametes finally escape through an opening that forms at the apex of the branch. A gametangium that produces clearly differentiated male gametes is called an antheridium (plu. antheridia) and the gametes are frequently called antherozoids or sperms. A single female. 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 Curtis, Carlton Clarence, 1864-1945. New York, H. Holt
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