. Elements of botany. Botany; Botany. 224 ELEMENTS OF" BOTANY. conjugation by leaving the Spirogyra filaments in very cold water over night, and in this way the successive steps of the conjugating process may be studied by daylight. In such ways the series of phenomena shown in Fig. 195 has been clearly made out. If the student cannot follow these operations under the mi- croscope, he may at least by looking over the yellower portions of a mass of Spirogyra find threads containing fully formed zygospores, like those shown in B, Fig. 195. A' Fig. 195. — Formation of Spores by Conjugat
. Elements of botany. Botany; Botany. 224 ELEMENTS OF" BOTANY. conjugation by leaving the Spirogyra filaments in very cold water over night, and in this way the successive steps of the conjugating process may be studied by daylight. In such ways the series of phenomena shown in Fig. 195 has been clearly made out. If the student cannot follow these operations under the mi- croscope, he may at least by looking over the yellower portions of a mass of Spirogyra find threads containing fully formed zygospores, like those shown in B, Fig. 195. A' Fig. 195. — Formation of Spores by Conjugation in Spirogyra. A, two filaments of Spirogyra side by side, with tbe contents of adjacent cells uniting to form spores z. At the bottom of the figure the pro- cess is shown as beginning, at the top as completed, and the cells of one filament emptied ; B, a single filament of another kind of Spiro- gyra, containing two spores, one lettered?;. (^magnified240diame- ters, J3 150 diameters.) 274. Characteristics of Algce. — The Protococcus and the Spi- rogyra are two common fresh- vsrater examples of the kind of plants classed under the general name of AlgcB, a group of which the largest and most interesting examples are to be found among the seaweeds. Algae are all aquatic, or at least live usually in damp places; they contain chlorophyll, and are therefore capable of absorbing carbonic acid gas and fixing carbon; few algse are parasitic or saprophytic. In fact, the main distinction be- tween this group and the fungi lies in the self-supporting char- acter of the former plants and the parasitic or saprophytic (§ 151) character of the latter. For this reason the two groups, based on the characteristic behavior or mode of life of their members, rather than on the real relationships of the. 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 perfectl
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