. Botany for agricultural students. Plants. 330 THALLOPHYTES plant and animal kingdoms. The protoplast is naked or in- vested by a membrane which usually contains no cellulose. They are commonly abundant in stagnant water and among Green Algae some are usually present. Euglena represented in Figure 284 is one of the most common of the 300 or more species and will serve to show the structure and habits of the group. Euglena is quite commonly seen swimming about under the microscope when Algae are be- ing examined. The slender unicellular body bears a long terminal flagellum, has a chlo- roplast
. Botany for agricultural students. Plants. 330 THALLOPHYTES plant and animal kingdoms. The protoplast is naked or in- vested by a membrane which usually contains no cellulose. They are commonly abundant in stagnant water and among Green Algae some are usually present. Euglena represented in Figure 284 is one of the most common of the 300 or more species and will serve to show the structure and habits of the group. Euglena is quite commonly seen swimming about under the microscope when Algae are be- ing examined. The slender unicellular body bears a long terminal flagellum, has a chlo- roplast, eye-spot, and pulsating vacuole. These structures are characteristic of the Algae, such as Volvocales and also of protozoa, the one-celled ani- mals. No sexuality is known, and multiplication is effected by longitudinal fission, a method characteristic of the lower animals. At the ap- proach of unfavorable condi- tions, as in autumn, it trans- forms itself into a thick-walled resting spore which germinates and produces one or more new plants when favorable condi- tions return. Although it usually makes its own food, sometimes Euglena loses its chlorophyll and lives on organic solutions as a saprophyte, thus demonstrating that the saprophytic may readily originate from the independent habit. Many of the Flagellates change their forms readily hke the Amoeba. Sometimes the individuals form colonies of various shapes and often variously branched. Such features as the possession of chlorophyll and the forma- tion of thick-walled resting spores suggest a relationship of the Flagellates to plants, while their swimming habits, amoeboid. Fig. 284. — A common species of Euglena {Euglena gracilis). At the left, an adult individual, showing the flagellum, the pulsating vacuole (p), the chloroplast (c), and the nucleus («) (X 650); at the right and below, Euglena in the spore stage (X 1000); at the right and above, a spore germi- nating and producing four new indi- viduals (X 1000). Re
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1919
