. Elements of plant biology. Plant physiology. 72 PROTOPLASM AND THE AMCEBA. PROTOCOCCUS divides into two. The nucleus first divides into two equal parts, and then a furrow appears in the cytoplasm and rapidly deepens till the two halves become entirely separate. This simple method of multiplication is called binary fission. Each of the halves is a complete amoeba in every respect, and each proceeds to lead its own independent life and ultimately grows to the size of the parent amoeba, when it divides again in the same way. [The amoeba has other modes of reproduction which will not be dealt wi
. Elements of plant biology. Plant physiology. 72 PROTOPLASM AND THE AMCEBA. PROTOCOCCUS divides into two. The nucleus first divides into two equal parts, and then a furrow appears in the cytoplasm and rapidly deepens till the two halves become entirely separate. This simple method of multiplication is called binary fission. Each of the halves is a complete amoeba in every respect, and each proceeds to lead its own independent life and ultimately grows to the size of the parent amoeba, when it divides again in the same way. [The amoeba has other modes of reproduction which will not be dealt with here.] Protococcus.—On the bark of trees, on old Fig, 4.—Cells of Protococcus viridis. x about,8oo. Each is bounded by a colourless cell waU (cm.). The shaded portion is the green chloroplast which frequently occupies most of the space within the wall (6 and c); pyr., pyrenoid. In a and d the cells have recently divided and are remaining together. etc., especially on the north side, which does not en- counter the direct rays of the sun and thus tends to remain damp, one often finds the surface covered with a thin green crust, which crumbles in dry weather under the point of a knife. If a little of this green crust is scraped off into a drop of water on a slide and examined first with the low and then with the high power, it is seen to consist of numerous very small green cells, which often hang together in groups of two, four, or more. This is a minute unicellular alga. 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 Tansley, Arthur George, 1871-. London, George Allen & Unwin Ltd. ; New York, Dodd, Mead & Co
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectplantph, bookyear1922
