. Lectures on the evolution of plants. Botany; Plants. THE SIMPLEST FORMS OF LIFE 39 of the cell is occupied by colorless protoplasm, and near the outside is a bi-ight red pigment-mass — the "eye-spot" (e), near which can generally be detected one or two pulsating or contractile vacuoles} such as frequently oc- cur in the lower uni- cellular animals and in the slime-moulds. If these free-swim- ming green cells are placed in a glass vessel full of water, and placed where they are more strongly illuminated from one side, as for example in a window, it will be found that very soon they
. Lectures on the evolution of plants. Botany; Plants. THE SIMPLEST FORMS OF LIFE 39 of the cell is occupied by colorless protoplasm, and near the outside is a bi-ight red pigment-mass — the "eye-spot" (e), near which can generally be detected one or two pulsating or contractile vacuoles} such as frequently oc- cur in the lower uni- cellular animals and in the slime-moulds. If these free-swim- ming green cells are placed in a glass vessel full of water, and placed where they are more strongly illuminated from one side, as for example in a window, it will be found that very soon they collect on the lighted side, and, if they are present in large numbers, may be seen to form a green line close to the side where the light is strongest. [There is rea- son to suppose that the red eye-spot is in some way connected with this sensitiveness to light, as it is nearly always present in those motile green cells which show sensitiveness to light, and is. Fig. 6 (VolvocaceEo). — A, a plant of Pleodorina Oalifornica, showing the ciliated cells of whicli it is com- posed ; the arrow shows the direction in which it moves; B, one of the smaller cells, much enlarged, showing the two long cilia, c, the eye-spot, e, the nucleus, n, the pyrenoid, Pt im- hedded in the cup-shaped chloroplast, cl; C, three stages in the division of one of the large cells; D, the egg; E, spermatozoid of Volvox; F, two ga- metes of Pandorina fusing together to form the zygote, or resting-spore. (Figs. B, C, after Shaw; D, E, after Overton; F after Pringsheim.). 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 Campbell, Douglas Houghton, 1859-1953. New York, The Macmillan Co. , London, Macmillan & Co. , Ltd.
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Keywords: ., bookcentury1800, bookdecade, booksubjectbotany, booksubjectplants
