. The essentials of botany. Botany. 140 BOTANY. resting spore (e), which soon becomes coated with a thick wall (/). After a longer or shorter time the resting spore may germinate, which it does by bursting its wall and di- viding its contents into two parts, each of which finally becomes a new desmid {g, li, i). 246. The Diatoms {Diatomacece) are microscopic uni- cellular water-plants, resembling the desmids, but differ- ing from them in having walls which are silicified, and in the chlorophyll being hidden by the presence of a yellow coloring matter (phycoxanthin). Each cell is usti- ally com
. The essentials of botany. Botany. 140 BOTANY. resting spore (e), which soon becomes coated with a thick wall (/). After a longer or shorter time the resting spore may germinate, which it does by bursting its wall and di- viding its contents into two parts, each of which finally becomes a new desmid {g, li, i). 246. The Diatoms {Diatomacece) are microscopic uni- cellular water-plants, resembling the desmids, but differ- ing from them in having walls which are silicified, and in the chlorophyll being hidden by the presence of a yellow coloring matter (phycoxanthin). Each cell is usti- ally composed of two similar portions, called the valves* Each valve may be described as a disk whose edge is turned down all around, so as to stand at right angles to the remainder of the surface, making the valve have the general plan of a pill-box cover. The two vajves are generally slightly different in size, so that one slips within the other {A, Fig. 73), thus forming a box with double sides. In other cases the â ââ , ^ ^ . , valves are simply opposed Fig. 72.â^, front view of a dia- ^ â¢' ^^ torn, showing the overlapping walls; and do not overlap. B, same view of a diatom undergo- -^ ing fission; C, side or top view of a oA"? rT'T,â ;»,^iâ;,q,,âiâ «,ââ diatom (Navicula viridis), showing '*47. ihe individuals may markings. Highly magnified. â ± â -i â i â â exist Singly or m loose fami- lies; they are free, or attached to other objects by Httle stalks, and they are frequently imbedded in a mucous se- cretion. The free forms are locomotive, and may be seen in constant motion under the microscope: the mechanism of the motion is not certainly 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 Bessey, Charles E. (Charles Edwin), 1845-1915. New York : Holt
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1896
