. The elements of botany embracing organography, histology, vegetable physiology, systematic botany and economic botany ... together with a complete glossary of botanical terms. Botany. 128 SYSTEMATIC generally more or less con- stricted in the middle, and divided into two symmetri- cal half-cells. A sexual re- production takes place by the elongation and fission of the neck, uniting the two halves of the cells. The two small half-cells grow until 239 240 they are as large as the original ones, when they separate. Sexual reproduction results in the formation of a zygospore; thus, elon
. The elements of botany embracing organography, histology, vegetable physiology, systematic botany and economic botany ... together with a complete glossary of botanical terms. Botany. 128 SYSTEMATIC generally more or less con- stricted in the middle, and divided into two symmetri- cal half-cells. A sexual re- production takes place by the elongation and fission of the neck, uniting the two halves of the cells. The two small half-cells grow until 239 240 they are as large as the original ones, when they separate. Sexual reproduction results in the formation of a zygospore; thus, elongations, or conjugating tubes, of two adjacent cells grow out till they meet, their protoplasm fuses upon the absorption of the partition between them, and this becomes covered with a thick wall, or exospore. 162. The Diatoms (JDiatomaeem), as are also the Desmids, are microscopic, unicellular Algse (Fig. 241), with a multi- tude of ornamental forms. They differ, however, in having silicious cells, and their chlorophyll concealed by a brown- ish or yellowish coloring matter, called phycoxanthine. The cell (called a frustule) consists of two portions, called valves, one of which is slightly larger and fits over the other like the lid of a pill-box. Ee- production takes place very similar to that in the Desmids, the protoplasm divides in a plane parallel to the valves, each portion secretes a shell or valve, which, in every case, is slightly smaller and fits into the old or outer valve. It is evident, therefore, that as multiplication by fission con- Fig. 239. Micrasterias/areata, a Desmld. Fig. 240. Cosmaritim parimla, i. Desmid. Fig. 241. Navicula vtridU, a 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 Kellerman, William Ashbrook, 1850-1908. Philadelphia, J. E. Potter and Company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1883
