. Adventures with animals and plants. Biology. B Fig. 361 Five stages in the reproductioii of an ameba. How does B differ frotn A? What changes are shown in C? What is happening in D? ing in its pseudopods; it becomes less active. The nucleus comes to rest near the center of the cell and divides. While the nucleus is dividing, the cytoplasm streams in opposite directions away from the center of the cell. The two new nuclei move away from one another along with the cytoplasm. The two re- sulting parts then seem to pull away from each other. The cytoplasm con- necting them becomes thinner and th
. Adventures with animals and plants. Biology. B Fig. 361 Five stages in the reproductioii of an ameba. How does B differ frotn A? What changes are shown in C? What is happening in D? ing in its pseudopods; it becomes less active. The nucleus comes to rest near the center of the cell and divides. While the nucleus is dividing, the cytoplasm streams in opposite directions away from the center of the cell. The two new nuclei move away from one another along with the cytoplasm. The two re- sulting parts then seem to pull away from each other. The cytoplasm con- necting them becomes thinner and thin- ner until finally it is only a thread, which breaks. In about half an hour one ameba becomes two amebae, each with its own nucleus. The new amebae rapidly gro"w to full size. This division of the nucleus and the separating of the cell body into two equal parts in a one-celled organism is a process known as binary fission (by'na- ree fish'un). In binary fission, as you just read, the parent disappears; the whole organism makes the two offspring. These two are often spoken of as the daughter cells and the parent as the mother cell. Strictly speaking, there are neither daughters nor mothers; but no better names have been found. Binary fission occurs not only in ame- bae and Paramecia but in other protozoa and in many single-celled plants. Note that cell division in a many-celled organ- ism is not called binary fission because new organisms do not result. The term binary fission is reserved for the repro- duction of a single-celled animal or plant. A variation from binary fission. An equally simple but far less common method of reproduction takes place in the yeast plant, many thousands of which make up a cake of yeast. In re- production, the nucleus moves to one Bud forming. 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
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Keywords: ., bookcentury1900, bookpublisherbostondcheath, booksubjectbiology
