. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. XIII. METAZOA Division of Labor. — If we compare the amoeba and the para- moecium, we find the latter a more complex organism than the former. An amoeba may take in food through any part of the body; the paramoecium has a definite gullet; the amoeba may use any part of the body for locomotion; the paramoecium has definite parts of the cell, the cilia, fitted for this work. Since the structure of the paramoecium is more complex, we say that it is a " higher " animal. As we look hig
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. XIII. METAZOA Division of Labor. — If we compare the amoeba and the para- moecium, we find the latter a more complex organism than the former. An amoeba may take in food through any part of the body; the paramoecium has a definite gullet; the amoeba may use any part of the body for locomotion; the paramoecium has definite parts of the cell, the cilia, fitted for this work. Since the structure of the paramoecium is more complex, we say that it is a " higher " animal. As we look higher in the scale of life, we invariably find that certain parts of a plant or animal are set apart to do certain work and only that work. This has resulted in what is called division of labor. Just as in a community of people, there are some men who do rough manual work, others who are skilled workmen, some who are shopkeepers, and still others who are professional men, so among plants and animals, wherever collections of cells live together to form an organism, there is division of labor. One of the simplest of all colo- nies is a collection of cells called Pandorina. This is a colony of sixteen cells, whether plant or ani- mal is uncertain, which have be- come joined by living together in a mass of jellylike material secreted by the cells. They move by means of cilia, and, as a result of living together, move faster through the water and thus obtain more food than one alone. Another form where division of labor is begun is seen in the plant (or animal) called Volvox. This is a hollow sphere of cells, the greater number 187. Colony of volvox: R, reproductive cells; C, ciliated cells. (After Kny.). 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 Hunter, George William, 1873-1948. New York, American book co
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