. Zoölogy [microform] : descriptive and practical. Zoology; Zoologie. Platyhelminthes. 049 mesoderm, and endoderm. Many of them are parasites, and some wholly lack a digestive tube. When present the digestive tube has but one opening, the mouth. They show a tendency to reproduction by self-division, and most of them when cut in two develop two individuals. The Tapeworm. — Probably the most widely known of the flatworms are the tapeworms. These are parasites in the digestive tube of various verte- brates, including man. As the name indicates, the body is ribbon-shaped, sometimes attaining a len
. Zoölogy [microform] : descriptive and practical. Zoology; Zoologie. Platyhelminthes. 049 mesoderm, and endoderm. Many of them are parasites, and some wholly lack a digestive tube. When present the digestive tube has but one opening, the mouth. They show a tendency to reproduction by self-division, and most of them when cut in two develop two individuals. The Tapeworm. — Probably the most widely known of the flatworms are the tapeworms. These are parasites in the digestive tube of various verte- brates, including man. As the name indicates, the body is ribbon-shaped, sometimes attaining a length of thirty feet. The body consists of segments, or proglottids, a tapeworm ten feet long having about eight hundred segments. There is no mouth nor digestive tube; none is needed, as the worm lives surrounded by material digested by another animal, and the parasite simply absorbs nourishment through its skin. There is a distinct head, whose chief work is that of at- taching the worm to the lining of the intestine; this is secured by a circle of hooks at the end of the head and four sucking disks on the sides. For a short distance from the head the body is unsegmented; then segments are formed by constrictions at intervals; farther on, the segments grow larger. Deve'opment of the Tapeworm. — The hinder segments of the tapeworm contain embryos. These segments drop off and the embryos are set free, passing out with the excrement. They are eaten by another animal the hog, for instance; in the intestine the embryo bores through the. Fig. 196. Tapeworm {Ttenia solium). In upper left hand corner of figure the head much mag- nified. After Leuckart. - From Jordan and Kel- logg's Animal 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 Colton, Buel P. (Buel Preston), 1852-1906. Toronto : Copp, Clark
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