. The animans and man; an elementary textbook of zoology and human physiology. 53. A simple sponge, Grantia sp.;at right a longitudinal section, showingthe simple body-cavity. (One-half natu-ral size; after Jordan and Kellogg.) 134 THE ANIMALS AND MAN a meter (39 in.) in height. In color they may be red, purple, orange, gray, and sometimes blue. Examine a bath sponge and note the holes in it. These are to let in and out the sea-water, in which float the minutebits of animal or plant sub-stance on which the spongefeeds. This water also bringsoxygen for the breathing ofthe sponge, and carries aw
. The animans and man; an elementary textbook of zoology and human physiology. 53. A simple sponge, Grantia sp.;at right a longitudinal section, showingthe simple body-cavity. (One-half natu-ral size; after Jordan and Kellogg.) 134 THE ANIMALS AND MAN a meter (39 in.) in height. In color they may be red, purple, orange, gray, and sometimes blue. Examine a bath sponge and note the holes in it. These are to let in and out the sea-water, in which float the minutebits of animal or plant sub-stance on which the spongefeeds. This water also bringsoxygen for the breathing ofthe sponge, and carries awaythe carbon dioxide given offby it. But the sponge has nospecial organs, its soft fleshbeing able to digest food andtake up oxygen without stom-ach or lungs. The living sponges are col-lected by divers, or are draggedup by men in boats with long-poled hooks or dredges. They are first killed byexposure to the air, and thenthrown into tanks of the flesh decays away,leaving the tough, horny, orleathery skeleton, which, whencleaned, bleached, and trim- FIG. 54. The
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