. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. 158 COMPARATIVE ZOOLOGY. for locomotion. These become reduced in number, and progressively perfected, as we advance in the scale of rank. Thus, the Infusorian is covered with thousands of hair-like cilia; the Star-fish has hundreds of soft, unjoint- ed, tubular suckers; the Centipede has from 30 to 40 jointed hollow legs; the Lobster, 10; the Spider, 8; and the Insect, 6 ; the Quadruped has 4 solid limbs for loco- motion ; and Man, only 2. (1) Locomotion i
. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. 158 COMPARATIVE ZOOLOGY. for locomotion. These become reduced in number, and progressively perfected, as we advance in the scale of rank. Thus, the Infusorian is covered with thousands of hair-like cilia; the Star-fish has hundreds of soft, unjoint- ed, tubular suckers; the Centipede has from 30 to 40 jointed hollow legs; the Lobster, 10; the Spider, 8; and the Insect, 6 ; the Quadruped has 4 solid limbs for loco- motion ; and Man, only 2. (1) Locomotion in Water.—As only the lower forms of life are aquatic, and as the weight of the body is partly sustained by the element, we must expect to find the or- gans of progression simple and feeble. The Infusoria swim with great rapidity by the incessant vibrations of ' the delicate filaments, or cilia, on their bodies. The com- mon Squid on our coast admits water into the interior of the body, and then suddenly forces it out through a fun- nel, and thus moves backward, or forward, or around, ac- cording as the funnel is turned—towards the head, or tail, or to one side. The Lobster has a fin at the end of its tail, and propels itself backward by a quick down-stroke of the abdomen. But Fishes, whose bodies offer the least resistance to progression through water, are the most perfect swimmers. Thus, the Salmon can go twenty miles an hour, and even. Fig. 123—The Fins of a Fish (Pike-perch). ascend cataracts. They have fins of two kinds: those set obliquely to the body, and in pairs; and those which are. 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 Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950. New York : Harper & Bros.
Size: 2571px × 972px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1883
