. Outlines of the comparative physiology and morphology of animals. Anatomy, Comparative; Physiology, Comparative. MUSCULAR AND SKELETAL SYSTEMS. 239 character and the saucerlike (Fig. 154) or bell-shaped form and graceful movements of these beautiful crea- tures are well known. Their locomotive apparatus consists of fine muscular fibers, arranged in circular and radiating manner on the interior of the saucer or bell. When these fibers contract, the saucer or bell is drawn together, the water expelled, and the animal driven in the contrary direction. When the fibers relax, the somewhat firm, g
. Outlines of the comparative physiology and morphology of animals. Anatomy, Comparative; Physiology, Comparative. MUSCULAR AND SKELETAL SYSTEMS. 239 character and the saucerlike (Fig. 154) or bell-shaped form and graceful movements of these beautiful crea- tures are well known. Their locomotive apparatus consists of fine muscular fibers, arranged in circular and radiating manner on the interior of the saucer or bell. When these fibers contract, the saucer or bell is drawn together, the water expelled, and the animal driven in the contrary direction. When the fibers relax, the somewhat firm, gelatinous mass again expands by- its own elasticity to its original form and size. PROTOZOA. Infusoria.—In these, again, we have a wholly differ ent mode, viz., ciliary motion and locomotion. If the ani mal be fixed, as a, then the incessant lashing of micro scopic cilia, situated mainly about the mouth, creates whirling currents, which lead down to the throat, and thus contribute to alimentation. Whatever is suitable as food goes down ; what is not, is rejected and carried away by the same current. But if the body is free, 6, the same ciliary motion, react- ing against the water, produces the most vivacious loco- motion. Under the microscope it is seen to whirl and dart about in every direction without visible means; but with the higher power, especially when the motion is slower, the incessant lashing of the cilia is visible. Rhizopods.—Here we have motion, as well as all other functions, reduced to simplest terms, and find its origin in general contractility of protoplasm. The struc- tureless, or almost structureless, mass of living jelly con- 17. Fig. 155.—Infusoria: a, an at- tached form : d, a free 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 LeConte, Joseph, 1823-1901. New York, D. App
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