. The animans and man; an elementary textbook of zoology and human physiology. es consist of, let us consider as an example the lifeof a common bird. We know that after hatching from theegg it takes food, learns the notes of the parent bird, learnsto fly, learns to fight or to avoid enemies, all these includingmotions guided by sight, hearing, touch, and smell. Onthe approach of winter it migrates to the south; in springit returns, chooses a mate, builds a nest, and rears youngto which it teaches in turn the ways of bird life. Whilethe full explanation of these processes is far from beingreach
. The animans and man; an elementary textbook of zoology and human physiology. es consist of, let us consider as an example the lifeof a common bird. We know that after hatching from theegg it takes food, learns the notes of the parent bird, learnsto fly, learns to fight or to avoid enemies, all these includingmotions guided by sight, hearing, touch, and smell. Onthe approach of winter it migrates to the south; in springit returns, chooses a mate, builds a nest, and rears youngto which it teaches in turn the ways of bird life. Whilethe full explanation of these processes is far from beingreached, and while we cannot here discuss them at length, ANIMAL PHYSIOLOGY yet we may at least examine some of the parts of the bodyspecially concerned with these processes. In the higheranimals they are determined and directed by means of thesense-organs and the nervous system. In vertebrates thespecial senses, as they are called, are those of sight, hearing,smell, taste, touch, cold, heat, and one called the muscular Sunfish. Toad. Snake. Sparrow. Mouse. olf. md. br. -. sp. cd. \ FIG. 23. Diagram of brains of vertebrates; olf. /., olfactory lobes; cbr.,cerebrum; mi. b .. midbrain (optic lobes); cbl., cerebellum; rued,ob., medulla oblongata; sp. cd., spinal cord. sense. A part of the eye known as the retina is speciallysensitive to light; in the internal ear there are certain cellswhich are affected by sound vibrations; in the nasal passagesthere is a region in which are cells sensitive to odors; in theskin of the tongue are cells that react to sweet, sour, andbitter liquids; in various parts of the skin are cells sensitiveto pressure, heat, and cold. These different kinds of cellsaffected by different influences are called sense-cells. Now what the animal sees, hears, touches, etc., deter-mines its motions, and we find that the sense-cells are con-nected with the muscles by means of the nervous this connection light, heat, sound, etc., guidemuscular action.
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Keywords: ., bookcentury1900, bookd, booksubjectphysiology, booksubjectzoology
