Principles of Zoology: Touching the Structure, Development, Distribution ...
Principles of Zoology: Touching the Structure, Development, Distribution ...
Louis Agassiz
The book Principles of Zoology: Touching the Structure, Development, Distribution ... was written by author Louis Agassiz Here you can read free online of Principles of Zoology: Touching the Structure, Development, Distribution ... book, rate and share your impressions in comments. If you don't know what to write, just answer the question: Why is Principles of Zoology: Touching the Structure, Development, Distribution ... a good or bad book?
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equally concerned in effecting locomotion, or only some ot its parts are employed for the purpose. 165. The jelly-fishes (Medussa) swim by contracting their umbrella -shaped bodies upon the water below, and its resistance urges them forwards. Other animals are provided with a sac or siphon, which they may .fill with water and suddenly force out, producing a jet, which is resisted by the surrounding ^^' water, and the animal is thus propelled. The Biche-le-mar, (Holothuria,) the cuttle-fishes, t...he Salpse, &c., move in this way. 166. Others contract small portions of the body in suc- cession, which being thereby rendered firmer, serve as points of resistance, against which the animal may strive, in urging the body onwards. The earth-worm, -whose boJy is composed of a series of rings united by muscles, and shutting more or less into each other, has only to close up the rines at one or more points, to form a sort of fulcrum, against which the rest of the body exerts itself in extending forwards.
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