| The Columbia Encyclopedia, Sixth Edition. 2001-07. |
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| book lung |
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| terrestrial respiratory organ characteristic of arachnids such as scorpions and primitive spiders. Each book lung consists of hollow flat plates. Air bathes the outer surface of the plates and blood circulates within them, facilitating the exchange of gases. In most species, adequate gas exchange occurs without any muscular movement to ventilate the lung. |
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| | | The Columbia Encyclopedia, Sixth Edition. Copyright © 2007 Columbia University Press. |
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