90
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THE _BIOLOGY OF FISHES
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back; Wccanùnderstand this phenomenon on comparing
With the rocking movements of a vessel. _When the
_
centre
of gravity is well- below that of_buoyanoy,,thé;pper
{—-_— part has a short but rapid-swing and the dorsà1:zÿàyië h_aV_e
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diioul‘tyin developing ; where the centïepf gravitÿis àbove_
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FIG 21—Changeofformw1thcentreofgraVl‘ûÿ
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Ametronomenughtalso
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heei;—‘£çglÿ!jiiñportant ii_p}»th€il differentiation.'
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