Word: dup
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Dates: during 1920-1929
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...activity is effected by chemical reaction; that the efficiency of our muscles is 25 per cent something better that that of a steam engine; that a frog's muscle can lift one thousand times its won weight? Have you a clear conception of what causes the "lubb" and the "dup" of the heart beat? All these question open up a new field to the casual reader, along...