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A Balanced Aquarium. The fish and other animals give off carbon dioxide and nitrogenous wastes which, under cer

tain conditions, are used by the green plants for the manufacture of food and living matter. The plants give off oxygen as a by-product during starch-making, and their bodies may be used as food by the animals.

PRESENTED IN PROBLEMS

BY

GEORGE WILLIAM HUNTER, A.M.

HEAD OF THE DEPARTMENT OF BIOLOGY, DE WITT CLINTON HIGH
SCHOOL, NEW YORK

AC

NEW YORK .:. CINCINNATI :· CHICAGO

AMERICAN BOOK COMPANY

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