. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. LEAVES AND THEIR FUNCTIONS 139 from the axils of the true, very tiny, scalelike leaves. The spines noted in the cactus are examples of reduced leaves. Leaves as Insect Traps. — Most curious of all are the modifications of the leaf into insect traps. It frequently happens that the habitat of a plant will not furnish the raw food materials necessary to form proteid food and to build protoplasm. Nitrogen is the lacking element. The plant has become adapted to these conditions and obtains nitro
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. LEAVES AND THEIR FUNCTIONS 139 from the axils of the true, very tiny, scalelike leaves. The spines noted in the cactus are examples of reduced leaves. Leaves as Insect Traps. — Most curious of all are the modifications of the leaf into insect traps. It frequently happens that the habitat of a plant will not furnish the raw food materials necessary to form proteid food and to build protoplasm. Nitrogen is the lacking element. The plant has become adapted to these conditions and obtains nitrogenous food from the bodies of insects which it catches. Examples of insect traps are the common bladder- wort (Utricularia), the Venus's flytrap (Dioncea muscipula), the sundew (Drosera rotundifolia), and certain of the pitcher Bladderwort, showing finely dissected submerged leaves bearing blades which capture animalcula. Bladderwort.—The simplest contrivance for the taking of animal food by the leaf is seen in the bladderwort. Here certain of the leaves are modi- fied into little bladders provided with trapdoors w^hich open inwards. Small water-swimming crustaceans (as water fleas, etc.) push their way into the trap and there die, perhaps of starvation. Bacteria, causing decay, soon break down their bodies into soluble substances, the nitrogenous portion of which is absorbed by the inner surface of the bladders and used by the plant as food. Venus's Flytrap. — In the Venus's Kytrap, a curious plant found in our Southern states, the apex of the leaf is peculiarly modified to form an insect. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hunter, George William, 1873-1948. New York, American book company
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