. Principles of economic zoo?logy. Zoology, Economic. "INSECTA 121 of kidneys. There is no liver. The entire viscera are en- veloped in the " iat ; The anal opening is in the last segment of the abdomen. Insects feed upon the juices, leaves, or even the wood of plants, or are parasitic or predaceous upon various forms of insects, and upon other animals as well. Some live upon de- caying organic Fig. 94.—Ideal transverse section of an insect: h, Dorsal vessel; i, intestine; n, ventral nerve-cord; t,t, stigmata leading into the branched tracheal tubes; w, w, wings; a
. Principles of economic zoo?logy. Zoology, Economic. "INSECTA 121 of kidneys. There is no liver. The entire viscera are en- veloped in the " iat ; The anal opening is in the last segment of the abdomen. Insects feed upon the juices, leaves, or even the wood of plants, or are parasitic or predaceous upon various forms of insects, and upon other animals as well. Some live upon de- caying organic Fig. 94.—Ideal transverse section of an insect: h, Dorsal vessel; i, intestine; n, ventral nerve-cord; t,t, stigmata leading into the branched tracheal tubes; w, w, wings; a, coxa of one leg; b, trochanter; c, femur; d, tibia; e, tarsus. (After Packard.) The circulatory organs are extremely primitive in character. The heart or dorsal vessel extends through the abdomen just underneath the dorsal surface. It is partially divided bj^ valves into chambers, the number of which varies. The anterior chamber extends into or near the head and is sometimes called the aorta; The heart chambers pulsate rhythmically, from the posterior one forward, and force the blood out into the body cavity. There are no veins or arteries, so it flows through the sinuses or open spaces between the organs, bathing the tissues, and finally bathing the walls of the alimentary tube, where it. 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 Daugherty, Lewis Sylvester, 1857-; Daugherty, L. S. , Mrs. , 1859-. Philadelphia, London, W. B. Saunders
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