. Elements of comparative zoology. Zoology. 216 SYSTEMATIC ZOOLOGY. only be ascertained by the appendages or by the features presented in development. Usually these segments can be grouped in regions, of which, at most, three can be distinguished: in front the head; next^ the thorax; and behind, -the abdomen (fig. 48). The head is largely concerned in the taking of food,. Pig. 48s—Diagram of grasshopper showing the body divided into the three regions: head, thorax, and abdomen. and is usually the seat of the special senses. The thorax is the locomotor region, while in the abdomen the primi- ti
. Elements of comparative zoology. Zoology. 216 SYSTEMATIC ZOOLOGY. only be ascertained by the appendages or by the features presented in development. Usually these segments can be grouped in regions, of which, at most, three can be distinguished: in front the head; next^ the thorax; and behind, -the abdomen (fig. 48). The head is largely concerned in the taking of food,. Pig. 48s—Diagram of grasshopper showing the body divided into the three regions: head, thorax, and abdomen. and is usually the seat of the special senses. The thorax is the locomotor region, while in the abdomen the primi- tive segmentation is most marked. Through the body as an axis runs the alimentary canal, the mouth being on the under surface of the head, while the vent is at the tip of the abdomen. Above the diges- tive tract lies the heart, which in many forms has a chamber in each of several somites of the body; that is, the heart is segmented. On the floor of the body, below the alimentary canal, is the nervous system, which ex- hibits this segmentation in a more marked degree. In each segment there is a paired enlargement or ganglion from which nerves go to the various organs of the seg- ment. These ganglia of the successive segments are con- nected with each other by a double nerve-cord, so that all are in communication with each other. At the front end of the body one of these nerve-cords passes on one side of the oesophagus, the other on the other, and above it they unite with a large compound ganglion, the so- called brain. In this way a part of the nervous system. 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 Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
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