. A manual of zoology. 248 MANUAL OF ZOOLOGY /us. Appended to the chyle stomach at its anterior end are in many insects a number of tubular pouches, the hepatic caeca {axe). At the junction of the chyle stomach with the small intestine, or further back, there open a number (from 2 to over 100) of narrow tubular appendages, the Mal- pighian tubes (map), which are the organs of renal ex- cretion. The intestine is usually elongated, its posterior portion is dilated to form a wide rectum, which opens in the anal aperture on the last segment. Anal glands producing an odoriferous secretion often ope
. A manual of zoology. 248 MANUAL OF ZOOLOGY /us. Appended to the chyle stomach at its anterior end are in many insects a number of tubular pouches, the hepatic caeca {axe). At the junction of the chyle stomach with the small intestine, or further back, there open a number (from 2 to over 100) of narrow tubular appendages, the Mal- pighian tubes (map), which are the organs of renal ex- cretion. The intestine is usually elongated, its posterior portion is dilated to form a wide rectum, which opens in the anal aperture on the last segment. Anal glands producing an odoriferous secretion often open into the rectum. The organs of respiration are a sys- tem of fine branching tubes, the tra- chea (Fig. 147), which communicate with the exterior through valvular apertures known as stigmata situated at the sides of the segments. These tracheae form a completely ramify- ing system which conveys the air to all the parts of the body. The wall of the tubes is strengthened by a series of spirally wound chitinous fibres, each fibre or thread making from one to four or five turns around the trachea?. In some insects, mainly those adapted for active flight, the tracheal system is dilated in certain parts of the body to form large air sacs. In the aquatic larva? of some insects there is a series of soft external simple or divided processes â â the tracheal gills â attached to the abdominal segments, and richly supplied with trachea? which have no communication with the Fig. 147.â Periplaneta. View of the arrangement of the principal trunks of the tracheal system. (After Miall and TJenny.) '. 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 Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmillan Company; London, Macmillan & Co. ,Lt
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