File:Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct - for the use of schools and colleges (1870) (14779629311).jpg

Identifier: outlinesofcompar00agas (find matches)
Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges
Year: 1870 (1870s)
Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884
Subjects: Physiology, Comparative Zoology
Publisher: London : Bell & Daldy
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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, or stig-mata, into two great lateral tubes, which subdivide and ramifythrough the body; the tracheae are lined with a soft mucous ~ *- - membrane, and covered externally with a dense, shining,serous coat; between these is interposed an elastic fibroustunic, formed of a cartilaginous filament rolled into a spiralform, like the spiral vessels in plants. This admirable struc-ture, affording as it does one of those striking examples ofcreative wisdom and design, extends through all the ramifi-cations of the tracheae, giving the necessary elasticity andpatency to tubes destined to convey air, and to ramify likeblood-vessels through all parts of the head, antennae, palpi,legs, tarsi, wings, muscular, nervous and digestive systems ; 224 OF EESPIRATTON. the stigmata, or spiracles, are provided with muscles to openand close them, and with valves, processes, and hairs, va- HeaO. 1st pair of legs 1st segment ofthe thorax. Origin of thewings. 2d pair of legs.3d pair of legs. Trachese. Spiracle.
Text Appearing After Image:
Vesicular airsacs. Fig. 234.—Respiratory apparatus of the Nepa cinerea. riously modified in the different families, to protect them fromthe entrance of foreign bodies. The abdominal segments ofthe body exhibit rythmic contractions and expansions during:respiration, which are well seen in the dragon-fly, and resem-ble the muscular movements of the thorax and abdomen duringthe same act in the pulmonated vertebrates.—T. W.) KESPIRATlOTf. 220 § 386. In the lower vertebrata provided with 1 rings the/ form a single or- gan Luii;:

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