. The biology of birds. Birds. THE BIOLOGY OF BIRDS 'AS Fig. 34.—Windpipe and lungs of bird. T., tongue; hy„ horns of hyoid ; gl., glottis ; TR., trachea ; , sterno- tracheal muscles attached to breastbone ; SY., syrinx ; BR., bronchial tubes; l., cavity of lung; AS., meso- bronchus leading into the abdominal air-sac- mesothelium. Now the endoderm of the pouch gives off numerous hollow buds in a complicated way and these form the " bronchial tree " of the lung. They branch and branch, but the image of a tree is inaccurate since the branches unite by a network of inter-com- munic
. The biology of birds. Birds. THE BIOLOGY OF BIRDS 'AS Fig. 34.—Windpipe and lungs of bird. T., tongue; hy„ horns of hyoid ; gl., glottis ; TR., trachea ; , sterno- tracheal muscles attached to breastbone ; SY., syrinx ; BR., bronchial tubes; l., cavity of lung; AS., meso- bronchus leading into the abdominal air-sac- mesothelium. Now the endoderm of the pouch gives off numerous hollow buds in a complicated way and these form the " bronchial tree " of the lung. They branch and branch, but the image of a tree is inaccurate since the branches unite by a network of inter-com- municating passages. Eventually in the fully-developed lung no bronchial twigs end blindly. Of the complicated internal con- figuration of the endodermic lin- ing which forms something like an irregular labyrinth, the meso- dermic envelope of the lung gives no indication whatsoever. To sum up, the special adapta- tions of the bird's respiratory system are—(i) the large internal surface of the lungs, due to the complex branching of the bronchi; (2) the great development of air- sacs which increase the efficiency of the lungs ; (3) the fixing of the lungs to the ribs so that the move- ments of these in flight helps the expulsion and inrush of air. § 6. Excretion All vital activity seems to in- volve—whatever else it involves —^the metabolism of proteins, namely, the nitrogenous carbon- compounds which are invariably present in living matter. Take albumin as a sample. Every cell. 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 Thomson, J. Arthur (John Arthur), 1861-1933. New York : Macmillan
Size: 803px × 3114px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectbirds, bookyear1923
