. A manual of elementary zoology . Zoology. THE PIGEON 415 with the active life of the bird and the rapid metabolism Blood v s 1 which it necessitates. We have already seen how the respiratory organs provide the ample supply of oxygen which such metabolism demands. The red corpuscles are oval and nucleated. The heart has four chambers, two auricles and two ventricles, there being no sinus venosus or conus arteriosus. The impure blood returned by the venae cavse to the right auricle passes into the right ventricle through an opening guarded by a muscular valve without chordae tendinese. It
. A manual of elementary zoology . Zoology. THE PIGEON 415 with the active life of the bird and the rapid metabolism Blood v s 1 which it necessitates. We have already seen how the respiratory organs provide the ample supply of oxygen which such metabolism demands. The red corpuscles are oval and nucleated. The heart has four chambers, two auricles and two ventricles, there being no sinus venosus or conus arteriosus. The impure blood returned by the venae cavse to the right auricle passes into the right ventricle through an opening guarded by a muscular valve without chordae tendinese. It is then driven by the pulmonary artery to the lungs, whence it returns by the pulmonary veins to the left auricle, passing thence through two membranous valves with chordae tendinese to the left ventricle, by which it is driven into the single aortic arch. The openings of the aorta and pul- monary artery are guarded each by three semilunar valves. The aortic arch bends over to the right side, giving off at its apex right and left innominate arteries, from each of which arise a carotid and a subclavian. The latter is exceedingly short, breaking up immediately into brachial and pectoral branches. The further course of the arteries is shown in the diagram (Fig. 305). The venous system is shown in the same figure. There are three venae cavae, as in the frog. Each superior vena cava is formed by the union of a jugular, a brachial,. Fig. 305.—A diagram of the principal arteries and veins of a pigeon.—From Thomson, after Parker. ao., Aortic arch ; , brachial artery ; brachial vein ; C, carotid artery; cm., coccygeo-mesenterjc vein ; , dorsal aorta; F., femoral vein adjoining femoral artery ; hepatic veins; il., in- ternal iliac artery and vein ; , inferior vena cava,;y., jugular vein ; La., left auricle; P., right pulmonary artery J Pea., pectorabartery ; ', pectoral vein'; , right auricle; , hypogastric vein; renal vein'; sc, sciatic
Size: 1116px × 2239px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1920
