. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 312 CO^MPARATIVE ANATOMY of the adult, which probably functions as an accessory heart. Direct connjBctions exist between the second and third afferent and efferent arteries. Towards the end of the larval period, the second efferent bran- chial artery increases considerably in relative size, and the fourth arterial arch also becomes larger. By a reduction of the anasto- mosis with the third arch, the fourth carries most of the blood for the pulmonary artery, and the latter thus now contains more venous than arterial blo
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 312 CO^MPARATIVE ANATOMY of the adult, which probably functions as an accessory heart. Direct connjBctions exist between the second and third afferent and efferent arteries. Towards the end of the larval period, the second efferent bran- chial artery increases considerably in relative size, and the fourth arterial arch also becomes larger. By a reduction of the anasto- mosis with the third arch, the fourth carries most of the blood for the pulmonary artery, and the latter thus now contains more venous than arterial blood. When branchial respiration ceases, the anasto- moses between the afferent and efferent branchial arteries no longer consist of capillaries, but a direct connection between them be- comes established (Fig. 252). Finally, the connection between the. Fig. —Aetekial Akches of an Adult Salamaiirlm maculosa, shown SPREAD OUT. (After J. E. V. Boas.) CO, tr, trimcus arteriosus ; 1 to 4, the four arterial arches ; ce, external carotid ; erf, " carotid gland " ; ci, internal carotid. The fourth arterial arch, which gives rise to the pulmonary artery [Ap], has increased considerably in size relatively, and IS only connected by a delicate ductus Botalli (t) with the second and third arclies ; JRA, root of the aorta ; of, (Esophageal vessels. first and second branchial arches disappears, the former giving rise to the carotid and the latter forming the large aortic root; an anastomosis remains throughout life, however, between the fourth arch, which forms the pulmonary artery, and the second and third arches. This is usually spoken of as the duchLS Botalli. The third arch varies greatly in its development; it may be present on one side only, or may even be entirely wanting. In the larvae of Anura there are also four "afferent branchial arteries present on either side, but these are connected with the corresponding efferent vessels by capillaries only, there being n
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
