Archive image from page 169 of The development of the frog's. The development of the frog's egg; an introduction to experimental embryology . developmentoffro00morg Year: 1897 154 DEVELOPMENT OF THE FROG'S EGG [Ch. XIV cliial arches have greatly enlarged, and the efferent and afferent vessels are now also united to each other in each arch by small vessels (Fig. 47) or capillary tubes. The efferent vessels of these two arches are also in communication with the dorsal aorta of their respective sides. There is thus established at this time a circulation of blood from the heart to the dorsal aort
Archive image from page 169 of The development of the frog's. The development of the frog's egg; an introduction to experimental embryology . developmentoffro00morg Year: 1897 154 DEVELOPMENT OF THE FROG'S EGG [Ch. XIV cliial arches have greatly enlarged, and the efferent and afferent vessels are now also united to each other in each arch by small vessels (Fig. 47) or capillary tubes. The efferent vessels of these two arches are also in communication with the dorsal aorta of their respective sides. There is thus established at this time a circulation of blood from the heart to the dorsal aorta by way of the first and second branchial arches. In the third and fourth branchial arches the efferent vessels have appeared. In the third arch the beginning of an affer- FiG. 47. —AFi. Afferent branchial vessel. CV. Anterior cardinal vein. EFi. Effer- ent branchial vein. G. Pneumogastric nerve. JV. Inferior jugular vein. L. Capillary loop connecting afferent and efferent branchial vessels. N. Notochord. O. Aorta. P. Pericardium. PH. Pharynx. SU. Suckers. V. Fourth ven- tricle. (After Marshall.) ent vessel is seen (Fig. 46). In the hyoid arch blood-vessels appear, as we have seen, at an early stage of development and seem to correspond to those in the branchial arches, but after developing to a certain extent, they begin to degenerate. In the mandibular arch no vessels have appeared at the time when the larva leaves its capsule. Soon after this time a vessel de- velops in this arch, and a small diverticulum arises from the dorsal aorta (Fig. 46, B, MV), and later the two vessels unite. The origin of the heart has been described, but as yet the
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