. A manual of zoology. Zoology. Fig. 506. Fig. 5°7- Fig. 506.—Balanoiylo^sus koTiialewskii*' (irom KorschcU-Hcider, after A. Agassiz). dh, dorsal blood-vessel; e, proboscis; g, region; k, gill region; kr, collar; vb, ventral blood-vessel. Fig. 507.—A, Tornarla larva of Balanoglossus (after Morgan), a, apical plate; ac, preoral part of ciliated band; ic', hc', be', ccelomic pouches; m, mouth; p, pjostoral part of ciliated band B, C, two stages of Balanoglossus with direct development (after Bateson). a, anus,, be, branchial clefts; c, collar; dc, digestive part of alimentary canal; in,
. A manual of zoology. Zoology. Fig. 506. Fig. 5°7- Fig. 506.—Balanoiylo^sus koTiialewskii*' (irom KorschcU-Hcider, after A. Agassiz). dh, dorsal blood-vessel; e, proboscis; g, region; k, gill region; kr, collar; vb, ventral blood-vessel. Fig. 507.—A, Tornarla larva of Balanoglossus (after Morgan), a, apical plate; ac, preoral part of ciliated band; ic', hc', be', ccelomic pouches; m, mouth; p, pjostoral part of ciliated band B, C, two stages of Balanoglossus with direct development (after Bateson). a, anus,, be, branchial clefts; c, collar; dc, digestive part of alimentary canal; in, intestine; nc, 'notochord'; p, proboscis. which they arise; in the nerves (neurotomes), the skeleton (sclerotomes), the blood-vessels, and in the excretory organs (nephrotomes). In the higher vertebrates this metamerism is best seen in the embryonic stages. In part the absence of external segmentation has its cause in the heter- onomy (p. 126) of the body and the obliteration of segmental boundaries, consequent upon the union of somites into regions, of which at least three 29. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
