. A manual of zoology. Zoology. Fig. io8.—Larvse of Strongylocenirotus lividus (after Boveri). Left a blaslula witli mesenchyme formation; right a gastrula with differentiated mesenchyme. entoderm becomes widened Ijy the secretion of gelatinous substance, and from the entoderm isolated cells push into this jelly; thus there arises a middle layer, the mesenchyme (fig. io8), somewhat similar to gelatinous connective tissue, from which certain organs either wholly or in part take their origin. The mesenchyme can be formed before the beginning of gastrulation or after that process has been complet
. A manual of zoology. Zoology. Fig. io8.—Larvse of Strongylocenirotus lividus (after Boveri). Left a blaslula witli mesenchyme formation; right a gastrula with differentiated mesenchyme. entoderm becomes widened Ijy the secretion of gelatinous substance, and from the entoderm isolated cells push into this jelly; thus there arises a middle layer, the mesenchyme (fig. io8), somewhat similar to gelatinous connective tissue, from which certain organs either wholly or in part take their origin. The mesenchyme can be formed before the beginning of gastrulation or after that process has been completed (fig. io8; cf. p. 74).. Fig. ioq.—Formation of tlie mesothehum and crclom of Sagitla. A. From the bottom of the gastrula arise two folds, which divide the archcnteron into the permanent digestive tract and the ccelomic diverticula. B. The separation is almost completed by the pushing up of the folrls. ak, outer, mk, middle, ik, inner germ-layer; nik\ somatic layer; mk'-, splanchnic layer; Ih, body-cavity. Mesothelium.—In the second case the mesoderm may preserve the epithelial character of the two primary germ-layers, and is called meso- thelhmi. It is cut off from the entoderm, the mode of development being shown in the worm Sagilta (fig. 109). When the gastrula of Sagitta has been formed two folds arise from the archenteric walls opposite the. 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
