. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 214 ACTINIARIA Textfigs. 200—201. Sicyonis tuberculata. Transverse section of tentacle near its base (fig. 200) and of the middle part of the sphincter (fig. 201). section of sphincter in its middle part). The ectoderm of the tentacles is on the base of the outside low, on tlie inside a little thicker, more upwards the ectoderm of the outside is also thicker. It contains rather numer- ous to numerous nematocysts, 19—34x2,5 // large, and ver\' numerous spirocysts of variable length, from 22 X 2 to 55 X 5 /< (3 specimens ex
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 214 ACTINIARIA Textfigs. 200—201. Sicyonis tuberculata. Transverse section of tentacle near its base (fig. 200) and of the middle part of the sphincter (fig. 201). section of sphincter in its middle part). The ectoderm of the tentacles is on the base of the outside low, on tlie inside a little thicker, more upwards the ectoderm of the outside is also thicker. It contains rather numer- ous to numerous nematocysts, 19—34x2,5 // large, and ver\' numerous spirocysts of variable length, from 22 X 2 to 55 X 5 /< (3 specimens examined). The tentacles are devoid of longitudinal muscles on the abaxial side at the base, more upwards there are solitary muscle-meshes in the mesogloea (textfig. 200, transverse section of tentacle near its base), and in the distal part, above the swelling of the mesogloea, numerous meshes of the same size as those at the adaxial size, where the muscle-meshes are numerous also at the base. The muscle meshes are more or less delicate and often elongated in radial direction. The mesogloea is considerably thicker than the ectoderm, excepting at the apex of the tentacles. The radial muscles of the oral disc recall the outer tentacle-lacking parts of the longitudinal muscles of the tentacles and form thin meshes, elongated in the di- rection from the ectoderm to the endoderm. At the insertions of the mesenteries they are interrupted by thicker mesogloeal balks. In the vicinity of the actinopharynx the muscle meshes are small and few. The ectoderm of the actinopharynx is rather high, strongly pig- mentous and contains numerous, typical nematocysts, 24—31 X 2,5 ;^ in size, and rather numerous nematocysts with discernible basal part to the spiral thread (size 24—29x5 ft. 3 specimens examined). The arrangement of the mesenteries is rather peculiar and shows a tendency to an octomerous development, in as much as often 16 pairs are perfect; there are besides some fewer or more n
Size: 812px × 3078px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectscienti, bookyear1921
