. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. Fig. 183 Fig. 184 and, as Danielssen states, of an almost triangular form. In their uppermost part thej- are provided with distinct gonidial tubercles. Anatomical description. The pedal disc has a rather thick cuticle. The ectoderm of the column is somewhat low and contains rather numerous nematocysts 22—24 X about 4 fi in size, and numerous mucus-cells. The meso- gloea is in the proximal part thin or of ordinary thickness, corresponding to the dilTerent state of contraction, but swells ou
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. Fig. 183 Fig. 184 and, as Danielssen states, of an almost triangular form. In their uppermost part thej- are provided with distinct gonidial tubercles. Anatomical description. The pedal disc has a rather thick cuticle. The ectoderm of the column is somewhat low and contains rather numerous nematocysts 22—24 X about 4 fi in size, and numerous mucus-cells. The meso- gloea is in the proximal part thin or of ordinary thickness, corresponding to the dilTerent state of contraction, but swells out in the region of the sphincter and there forms a thick layer; it contains small protoplasnia-poor cells. The endodermal circular muscles are weak, the mesogloeal sphincter, on the other hand, is very strong and juts out, during certain states of contraction, as a strong thickening towards the ectoderm, about as the sphincter of Tealidium cingulatmn (Hertwig 1882 PI. 6 fig. 2). In the upper part and in the greater part of its length it occupies almost the whole breadth of the mesogloea, proximally it decreases rapidly and takes up only the inner part of the mesogloea. The mus- cle meshes are very small, in certain parts very close, in other parts se- parated by larger lamellae of the mesogloea. Any distinct stratifica- tion of the sphincter is, however, not to be seen (textfig. 183). The ectoderm of the ten- tacles is very high and contains very numerous spirocysts of very vari- able size, unto 53 X 4—6 /i; on the other hand, the typical nematocysts are very sparse and 26—29 X 4—(5)/^ in size. In the swollen basal part, on the outside of the outermost tentacles, there is a specific stinging organ developed (textfig. 184), which I have also observed in Tealidium jungerseni. This battery contains very numerous, closely packed nemato- cysts (fig. 184 «) of considerable size (74—93x12—13//), which are, however, smaller than those of Tea-. Fig. 185 Fig. 186 Textfigs. 1
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
