. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. ACTINIARIA 193. Fig. 183 and, as Danielssen states, of an almost triangular form. In their uppermost part they 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 // in size, and numerous mucus-cells. The meso- gloea is in the proximal part thin or of ordinary' thickness, corresponding to the different state of contraction, but swells out in the region of the sphinc
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. ACTINIARIA 193. Fig. 183 and, as Danielssen states, of an almost triangular form. In their uppermost part they 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 // in size, and numerous mucus-cells. The meso- gloea is in the proximal part thin or of ordinary' thickness, corresponding to the different state of contraction, but swells out in the region of the sphincter and there forms a thick layer; it contains small protoplasma-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 Tealidiutn cingulatum (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 w) of considerable size (74^—93x12—13/!/), which are, however, smaller than those of Tea The Ingolf-Expedition. V. 9. J. Please note that these image
Size: 1351px × 1849px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectscienti, bookyear1921
