. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. 38 MEDUSA. II. of very large polygonal cells almost as broad as high. They are very much vacuolated, containing only a very insignificant amount of protoplasm, concentrated in the corners of the cells. Each one of the cells contains a small nucleus and i—4 oval nematocysts of different sizes. In the broad nematocyst pads the cells are irregularly arranged, but upwards on the exumbrella thej' gradually arrange themselves into 4—3—2 rows, so that the dilatated parts become pointed upwards an
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. 38 MEDUSA. II. of very large polygonal cells almost as broad as high. They are very much vacuolated, containing only a very insignificant amount of protoplasm, concentrated in the corners of the cells. Each one of the cells contains a small nucleus and i—4 oval nematocysts of different sizes. In the broad nematocyst pads the cells are irregularly arranged, but upwards on the exumbrella thej' gradually arrange themselves into 4—3—2 rows, so that the dilatated parts become pointed upwards and, finally, are continued in the nettle ribs. The latter consist of cells quite similar to those found in the dilatated parts, but in the ribs the cells are arranged in one single row. In the nettle ribs there may sometimes be as many as 7 or 8 nematocysts in one single cell. — In its proximal part the dilatated nematoc3'St-bearing epithehum is broader than the corresponding ten- tacular bulb (see the tangential section, textfig. 33), and it is, for the most part, separated from the endoderm of the bulb by a gelatinous layer of considerable thickness (radial section, textfig. 34); only in the innnediate neighbourhood of the velum, the exumbral jelly is confined to a ' ' thin supporting lamella. The nematocyst-bearing epithelium may, accordingly, only very improperly be designated as part of the tentacular bulb. As a matter of fact, the three rudimentary. K^a ^^ aaced. bulbs are completely "internal", exclusively consisting of an endo- dermal dilatation of the gastrovascular system, only close by the ^S* 33" Fig- 34- velum, on both sides of the latter, approaching the ectodermal Figs. 33—34. Hybocodon proli/er. Rudimentary marginal bulb. — Fig. 33. Tangential longitudinal epithelium. As far as the tentaculiferous bulb is concerned, we section, showing the greatly vacuolated ectoderm. i i n ^i i .,, • i n ... ,. ,. ,, .^ ,' , I- ,; , may well speak ab
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
