Page:Popular Science Monthly Volume 7.djvu/13

Rh formerly fashionable, if one such could be made to stand of itself erect, and have the frill around the upper end to project in a circle. But we must be more particular than this. The upright part, that which is called by naturalists the column, is hollow, like a sack. Its base is really a sucking-surface, enabling it to adhere to any hard object. By this sucking base it can glide, or travel along, much like a snail.



And as it thus moves, it can keep its flower spread out, and its many tentacles in constant play—in fact, fishing on the way. Their movement is, however, very slow. Indeed, a "snail-pace" would be alarmingly fast for an actinia. We have watched them attentively, and have found that an inch in an hour was a very satisfactory performance. At the top is an opening, called the oral cavity, which, in the rosea, is surrounded just inside with a beading of little dots. This opening may be called the mouth, because the food is passed at this aperture into the stomach, which is a cylindrical sac, suspended below, and reaching about half-way down the great cavity of the column. Around the oral cavity, and external to it, is a plain surface, which is technically known as the "disk." Around the disk, on its outer edge, is the fringe of tentacles. Each one of these is a little hollow cylinder, opening into the great cavity of the column immediately under the edge of the disk. In fact, these tentacles, or feelers, connect with the interior of the stem of the Anemone, just as the fingers of a glove do with the interior of the same. We should also mention that, at the bottom of the sac, which is here called the stomach, is an opening into the general cavity. Now, around this suspended stomach, that is, between its outer wall and the inner wall of the column, is a system of compartments in series. These vary as to number in the different species. By looking at the cut showing a cross-section of an actinia's stem, we observe that six of these compartments are complete, and reach from the stomach to the walls of