The Sea Anemone has a cylindrical body, attached at one end by a sucker to rocks or stones at no great depth, and a flat circular disk at the other, with the mouth in its centre: the mouth, which is surrounded by a series of tubular, smooth-edged, radiating tentacles, resembles a blossom. The soft smooth body consists of two layers, as may be seen in the sections of an Actinia (fig. 129). The outer layer generally contains red matter, the inner one is of muscular fibre, and contains a great cavity, in which a somewhat globular bag or stomach is suspended. The space between the stomach and the cylindrical body of the animal is divided into chambers by perpendicular radiating partitions, consisting of thin plates or lamellæ. The mouth, which opens at once into the stomach, imbibes sea-water; and the hollow tentacles surrounding it being perforated at their extremities, and in communication with the chambers immediately below them, also imbibe the sea-water and convey it into the chambers; and the vibrations of the innumerable cilia, with which all the cavities of the animal are lined, keep them perpetually bathed with the respiratory medium mixed with nutrient juices from the coats of the stomach.[27] [Illustration: Fig. 129. Actinian polype.] The Sea Anemone is monœcious and oviparous; the eggs are formed and fertilized in the lower parts of the perpendicular lamellæ or radiant plates; but they are hatched within the visceral cavity, and the larvæ issue from the mouth. The Actiniæ are also propagated by buds. They have as great a power of repairing injuries as the Hydræ, and like them too, though generally fixed, they can creep about by means of their expanded suctorial disk, and even float on the surface of the water. In many species the tentacles, as well as the body, are brightly coloured. The Actinia sulcata, an inhabitant of the British Channel, is of a deep crimson, with from 100 to 200 grass-green tentacles. The tints are owing to coloured particles in minute globules, that lie under the transparent skin of the animal and its tentacles.