Page:The Zoologist, 1st series, vol 1 (1843).djvu/306

278 sons of the year, but appear most abundantly about September, October and November. Ellis has figured similar excrescences on the G. Abietina, PI. 16 in his 'History of Zoophytes.' These protuberances, on dissection, prove to be hollow, and to be partly filled with a white granular substance. They are composed of—first, the external fleshy bark, with its membrane; next, the membrane of the axis, which is raised, and in contact with the bark; then the white granular matter and the denuded axis.

The next part to be considered is the axis or skeleton, which is the frame-work that gives shape and consistence to the whole. It is horny, solid, elastic and fibrous, and has its centre occupied by a white pith, which extends to all the branches. It varies in size according to the age of the specimen, but is considerably influenced by the situation in which it grows, being more slender and irregular the nearer it approaches the shore, and the older portions are more solid than the younger. This increase in the size of the axis depends rather on the integrity of the fleshy bark, than on any action in the part itself, for if, from accident or the incrustation of corallines, the bark be rubbed off, the axis ceases to increase as far as the denudation extends, while all above and below increases as before. The axis, in a transverse section, will be found to be composed of concentric layers, marked by lighter and darker lines, similar to what is observed in the same section of an exogenous stem. The axis of the Gorgonia, however, differs from wood in several important particulars, having neither the radiating medullary rays, nor the cellular structure, which renders wood so beautiful an object under the microscope.

In a longitudinal section, the concentric layers are as apparent as in the transverse. It is longitudinally fibrous, and rends very freely in that direction. In this section, in different parts of the substance of the axis, patches of grey matter are frequently to be found; most commonly on the lower portions of the trunk, and in the axillæ of branches, especially when two rise close to each other. In the bend of the branches it is very common to observe several layers of it formed in regular succession, separated by thin portions of the axis, and in a specimen before me there are five such strata, alternating with the dark fibres of the axis. This appears to be the substance supposed by Ellis to be the remains of a portion of the fleshy bark, which had been enclosed between the horny layers by previous denudation and regrowth. He says, "we frequently meet with layers of calcareous matter enclosed between circles, which is evidently nothing else but the decayed flesh of the animal, which has been covered and