724 PHILOSOPHICAL TRANSACTIONS. [aNNO IJjd. 



external appearance of wood, yet the internal structure differs in the most essen- 

 tial points from vegetables. 



In order to prove this, I have compared different sections of the gorgonia with 

 correspondent sections both of sea and land plants, and find they differ in the 

 following particulars : the longitudinal sections of the stems of the larger fuci, 

 such as the fucus digitatus, esculentus, nodosus, and saccharinus, appear com- 

 posed of parallel jointed tube-like figures, the joints of which are composed of 

 gland-like cells ; these tubular appearances, when highly magnified, are dis- 

 covered to be connected together by transparent reticulated fibres, or very mi- 

 nute transverse tubes, interwoven with the upright ones. In a horizontal sec- 

 tion, the ranges of cells, which look like rays from the centre, as they approach 

 the bark, become smaller and smaller, and most probably correspond with the 

 minute pores which cover the outer surface of the plant ; tor when the sides of 

 the dry stems are soaked in water, they quickly imbibe it, and soon become full 

 of a gelatinous liquor ; all which is totally different from the texture of the gor- 

 gonia. 



We come now to compare them with land plants, such as shrubs, like to 

 which they are generally supposed to grow. The gorgonia has no regular series of 

 hollow fibres or little tubes, in what is called the wood, either longitudinal or 

 horizontal. It appears composed of a sort of irregular laminae like horn ; the 

 fibres of which take no certain direction, iior preserve in any two places the same 

 thickness. It has no series of utricular vessels, as the transverse vessels of wood 

 are called by Malpighi ; or insertions as they are called by Dr. Grew. These are 

 essentially necessary, as forming a communication from the bark and the internal 

 parts of the wood quite through. On the contrary, the concentric circles of the 

 gorgonia have no connection with each other ; they run like so many parallel 

 curves, and are connected by no insertions or utricular vessels ; but to all ap- 

 pearance have been formed by separate depositions of concreting matter. So 

 the shells of snails and oysters are formed ; their respective animals throw out 

 periodically the osseous juice or testaceous matter, which adheres to the former 

 shell and concretes, and thus successive layers are produced. In the same man- 

 ner I suppose the concentric circles of the gorgonia to be formed, successive 

 layers of juice exuding from the fleshy tubes that surround the hard part or bone 

 of the animal. Thus the stem of the gorgonia verticillata, or Minorca white 

 sea-feather, is composed of different layers of a shell-like substance, (see fig. 6,) 

 where a broken part of the stem is represented, and a piece of it magnified, to 

 show that there is evidently no more communication between the different 

 laminae than there is between those of an oyster-shell. In a transverse section 

 of the gorgonia pretiosa, or true red coral, Donati has observed, Philos. Trans., 

 vol. 47, p. 97, [Abridgement, vol. x, p. 158.] "Different lines or annual 



