G. GORGONIA. 
197 
All the Gorgonias appear in their organisation to 
consist of two substances ; the interior is sometimes 
horny and hard, sometimes more soft and brittle, like 
the blea ( alburnum ) of some trees and of many biennial 
plants. This interior substance seems to be composed 
of concentric layers, formed of longitudinal fibres. M. 
Lamark has given it the name of Are (Axis). When 
the rind or exterior is thick, the axe is proportionably 
smaller and more compact ; but larger and of a softer 
consistence, when the rind is thin. The surface, be- 
sides, is marked with lines and pores, by means of 
which, doubtless, a communication is kept up between 
the outer and innermost parts of the animated mass. 
In short, this axe in Polypidoms appears destined to 
perform functions analogous to those recognized in 
the skeletons of vertebrous animals, or the articulated 
and horny envelopements of insects ; and it undoubt- 
edly makes part of the animal, as the animal cannot 
exist without it. 
The growth of the axe in the Gorgonias appears to 
proceed by layers, placed one upon the other. They 
frequently enclose in their interior, portions of the 
fleshy envelope, by some unknown cause deprived 
of life; this phenomenon seems to be effected in 
the same manner that the bark of trees is renewed 
when a part has previously experienced any injury. 
The rind envelopes the axe throughout its whole 
extent; it is fleshy in the living state of the Poly- 
pidom, and we feel justified in the presumption 
that it is then irritable and susceptible: by desic- 
cation it becomes chalky and earthy, and will dis- 
solve in acids ; it always effervesces with them. 
