ANTIIOZOA ASTEROIDA. 



143 



teum.* A cross section of the stem or of a principal branch 

 will show the layers to be disposed concentrically round a 

 central medulla, the layers more or less compactly pressed 

 according to the nature of the species (fig. 32), The whole 

 section presents a certain resemblance to a similar section of 

 a dicotyledonous tree (fig. 33) : the medulla in position and 

 outward appearance is a pith ; the horny axis is the wood ; 

 and the fleshy crust has been denominated the bark ; j" — nor 

 perhaps could fault be found with this language, since it is 

 sufficiently illustrative, had it not been the mother of some 

 very erroneous notions, and a great means of their projiagation 

 and continuance. Thus Linna3us, in his definition of Gor- 

 gonia, calls the axis a vegetating stem : and as if this was not 

 sufficiently exjjlicit, we find Pallas entering into detail, and 

 telling us that the concentric circles are produced by succes- 

 sive transmutations of the fleshy crust, in the same manner 

 that the circles of the wood of trees are formed by transfor- 

 mations of the inner layers of the bark.j And this opinion, 

 if we may judge from their language, has been adopted by 



Fig. 32. 



Fig. 33. 



\ .v,-^. 



.1, Vl/':'-!,,::- ":*-:'!i.il5)n''l;:l|Mil^ 





* " L'ecorce des Gorgoniees ne se lie pas immediatement a I'axe, elle en est 

 separee par une membrane d'une nature particuliere, si mince dans le genre Gorgonia, 

 qui'l est tres-difficile de I'apercevoir ; elle est plus apparente dans les Plexaures et les 

 Eunicees." — Polj^). Corall. Flex. p. 391. Couch, lib. cit. p. 47. 



t Lin. Syst. 1829. 



+ Elench. p. 162. He seems, however, to have had his suspicions that the theory 

 was questionable, for he adds — " Quanquam diversissima corticis natiu:a, ejusdemque 

 facUis a ligno separatio, suggerere possent : hujus strata potius ex deposito intus sueco 

 fieri, aut lignum, prout ossa animalium sanguineorum intra periosteum, generari, 

 augeri, durescere." 



