Anatomy of Gorgonid^. 107 



eter of the cross section of a spicule. This peculiarity of 

 structure seems to be characteristic of this species, as all the 

 spicules which are properly situated on the slide exhibit it. 



The spicules are embedded in the fundamental substance 

 throughout the zoanthodeme below the ectodermal investment, 

 and are always enclosed in an apparently structureless mem- 

 brane which remains after the spicules have been removed by 

 the action of acids. This investing sac,' if such it can be called, 

 not only invests the spicule as a whole but also follows the out- 

 line of every projection, be it spine, nodule, or tubercle, which 

 may be upon the surface of the spicule, so that after the 

 spicule is dissolved, we have a perfect mold of its minutest 

 external configuration. There has been some discussion as to 

 whether spicules are purely calcareous masses containing no 

 organic matter within the investing sacs above described, or 

 partially calcareous structures containing organic matter in 

 intimate union with the earthy salts through the whole mass 

 of the spicule. KoUiker holds to the former opinion, while 

 Pouchet and Myevre maintain the latter.'^ Analogy would 

 seem to indicate the former as the correct view. The proofs 

 given by the defenders of the latter view are not satisfactory. 

 They claim that afcer prolonged action of acid upon the spic- 

 ules, there remains a substance which they describe as " une 

 masse de substance organique, transparente, a peine granu- 

 leuse, gardant d'une facon tres-reconnaissable la forme du 

 spicule." 



Such a substance does, in fact, remain even after the most 

 prolonged immersion in strong acid, but whether it is organic 

 or not is another question. The fact is that those spicules 

 which are near the surface of the zoanthodeme dissolve out 



1 See further discussion of Spicules, in connection with third species 

 described. (Muricea . 



2 "Nos observations faites sur les spicules des deuK especes d'Alcyons, sont 

 absolument opposees a, cette maniire de voir, et coniirnient au contraire ce 

 qu'avait annonce Queket en 1854; que dans les spicules, chaque molecule de 

 matiere caicaire est dans un etat d'intime union avec la base organique." — Con- 

 tribution a TAnatomie des Alcyonaires, p. 292. 



