o 



CLASSIFICATIONS OF ZOOPHYTES. 77 



gelatinous, and the external a complete membrane, so formed as to cover the stem 

 in the manner of a sheath or tube. That the other Gorgonife consist of a horny 

 stem coated by a membrane, which is hardened by carbonate of lime. That the 

 sponges are of a natme similar to the horny stems of the Gorgoniee, and only 

 differ from these and from each other by the quality of texture. And lastly, 

 that the Alcyonia are likewise composed of a soft flexible membranaceous sub- 

 stance, very similar to the cortical part of some of the GorgonicC ; and in like 

 manner slightly hardened by carbonate, mixed with a small portion of phosphate 

 of lime. 



" From this mass of evidence we collect, in general, that the varieties of bone, 

 shell, coral, and the numerous tribe of Zoophytes with which the last are con- 

 nected, only differ in composition by the nature and quantity of the hardening 

 or ossifying principle, and by the state of the substance with which this princi- 

 ple is mixed or connected ; the gluten, or jelly, which cements the particles of 

 carbonate or phosphate of lime, and the membrane, cartilage, or horny substance 

 which serves as a basis, appearing to be only modifications of the same sub- 

 stance, which progressively graduates from a viscid liquid, or gluten, into a ge- 

 latinous substance, which again, by increased inspissation, and by the more or 

 less perfect degrees of organic arrangement, forms the varieties of membrane, 

 cartilage, and horn, which, it seems, form the peculiar differences of the several 

 species." Abst. Phil. Trans, i. 25-26. There is a very full analysis of Hatch- 

 ett's paper in Thomson's Syst. of Chem. v. p. 539, et seq. The paper itself 

 will be found in Phil. Trans, abridg. xviii. p. 706. 



Raspail has ascertained that a large proportion of iron enters into the com- 

 position of the Alcyonella, which he thinks may be derived from the habitat, the 

 zoophyte developing itself upon ferruginous rocks. The iron holds the same po- 

 sition in the polypidom, that the carbonate of lime does in the Oculinae, or the 

 crystals of silex in the sponges. Its great proportional quantity may be esti- 

 mated from the following experiment " Un fragment sec du Polypier faisait 



devier de trois degres la nouvelle aiguille aimantee, construite par notre collegue, 

 M. Saigey, quoique ce fragment ne presentat a raiguille qu'une surface d'un cen- 

 timetre environ. Cette deviation paraitra enorme si Ton veut se rappeler que 

 I'Alcyonelle est une substance spongieuse extraordinairement legere ; ajoutes a 

 I'importance de ce resultat que le fer parait y exister a I'etat de trioxide, puisqu' 

 avant comme apres I'incineration, la substance est egalement rougeatre, et qu'en 

 consequence son influence sur I'aiguille aimantee serait infiniment faible, si le fer 

 existait en faible quantite dans son tissu lache et spongieux." — Mem. de la Soc. 

 d'Hist. Nat. iv. p. 119. 



" Non tamen, post tot ac tantos scriptores, pigebit meam quibusdam locis 

 posuisse sententiam. Neque enim me cujusquam sectae, velut quadam super- 



stitione imbutus, addixi : sicut ipse pliurium in unum confero inventa, 



ubicumque ingenio non erit locus, curse testimonium meruisse contentus." — 

 QuintiUan. iii. i. 



