516 BIOLOGY. 



deposited in the external tegument or rind, and the stem 

 is converted into stone LttJiozoa, Lithophyta, Corals. 



This calcareous earth contains the most general acid, or 

 the carbonic, and thus oxygen combined with the inor- 

 ganic carbon, while the bones contain phosphoric acid, 

 oxydized gelatine. 



3172. As the calcareous earth is, properly speaking, 

 only a granular deposit in the tegument, like it is in the 

 cartilages of the higher animals; so is it not to be regarded 

 as a free worm-tube, but as the body itself. Meanwhile 

 it forms a tube open above, from which the mouth of the 

 animal projects. 



3173. As the animal ramifies, so also do the stony 

 tubes increase, and there originates a phytoidal or plant- 

 like stem, but one consisting of a stony mass. 



3 1 74. Thus the Coral is the earth-animal, and indicates 

 the globular or osseous mass under its first grade of for- 

 mation in the animal kingdom. 



But there are also Polyps, whose stem only originates 

 through saccular inversion of the upper portion of the 

 animal's body ; yet this is only distinct in the soft stems. 

 In most of the species, where a separate intestine is to be 

 found, it is probably only the upper part of the body which 

 is so inverted. Meanwhile there are some, whose intestine 

 forms a circle by returning upon itself, and opens into an 

 anus. 



3175. If then the Infusoria are the vitellus or seed of 

 the animal kingdom ; in like manner the Corals are its 

 ova. The carbonate of lime is the shell surrounding the 

 albumen, while the animal or intestine is the vitellus 

 Albumen-animals. 



3176. Nature forms these living ova, when she takes 

 vitellus and albumen out of the sea-slime, invests them 

 with a shell derived from the earth, and hatches them, 

 after they have been vivified by sun and air. 



Class 3. Absorbent, Involucral Animals. 



3177. Did the former animals remain in the con- 

 dition of ova, from want of a perfect vascular system ; 



