1 88 From Matter to Man. 



In explanation of these phenomena, it is supposed 

 that during the processes of reproduction the pseudo- 

 podia retract, and the animal resolves itself into a solid 

 jelly round its nucleus. It then remains stationary 

 for a time, acting as a sort of mould, while it secretes 

 lime on its back, which then hardens. As the organ- 

 ism grows, chamber is added to chamber until the 

 structure is of the most complex description. The 

 reticularia are thus assumed to be compound animals, 

 each chamber housing a complete individual ; but 

 this is mere conjecture at present as their mode of 

 reproduction is only imperfectly known. 



The most astonishing circumstance concerning them 

 is their number. Though so small, they are so plenti- 

 ful that it is computed an ounce of the sand at the 

 port of Gaeta contains no less than a million and a 

 half of their skeletons ; while, along with the kindred 

 radiolaria, whole islands — Barbadoes, for example, 

 are composed of them. 



Molluscs. — The crystalline enclosures of the molluscs 

 are formed in a somewhat similar way to the reticu- 

 laria ; the carbonate of lime or silica being merely 

 secreted by their external cells. 



Corals. — The most conspicuous of the animals which 

 are largely crystalline in structure are the corals. The 

 typical coral, as we see it in museums, is a beautiful 

 lime formation branching like a tree. In its living 

 state, the coral is a compound animal containing a 

 hard internal core or skeleton composed of calcareous 

 secretions. This core is enveloped by a fleshy cover- 



