280 tHE WORLDt 



and of various sizes, some of them are so minute that they cannot 

 be seen without a microscope. They are congregated together 

 like other zoophytes, each individual being connected to a com- 

 mon body, so that what is received by any one goes to the nour- 

 ishment of the whole. The stony matter, or hard substance of 

 the zoophyte, is formed as are the bones and nails in man, by se- 

 cretions from the animal substance, by which they are penetrated 

 and invested, The cells of the coral, therefore are not built up 

 by the polypi, as they are called, in the same manner as the wax- 

 en cells of the bee. We may often observe little patches of 

 yellowish calcareous matter on sea-weed, or shells thrown upon 

 the shore, this upon examination appears to be a kind of delicate 

 net-work, but when examined with a microscope the substance is 

 found to be full of pores, and if the examination is made while 

 i\\e,fiustra or calcareous matter is immersed in the water, each 

 pore will appear to be the opening of a cell, whence issues a tube 

 with several long arms or feelers; sometimes these expand, and 

 then suddenly close and are withdrawn into the cells, then issue 

 forth again. Thus each individual of the group occupies its own 

 particular cell, but the whole constitutes one family of polypes 

 connected by a common integument, or fleshy or gelatinous sub- 

 stance which invests the whole. Figure 1, of the wood-cut be- 

 low exhibits the series of cells of the fiustra, systematically 



arranged. Each cavity is the receptacle of a polype shown with 

 the tenlacula, or feelers, expanded in fig. 2, and contracted into 

 its cell in fig. 3. These views are from drawings made by Mr. 

 Lister, and figured by Dr. Mantell, in his excellent Wonders of 

 Geology." The animals just described are members jf the same 



