54 ALONG THE FLORIDA REEF. 



lao-oon formed within the shallow circle ; as the 

 reef becomes higher, sea-weeds and corallines are 

 added ; every particle of refuse adds to the up- 

 building of this curious island ; and now, just as 

 the dry layers, or top-dressings, appear above 

 the waves, along comes Dick's ' cigar.' The larger 

 end of the mangrove seed strikes the sand or 

 mud collected on the reef, the waves drive it still 

 farther on, and, touching the soil, it sends out 

 little shoots. These soon obtain a foothold, and 



Multiplication of polyps by spontaneous fission. 



thus a mangrove tree is started. These being self- 

 propagating by shoots and rootlets, a growth in 

 time may extend around a whole island. Other 

 waste matter of the sea is accumulated, the in- 

 fluence of winds and tides changes the surface, 

 and Nature furnishes suitable plants to flourish 

 in the new soil which the decay of vegetable 



