52 ALONG THE FLORIDA REEF. 



The boats were now gradually nearing Bush 

 Key, with its scraggy trees, when Dick ex- 

 claimed : 



" Why, there's a cigar in the water ! " 



"So it is," said Harry, nearly tumbling over- 

 board in an attempt to reach it. 



" Sold again ! " laughed Tom, who had secured 

 one ; " it's only a stick." 



" You'd find them hard to smoke, boys," said 

 the doctor. " They are more useful than all the 

 cigars that could be sent over here from Havana. 

 They are the seeds of the mangrove tree, that 

 you see over on Bush Key. The reef of the 

 State of Florida has been formed mainly by the 

 corals and the mangroves." 



"Tell us how, doctor," said Harry, who was 

 always ready for information. 



" Suppose," said the doctor, " this clear water 

 on which we are drifting should be visited by a 

 single egg of the star-shaped coral called the 

 Axtnva. It settles on a bit of shell. In a few 

 days some tentacles spring out, and the tiny 

 polyp seems only a solitary sea-anemone. Then 

 a little growth of lime, secreted by the anemone, 



