22 THE FAIRY-LAND OF SCIENCE. 
provided with little hairs, by means of which they 
swim to new resting-places. You will learn the dif- 
ference between the animal which builds up the red 
coral as its skeleton, and the group of animals which 
build up the white; and you will look with new in- 
terest on our piece of white coral, as you read that 
each of those little cups on its stem with delicate divi- 
sions like the spokes of a wheel has been the home of 
a separate polyp, and that from the sea-water each little 
jelly animal has drunk in carbonate of lime as you 
drink in sugar dissolved in water, and then has used 
it grain by grain to build that delicate cup and add to 
the coral tree. 
We cannot stop to examine all about coral now, we 
are only learning how to learn, but surely our speci- 
men is already beginning to grow interesting; and 
when you have followed it out into the great Pacific 
Ocean, where the wild waves dash restlessly against 
the coral trees, and have seen these tiny drops of jelly 
conquering the sea and building huge walls of stone 
against the rough breakers, you will hardly rest till 
you know all their history. Look at that curious 
circular island in the picture (Fig. 3), covered with 
palm trees ; it has a large smooth lake in the mid- 
dle, and the bottom of this lake is covered with 
blue, red, and green jelly animals, spreading out their 
feelers in the water and looking like beautiful flow- 
ers, and all round the outside of the island similar 
animals are to be seen washed by the sea waves. 
Such islands as this have been built entirely of the 
skeletons of the coral animals, and the history of the 
way in which the tiny creatures added to them inch 
