"I can see now--it is _not_ rock.

What is it, Dr.Sandford ?" "Lichen." "What is that, sir ?" "It is one of the lowest forms of vegetable life.

It is the first dress the rocks wear, Daisy." "But what does it live on ?" "Air and water, I suppose." "I never knew that was a vegetable," said Daisy musingly.

"I thought it was the colour of the rock." "That goes to prepare soil for the mosses, Daisy." "O how, Dr.Sandford ?" "In time the surface of the rock is crumbled a little by its action; then its own decay furnishes a very little addition to that.

In favourable situations a stray oak leaf or two falls and lies there, and also decays, and by and by there is a little coating of soil or a little lodgment of it in a crevice or cavity, enough for the flying spores of some moss to take root and find home." "And then the moss decays and makes soil for the ferns ?" "I suppose so." Daisy stood looking with a countenance of delighted intelligence at the great boulder, which was now to her a representative and witness of natural processes she had had no knowledge of before.