IX THE VEGETABLE CREATION. 365 



in it, and that nitrogen is in the air surrounding it, and 

 frequently mixed with it also. 



Under the influence of sunshine, we have now seen 

 these elements uniting into a mysterious bond, and the 

 result is the formation of a cellular tissue, which pos- 

 sesses many of the functions of the noblest specimens of 

 vegetable growth. But let us examine the progress. 

 The bare surface of a rock rises above the waters 

 covered over with this green slime, a mere veil of deli- 

 cate net-work, which, drying off, leaves no perceptible 

 trace behind it ; but the basis of a mighty growth is 

 there, and under solar influence, in the process of time, 

 other changes occur. 



After a period, if we examine the rock, we shall find 

 upon its face little coloured cups or lines with small 

 hard discs. These, at first sight, would not be taken for 

 plants, but on close examination they will be found to be 

 lichens. These minute vegetables shed their seed and 

 die, and from their own remains a more numerous crop 

 springs into life. After a few of these changes, a sufficient 

 depth of soil is formed, upon which mosses begin to 

 develope themselves, and give to the stone a second 

 time a faint tint of green, a mere film still, but indicating 

 the presence of a beautiful class of plants, which, under 

 the microscope, exhibit in their leaves and flowers many 

 points of singular elegance. These mosses, like the 

 lichens, decaying, increase the film of soil, and others of 

 a larger growth supply their places, and run themselves 

 the same round of growth and decay. By and by, 

 funguses of various kinds mingle their little globes and 

 umbrella-like forms. Season after season plants, perish 

 and add to the soil, which is at the same time increased 

 in depth by the disintegration of the rock over which 

 it is laid, the cohesion of particles being broken up by 

 the operations of vegetable life. The minute seeds of 

 the ferns floating on the breeze, now find a sufficient 

 depth of earth for germination, and their beautiful 



