INTRODUCTION. 7 



tree or flower is vastly inferior to that of some of the 

 humblest lichens and mosses. Although these plants 

 occupy but a very subsidiary and unimportant position 

 among the vegetation which surrounds us in our daily 

 walks, and are concealed in isolated patches in the woods 

 and fields by the luxuriance of higher and more conspicu- 

 ous plants, yet they constitute the sole vegetation of 

 very extensive regions of the earth's surface. Every part 

 of the globe, within a thousand feet of the line of per- 

 petual snow, is redeemed from utter desolation by these 

 plants alone. Above the valleys and the lower slopes 

 which form the step of transition from plain to mountain 

 inhabited by prosperous and civilized nations is the 

 domain of mist and mystery, the region of storm a 

 world which is not of this world, where God and nature 

 is all in all, and man is nothing ; and in this unknown 

 region there are immense tracts familiar to the eye of 

 wild bird, to the summer cloud, the stars and meteors of 

 the night strange to human faces and the sound of 

 human voices, where the lichen and the moss alone luxu- 

 riate and carpet the sterile ground. The grandest and 

 sublimest regions of the earth are adorned with garlands 

 of the minutest and humblest plants ; they are the tapes- 

 try, the highly-wrought carpeting laid down in the ves- 

 tibules of nature's palaces. If we look at a map of 

 the world, we see that Europe and Asia are held together 

 as it were by a huge ridge or back-bone of mountain ele- 

 vation, which, although suffering partial interruption, 

 may be roughly described as continuous from one ocean 

 to another. It begins with the mountains of Biscay in 

 Spain, passes on through the Pyrenees with a slight 



