6 INTRODUCTION. 



were all modelled with a skill and finish that left nothing 

 to be added. 



And as in early geological epochs they occupied so con- 

 spicuous a position, so now in the annals of physical geo- 

 graphy they are entitled to a prominent place. With the 

 exception of the grasses nature's special favourites they 

 are the most abundant of all plants, possessing inconceiv- 

 able myriads of individual representatives in every part 

 of the globe, from which unfavourable conditions exclude 

 all other vegetation ; and thus they contribute, far more 

 than we are apt from a superficial observation to ima- 

 gine, to the picturesque and romantic appearances ex- 

 hibited by scenery, and to the formation of that richly 

 woven and beautifully decorated robe of vegetation which 

 conceals the ghastly skeleton of the earth, and hides from 

 our view the rugged outlines and primitive features of 

 nature. They are the first objects that clothe the naked 

 rocks which rise above the surface of the ocean ; and 

 they are the last traces of vegetation which disappear 

 under degrees of heat and cold fatal to all life. Their 

 structure is so singularly varied and plastic, that they 

 are adapted to every possible situation. In every country 

 they form an important element in the number of plants, 

 the proportion to flowering plants decreasing from, and 

 increasing towards the poles. Taking them as a whole, 

 and in regard to their size, they occupy a larger area of 

 the earth's surface than any other kind of vegetation. 

 There are immense forests of trees here and there in 

 different countries, realizing Cowper's wish for "a bound- 

 less contiguity of shade;" there are vast colonies of 

 flowering plants ; but the range of the most ubiquitous 



