92 THE HARMONIES OF NATUEE. 



the rider on his horse, who is more at a loss to find his way 

 through the impenetrable thicket than through the mazes of a 

 primeval forest, as it prevents him from looking round, and 

 affords him no solid stem on which he might climb to ascertain 

 his position. Thus these thistle wildernesses, which owe their 

 origin to the casual introduction, perhaps, of a single seed, have 

 spread like a cancer over tracts of land larger than many a 

 German principality, and have become one of the great nuisances 

 of the country, as they not only usurp the place of useful grasses, 

 but afford, moreover, a secure retreat to the jaguar, and to the 

 still more dangerous banditti, who alone are acquainted with 

 their labyrinthine paths. 



When we consider the variety and efficacy of the means which 

 Providence uses for the dispersion of plants, the lightness of 

 many seeds, particularly of the lower cryptogamous plants, the 

 feathery or wing-like appendages of others, the constant agency 

 of the winds and currents, and the scarce less active interference 

 of the birds, the four-footed animals, and man, we cannot 

 wonder that, wherever vegetation can possibly exist, it should 

 take possession of the naked soil. The process is more rapid 

 in the humid countries of the tropical zone, more tardy under 

 the chilling influence of the wintry north ; but in course of time 

 even the most desolate lava-fields, in the higher latitudes, hide 

 their black waves of rugged stone under a more friendly gar- 

 ment, for which they are originally indebted to the seed-bearing 

 winds. 



First, lichens, mushrooms, mosses ; then, such thrifty herbs as 

 are content to feed upon nothing, have to prepare a scanty layer 

 of mould or humus for the reception of more pretentious guests. 

 Gradually some small stunted shrub makes its appearance here 

 and there in some peculiarly favoured spot, and, after all, re- 

 quires vast powers of endurance to maintain itself on the nig- 

 gard soil, exposed to the perpetual enmity of wind and 

 weather. This paves the way for a more vigorous and fortunate 

 race ; and as every year adds something to the vegetation on 

 the mountain's side, and opposes increasing obstacles to the 

 winds, the falling leaves and decaying herbage accumulate more 

 and more, until dwarfish trees first find a sufficiency of soil to root 

 upon, and finally the proud monarch of the forest spreads out 

 his powerful arms, and raises his majestic summit to the skies. 



