14 THE GEOGRAPHY OF PLANTS. 



by professor E. Forbes, supposes that plants 

 were originally created in certain spots, (called 

 " centres of creation,") each containing its 

 peculiar group of species, and that from these 

 spots they have become gradually diffused ; the 

 extent of such diffusion depending partly on 

 the peculiar adaptation of the plants them- 

 selves, and also being in many cases very much 

 modified by geological changes. We are not, 

 however, prepared to subscribe to this theory, 

 however ingenious ; a much larger array of 

 facts must be produced in its support before 

 it can claim to be regarded as a truth. We 

 should rather be inclined to say, with one of 

 our poets, 



" Jehovah spake 



And Earth, an infant, naked as she came 

 Out of the womb of Chaos, straight put on 

 Her beautiful attire, and deck'd her robe 

 Of verdure with ten thousand glorious flowers, 

 Exhaling incense ; crowri'd her mountain-heads 

 With cedars, train 'd her vines around their girdles, 

 And pour'd spontaneous harvests at their feet." 



In entering somewhat more at large into this 

 subject, we will consider separately the influence 

 of situation, climate, and attitude. First, then, 

 as to SITUATION and SOIL. These materially 

 influence the distribution of plants. Some 

 require a moist soil others a dry one : some a 

 high elevation others are found only in the 

 plains : some in the clefts of rocks others in the 

 richest pastures others only in sandy wastes : 

 some grow immersed in the ocean others are 

 on dry walls and roofs. The southern slope of a 

 hill is generally clothed with different plants to 



