Distribution of Plants, 525 



the soil on which they are found) that they could be assembled 

 originally in one station ; or that one single part of the world 

 could afford varieties of climate, soil, and situation sufficient 

 for the support of plants which now are found in the most 

 opposite regions of the earth. It is physically impossible that 

 the same vegetable productions should be found on the sandy 

 downs of New Holland, or in the forests of North America, 

 and on the granitic peaks of the Himalayah chain. However 

 strange this theory may appear, nevertheless it is but just to 

 mention that it was the opinion of the founder of scientific 

 botany. Linn^us very ingeniously, though, in my opinion, 

 unconvincingly, endeavours to prove that plants were origin- 

 ally dispersed from one localit}^ In maintenance of this 

 theory, he supposes the primary seat of plants to have been 

 in a warm climate (Armenia or Thibet), comprehending a 

 lofty mountain range, on which the plants of different regions 

 were congregated, and from thence spread over the world. 

 (Oratzo de Telluris hahitabilis Licremento.) If such were the 

 case, we might expect, in the regions in the heart of Asia, to 

 find traces of the vegetable productions of America, New 

 Holland, or Southern Africa ; since from the mountain ridge, 

 and the circumjacent plains of Asia, according to this sup- 

 position, they originally migrated. It is much more rational 

 to suppose that the creation of them was universal, modified 

 and regulated to suit the character of the soil, composition of 

 the rocks, and temperature of the climate, in which they were 

 intended to multiply. To assist their dispersion, he calls in 

 the aid of winds, rivers, birds, &c. ; and makes mention of 

 many curious contrivances in the vegetable structure to enable 

 them to project their seeds to a distance : and supposes, since 

 the seeds of cryptogamous plants are so minute, that they 

 would be conveyed by the agency of the winds to an incal- 

 culable distance. To this theory some strong objections may 

 be offered: — 1st, That vegetables could not be dispersed, 

 without a soil calculated to receive and nourish the seeds ; 

 2d, Though the winds are undoubtedly able to convey the 

 seeds of many plants to a great distance, especially those of 

 the class Syngenesia and natural order Compositae, yet of 

 many others they cannot effect the dispersion for even a 

 single mile. I have myself seen, in this county (Yorkshire), 

 a bank covered with the Aquilegia vulgaris, which, though 

 exposed to the most violent action of the winds, never spread 

 over the neighbouring fields. This opinion we cannot, there- 

 fore, reasonably admit as the true one : the progressive steps 

 by which vegetation advances are extremely slow; and it 



