

ON THE NATURE AND USES OF THE PRIMAEVAL VEGETATION 



OF THE EARTH. 



By Robert Dickson, M.D., F.L.S. 



In a former article (p. 146) we made some remarks on the geometrical prin- 

 ciples which had been observed in the construction of the members of the leading 

 divisions of the vegetable kingdom, and on the inferences which might be thence 

 drawn respecting the Deity and his works. If we turn our attention to the princi- 

 ple which regulates the distribution of plants over the surface of the globe, and 

 assigns to each country its precise and peculiar kind of vegetation, we shall not 

 find it less worthy of our consideration, or less fraught with lessons of wisdom and 

 proofs of benevolence. The prevailing or predominating species of plants which 

 form the vegetable covering of the earth, give to each country its characteristic 

 aspect, determine the nature of the wild animals and insects which frequent it 

 or live there, and, as Humboldt justly remarks, " produce the most important ef- 

 fects upon the social state of the people, the nature of their manners, and the de- 

 gree of developement of the arts of industry." 



Let any one be conveyed from Britain to some island in a tropical latitude, 

 and at the first glance he will perceive that he is surrounded by vegetable forms 

 very different in appearance and structure from those of his native land. Instead 

 of the Oaks, the Ashes, the Elms, and the Sycamores, with their enormous stems 

 and wide-spreading branches, sometimes covering nearly a quarter of an acre, he 

 will strain his eyes in looking upwards at the leaf-crowned summit of some slender 

 branchless stem that seems to pierce the sky. Perchance he may recognize forms 

 akin to the Ferns of his own country, but surpassing them in size and variety as 

 much as the lakes of America and the mountains of India surpass in vastness and 

 height those of Europe. 



Again, let him be conveyed to the polar regions : there he will find a few trees 

 — such as Firs and Birches of a dwarfish size — braving the rigors of these climes, 

 but an utter absence of those shrubs and flowers of larger growth, which make 

 our woods and lawns so gay and fragrant ; the flowers to be there met with being 

 such as are never seen in Britain, save on the summits of our loftiest mountains. 



K the individual be possessed of an inquiring and reflecting spirit, he will soon 

 discover that the most general and influential of the causes which occasion these 

 different and opposite phenomena, is temperature ; and might be led to imagine 

 that if some convulsion of nature were to effect a change in the temperature of 

 Britain, he might see its surface clothed with the vegetation of the tropics, if that 

 change consisted in an elevation of temperature ; or, if the reverse, he might see 

 the alpine vegetation descend from the mountains and inhabit the plains, or mi- 



