THE ANCIEIS'T AND MODEEN FLOEAS OF MONTPELLIEE. 209 



The most important and direct influence of man is by cultivation. 

 '' Wherever lie has established himself, he has deeply modified the 

 aspect of vegetation ; he has broken up large tracts, covered them 

 with plants foreign to the country, and, by his constant care, pro- 

 tected against the attacks of the indigenous vegetation, those plants 

 necessary for his wants or his industry. But this introduction of 

 cultivated plants does not enter within the scope of our essay ; we 

 only take into consideration those species which, once confided to 

 the soil, are abandoned to their own resources, and must maintain 

 themselves, without other aid, against the enemies of all kinds which 

 surround them." 



But direct efforts have not been wanting on the part of botanists 

 really to naturalize exotic plants in various parts of the region by 

 sowing and planting them in localities where they were supposed to 

 be likely to succeed. Nissole in the seventeenth century, Gouan and 

 Amoreux in the eighteenth, and Moquin-Tandon in the present one, 

 carried on the operation on a large scale. Gouan and Amoreux 

 especially have left records of about 900 species so treated ; but after 

 a careful research, Dr. Planchon cannot discover that a single one 

 has established itself, or is now to be found in the localities indicated, 

 if it was not already naturally there. It is true that, on examining 

 the lists, there appears to have been very little discernment on the 

 part of the experimenters in the selection of species or of stations. 

 " They have taken into account neither the favourite stations of these 

 species, nor the aspects which they usually prefer, nor the chemical 

 or physical condition of the soil, nor the association of the vegeta- 

 tion which surrounds or shades them." It is probable also that the 

 number of seeds sown, or of roots planted, was always very limited. 

 " It is, therefore, not surprising that the rare individuals which suc- 

 ceeded in germinating, isolated amidst the rightful possessors of the 

 soil, should rapidly have been smothered by them " But it is ob- 

 served, " notwithstanding the imperfection of these attempts, it 

 must be admitted that some species amongst the number must have 

 met with the conditions favourable for their development. Why 

 have they not spread and established themselves in the country ? 

 It is evidently because the naturalization of a plant meets with many 

 more difficulties than one would suppose without experience. There 

 are indeed very few that triumph over all the obstacles opposed to 

 their establishment. If a species does not early show its tendency 

 to naturalization, if it decs not sow or multiply itself on its arrival 



