254" DISSEMINATION OF PLANTS. 



New vegetations But that which ought to excite our attention, is the pro» 

 that appear when duclion of a new vegetation in a place which has undergone 

 ground is dif- fome very great changes. In all cafes when the furface of a 

 turbed. place has been altered either by tne falling or removal of the 



earth, by opening roads through forefts, or by draining marfhes, 

 plants are fure to be found in the following year, which did 

 not exift there before, while the former fpecies difappear, ex- 

 cept a few cofmopolites, if the expreffion may be allowed, 

 which, though they re-appear, undergo a remarkable altera- 

 tion (Di6i. d'Agr. de UEncycl. meth. art. Climat.) When a 

 wood is grubbed up, the forefl plants ceafe to grow, and thofe 

 natural to tilled ground immediately germinate. Labat no- 

 tices (fee Vol. I. p,. 386.) that, in his time, at the Antilles, 

 as foon as the ground was cleared, its furface became covered 

 with purflane. In thofe places where charcoal is made, in 

 forefts at a great diftance from any habitation, I daily obferve 

 plants, different from thofe which were formerly there, and 

 which are natives either of dry paftures or cultivated lands, 

 fuch as the (vergerette) of Canada, the annual veronicas, &c. 

 Forfter, in his voyages with Cook, took notice of feveral iflets 

 in the middle of the fea, fimply rocks of coral, on which the 

 firft rudiments of vegetation were forming. In the low val- 

 leys of the downs of Holland, I have gathered a fatyrion and 

 an ophrys, natives v of the fummits of the Alps and the plains 

 of Spitzbergen (Satyrium viride, L. Ophrys monorchis, L.) 

 But thefe downs, according to the obfervations of Cit. D£can- 

 dolle, (Ann, d'Agr. T. XIII. p. 372.) are not of very ancient 

 Are thefe pro- origin. How is the introduction of thefe two plants, which 

 duced by the are naturally provided with very limited means of multiplica- 

 cther plants. t * on > *° De accounted for? I have expreffed a wifh in the 

 Encyclopedic, that the new iflands formed by volcanos, and 

 particularly thofe near Santorini fhould be examined. One of 

 our rood accurate obfervers is on the point of vifiting the lat- 

 ter, (See d' Olivier, T. II. p. 238). The new one produced 

 by the eruption of 1707 to 1711, does not yet fhew any ap- 

 pearance of vegetation, the air is ftill mephitic ; that which 

 arofe in 1573 has fome traces of vegetation, particularly fome 

 graffes, and a fmall fig tree ; the latter may have been depo- 

 fited by fome bird, but by what means were the graffes con- 

 veyed ? 



4 It 



