III. INTRODUCED SPECIES. 8S 



otherwise not have been cultivated in England, as the 

 Senccio squaUdus and Sisymbrium polyceratium. Even 

 botanical herbaria may have been the introducing source 

 of some occasional stragglers. M. De Candolle suspects 

 the fully established Rumex pulclier and Polygonum Con- 

 volvulus, and also several of the Chenopodia, to be of 

 foreign origin in Britain ; ideas which may rather sur- 

 prise those English botanists who are so averse to the 

 elimination of doubted* species from our native flora. 

 The same Botanist also thinks, with much probability of 

 correctness here, that Coronojms didyma and Mercurialis 

 annua are only naturalised aliens in England. But the 

 views of the illustrious Botanist of Geneva will be spe- 

 cially mentioned under succeeding sections. 



3. Vietvs of M. Alphouse De Candolle. 



In the second volume of the Geographie Botanique 

 M. Alplionse De Candolle gives his results from a close 

 examination of the three earlier volumes of the Cj'bele 

 Britannica, made with especial reference to the conflicting 

 opinions about the aboriginal nativity of the species in 

 Britain, or their introduction into this country by human 

 agency. He compares together the recorded opinions of 

 English botanists, and also takes largely into account the 

 apparent conditions of the same species on the Continent 

 of Europe ; adding thereto such other evidences of a less 

 direct kind, chiefly philological and biblical, as may be 

 conceived likely to throw any light upon this obscure 

 subject. He then gives his readers the benefit of his 

 own views, founded upon an examination and comparison 

 of the various data thus brought together. 



Under these circumstances, it seems to be well worth 

 while to devote some pages to an exposition of the views 



