132 CHARLES DARWIN 



Cordillera, across the continent. I saw it in unfrequented 

 spots in Chile, Entre Rios, and Banda Oriental. In the 

 latter country alone, very many (probably several hundred) 

 square miles are covered by one mass of these prickly plants, 

 and are impenetrable by man or beast. Over the undulating 

 plains, where these great beds occur, nothing else can now 

 live. Before their introduction, however, the surface must 

 have supported, as in other parts, a rank herbage. I doubt 

 whether any case is on record of an invasion on so grand 

 a scale of one plant over the aborigines. As I have already 

 said, I nowhere saw the cardoon south of the Salado; but 

 it is probable that in proportion as that country becomes 

 inhabited, the cardoon will extend its limits. The case is 

 different with the giant thistle (with variegated leaves) of 

 the Pampas, for I met with it in the valley of the Sauce. 

 According to the principles so well laid down by Mr. Lyell, 

 few countries have undergone more remarkable changes, 

 since the year 1535, when the first colonist of La Plata landed 

 with seventy-two horses. The countless herds of horses, 

 cattle, and sheep, not only have altered the whole aspect of 

 the vegetation, but they have almost banished the guanaco, 

 deer and ostrich. Numberless other changes must likewise 

 have taken place; the wild pig in some parts probably re- 

 places the peccari ; packs of wild dogs may be heard howling 

 on the wooded banks of the less-frequented streams; and 

 the common cat, altered into a large and fierce animal, in- 

 habits rocky hills. As M. d'Orbigny has remarked, the in- 

 crease in numbers of the carrion-vulture, since the introduc- 

 tion of the domestic animals, must have been infinitely great ; 

 and we have given reasons for believing that they have ex- 

 tended their southern range. No doubt many plants, besides 

 the cardoon and fennel, are naturalized; thus the islands 

 near the mouth of the Parana, are thickly clothed with 

 peach and orange trees, springing from seeds carried there 

 by the waters of the river. 



agreed that the cardoon and the artichoke are varieties of one plant. I may 

 add, that an intelligent farmer assured me that he had observed in a deserted 



which I have mentioned a few lines lower down, under the title of giant 

 thistle. Whether it is a true thistle I do not know; but it is quite different 

 from the cardoon; and more like a thistle properly so called. 



