The allied species are _Solanum Commersonii_ of Dunal, of which I have already spoken; _S. maglia_ of Molina, a Chili species; _S. immite_ of Dunal, a native of Peru; and _S. verrucosum_[118] of Schlechtendal, which grows in Mexico. These three kinds of _Solanum_ have smaller tubers than _S. tuberosum_, and differ also in other characteristics indicated in special works on botany. Theoretically, it may be believed that all these, and other forms growing in America, are derived from a single earlier species, but in our geological epoch they present themselves with differences which seem to me to justify specific distinctions, and no experiments have proved that by crossing one with another a product would be obtained of which the seed (not the tubers) would propagate the race. Leaving these more or less doubtful questions of species, let us try to ascertain whether the common form of _Solanum tuberosum_ has been found wild, and merely remark that the abundance of tuberous solanums growing in the temperate regions of America, from Chili or Buenos Ayres as far as Mexico, confirms the fact of an American origin. If we knew nothing more, this would be a strong presumption in favour of this country being the original home of the potato. The second cause of error is very clearly explained by the botanist Weddell,[119] who has carefully explored Bolivia and the neighbouring countries. “When we reflect,” he says, “that on the arid Cordillera the Indians often establish their little plots of cultivation on points which would appear almost inaccessible to the great majority of our European farmers, we understand that when a traveller chances to visit one of these cultivated plots, long since abandoned, and finds there a plant of _Solanum tuberosum_ which has accidentally persisted, he gathers it in the belief that it is really wild; but of this there is no proof.” We come now to facts. These abound concerning the wild character of the plant in Chili.