He says that the word _yam_ means “to eat,” in several negro dialects on the coast of Guinea. It is true that two travellers nearer to the date of the discovery of America, whom Humboldt quotes,[306] heard the word _igname_ pronounced on the American continent: Vespucci in 1497, on the coast of Paria; Cabral in 1500, in Brazil. According to the latter, the name was given to a root of which bread was made, which would better apply to the manioc, and leads me to think there must be some mistake, more especially since a passage from Vespucci, quoted elsewhere by Humboldt,[307] shows the confusion he made between the manioc and the yam. _D. Cliffortiana_, Lam., grows wild in Peru[308] and in Brazil,[309] but it is not proved to be cultivated. Presl says _verosimiliter colitur_, and the _Flora Brasiliensis_ does not mention cultivation. The species chiefly cultivated in French Guiana, according to Sagot,[310] is _Dioscoreæ triloba_, Lam., called Indian yam, which is also common in Brazil and the West India Islands. The common name argues a native origin, whereas another species, _D. cayennensis_, Kunth, also cultivated in Guiana, but under the name of _negro-country yam_, was most likely brought from Africa, an opinion the more probable that Sir W. Hooker likens a yam cultivated in Africa on the banks of the Nun and the Quorra,[311] to _D. cayennensis_. Lastly, the _free yam_ of Guiana is, according to Dr. Sagot, _D. alata_ introduced from the Malay Archipelago and Polynesia. In Africa there are fewer indigenous _Dioscoreæ_ than in Asia and America, and the culture of yams is less widely spread. On the west coast, according to Thonning,[312] only one or two species are cultivated; Lockhardt[313] only saw one in Congo, and that only in one locality. Bojer[314] mentions four cultivated species in Mauritius, which are, he says, of Asiatic origin, and one, _D. bulbifera_, Lam., from India, if the name be correct. He asserts that it came from Madagascar, and has spread into the woods beyond the plantations. In Mauritius it bears the name _Cambare marron_. Now, _cambare_ is something like the Hindu name _kam_, and _marron_ (marroon) indicates a plant escaped from cultivation. The ancient Egyptians cultivated no yams, which argues a cultivation less ancient in India than that of the colocasia. Forskal and Delile mention no yams cultivated in Egypt at the present day. To sum up: several _Dioscoreæ_ wild in Asia (especially in the Asiatic Archipelago), and others less numerous growing in America and in Africa, have been introduced into cultivation as alimentary plants, probably more recently than many other species. This last conjecture is based on the absence of a Sanskrit name, on the limited geographical range of cultivation, and on the date, which appears to be not very ancient, of the inhabitants of the Pacific Isles.