I shall not repeat here what may be found in several excellent treatises on the coca;[648] I need only say that the original home of the species in America is not yet clearly ascertained. Gosse has shown that early authors, such as Joseph de Jussieu, Lamarck, and Cavanilles, had only seen cultivated specimens. Mathews gathered it in Peru, in the ravine (_quebrada_) of Chinchao,[649] which appears to be a place beyond the limits of cultivation. Some specimens from Cuchero, collected by Poeppig,[650] are said to be wild; but the traveller himself was not convinced of their wild nature.[651] D’Orbigny thinks he saw the wild coca on a hill in the eastern part of Bolivia.[652] Lastly, M. André has had the courtesy to send me the specimens of _Erythroxylon_ in his herbarium, and I recognized the coca in several specimens from the valley of the river Cauca in New Granada, with the note “in abundance, wild or half-wild.” Triana, however, does not admit that the species is wild in his country, New Granada.[653] Its extreme importance in Peru at the time of the Incas, compared to the rarity of its use in New Granada, seems to show that it has escaped from cultivation in places where it occurs in the latter country, and that the species is indigenous only in the east of Peru and Bolivia, according to the indications of the travellers mentioned above. +Dyer’s Indigo.+—_Indigofera tinctoria_, Linnæus. The Sanskrit name is _nili_.[654] The Latin name, _indicum_, shows that the Romans knew that the indigo was a substance brought from India. As to the wild nature of the plant, Roxburgh says, “Native place unknown, for, though it is now common in a wild state in most of the provinces of India, it is seldom found far from the districts where it is now cultivated, or has been cultivated formerly.” Wight and Royle, who have published illustrations of the species, tell us nothing on this head, and more recent Indian floras mention the plant as cultivated.[655] Several other indigoes are wild in India. This species has been found in the sands of Senegal,[656] but it is not mentioned in other African localities, and as it is often cultivated in Senegal, it seems probable that it is naturalized. The existence of a Sanskrit name renders its Asiatic origin most probable. +Silver Indigo+—_Indigofera argentea._ This species is certainly wild in Abyssinia, Nubia, Kordofan, and Senaar.[657] It is cultivated in Egypt and Arabia. Hence we might suppose that it was from this species that the ancient Egyptians extracted a blue dye;[658] but perhaps they imported their indigo from India, for its cultivation in Egypt is probably not of earlier date than the Middle Ages.[659] A slightly different form, which Roxburgh gives as a separate species (_Indigofera cærulea_), and which appears rather to be a variety, is wild in the plains of the peninsula of Hindustan and of Beluchistan. +American Indigoes.+