In the first place we ought to make quite sure what Hippocrates understood under the name λεῦκαι. A disease of the Skin no doubt; but of what particular nature it was, would seem not to be so easy to determine. According to _Coac. praenotion._ (Vol. I. p. 321.) Hippocrates distinguished a λεύκη συγγενής and a λεύκη μὴ συγγενής (λεύκη inborn, and not inborn), the latter attacking individuals only after puberty. _Hesychius_ says λεύκη, ἄνθος τι τῶν περὶ τὸ σῶμα γινόμενον, ἄλφος δὲ λευκή τις ἐν τῷ σώματι. (λεύκη—white leprosy, an eruption coming out on the exterior parts of the body, but ἄλφος—dull-white leprosy, a form of λεύκη in the body). _Galen_, _Definit. med._ (Vol. XIX. p. 140) λευκή ἐστιν ἡ ἐπὶ λευκὸν χρῶμα τοῦ σώματος παρὰ φύσιν μεταβολή. (λεύκη is the change to an unnatural white colour of the body). According to this it would appear to be merely superficial discolorations of the skin that writers understood by λεῦκαι,—a view that _Rayer_[70] seems to coincide with. _Pollux_ on the other hand offers an explanation as follows: ἀλφὸς μέλας, ἐπιδρομὴ σκιώδης, ἐπιπόλαιος, εὐίατος, ἀλφὸς λευκὸς, λευκότης ἐπιτρέχουσα τῇ ἐπιδερματίδι, αὐχμηρὰ, δυσίατος· _λεύκη_, ὅταν ἐπιτείνῃ ἡ λευκότης, καὶ φύσῃ τρίχωσιν λευκήν, εἰ δὲ κεντήσειας, ὕφαιμος, δυσίατος, ἐστιν ὅτε ὑπέρυθρος· _ἐπανθεῖ δὲ_ αὐτὸ (?) τοῖς _χείλεσιν, οἷον ἁλὸς ἄχνη_. (Black ἀλφός, a dark-coloured spreading eruption, superficial and easily curable; white alphos, a whiteness running over the epidermis (of the prepuce), dry harsh and difficult to cure; λεύκη, when the whiteness extends, and produces a growth of white hairs, and if you prick it, it is suffused with blood, difficult to cure, also sometimes reddish in hue. And the eruption comes out on the lips _like sea-foam_). Here λεύκη is evidently a much more deeply penetrating malady, as indeed it is described by _Celsus_[71] and _Galen_.[72] It corresponds with the white Leprosy of Moses. But the most curious thing is the statement appended to the effect that the affection broke out on the lips like sea-foam. This is certainly to be referred to some other form of λεύκη, unless indeed we are to take it in connection with the succeeding words in the text, λειχὴν ἄγριος (malignant tetter), in which case, as we have seen with regard to Mentagra (Tetter of the chin), the remark is based on a perfectly sound observation; and besides, the αὐτὸ gives absolutely no sense. On the other hand if Pollux’ datum in reference to the seat of λεύκη is correct, it must obviously afford much light for clearing up the meaning of the passage in Hippocrates, and in deference to it we shall be bound to read φοινικίη instead of φθινικὴ,[73]—an emendation that presents no difficulty, since φθινικὴ might very easily be read for φοινικίη, and indeed (as pointed out in the Note) was actually so read.