Of its close resemblance to the Kuan ware there can be no doubt, for two highly reputable Chinese writers[137] describe the two wares simultaneously and under one heading, enumerating their various colours in order of merit as _fên ch´ing_, _tan pai_, and _hui sê_ (see p. 60), besides mentioning the several kinds of crackle which appeared in the glaze. The only distinctions which the author of the _Ch´ing pi ts´ang_ draws between the two wares are that (1) the Kuan yao crackle is of the "crab's claw"[138] type, while that of the Ko is like fish-roe,[139] and (2) the Ko glaze is somewhat less beautiful than the Kuan. With regard to the crackle, other writers assert that short cracks are characteristic of the Ko yao, and one author uses the picturesque phrase, "crackle of a hundred dangers."[140] Accidental splashes of contrasting colour, which sometimes assumed fantastic forms, were common to the Ko and Kuan wares, as mentioned on p. 65, and the author of the _Po wu yao lan_ explains these as "originating in the colour of the glaze and forming on its outer surface," and as "due to the fire's magic transmutation." Another account of the ware given in the _Ko ku yao lun_ depicts it as of deep or pale _ch´ing_ colour, with brown mouth and iron foot, and adds that when the colour was good it was classed with Tung[141] ware. The same passage further informs us that a great quantity of the ware "recently made at the end of the Yüan dynasty" was coarse and dry in body and inferior in colour, a statement to which we shall return presently. [Illustration: PLATE 19. Vase of close-grained, dark reddish brown stoneware with thick, smooth glaze, boldly crackled. Ko ware of the Sung dynasty. Height 10⅝ inches. _Eumorfopoulos Collection._ ] Other descriptive references to Ko yao include a verse on a Ko ink palette belonging to Ku Liu,[142] which was "green (_lü_) as the waves in spring"; the eighteenth-century list of Imperial wares[143] which mention "Ko glazes on an iron body," of two kinds, viz. millet-coloured and pale green[144] (or blue), both stated to have been copied from ancient specimens sent down from the palace; and a single specimen in Hsiang's Album, which is given as _fên ch´ing_. In these various descriptions it is possible to recognise a celadon green ware, green as the waves of spring, while the familiar stone grey and buff crackled wares, which range from greyish white to pale grey green and greenish yellow, seem to be indicated in the expressions _mi sê_, _fên ch´ing_, _tan pai_, and _hui sê_. The modern versions of the latter class, which are fairly common, are usually known even to-day as _Ko yao_, the expression in potter's language being practically synonymous with "crackled wares."[145] Other ancient factories where similar wares were made are Hsiang-hu and Chi Chou.[146]