. Animal Life and the World of Nature; A magazine of Natural History. . fl. Drawing bij Miss Annie Willis. Fig. 1. LOWER SIDE OF A 1'IEBALD PLAICE. Showing the pigment developed after six mouths' exposure to light. A PIEBALD PLAICE. By J. T. Cunningham, , TT is well known that the plaice and other fishes of the family of Fiat-Fishes or -*- Pleuronectidse arc normally coloured on the upper side and white on the lower. The whiteness of the lower side is due to the absence of black and coloured pigments and the presence of a white substance in the skin. For convenience in description w
. Animal Life and the World of Nature; A magazine of Natural History. . fl. Drawing bij Miss Annie Willis. Fig. 1. LOWER SIDE OF A 1'IEBALD PLAICE. Showing the pigment developed after six mouths' exposure to light. A PIEBALD PLAICE. By J. T. Cunningham, , TT is well known that the plaice and other fishes of the family of Fiat-Fishes or -*- Pleuronectidse arc normally coloured on the upper side and white on the lower. The whiteness of the lower side is due to the absence of black and coloured pigments and the presence of a white substance in the skin. For convenience in description we may restrict the term " pigment" to the colouring-matters, excluding the white substance. Specimens - of plaice and other flat-fishes are, however, occasionally obtained which show more or less colour on the lower side, varying from small patches to complete pigmentation of the whole surface. Conversely, specimens also occur in which pigment is entirely absent from part or all of the upper side, the lower side being white as usual. The colourless area in such specimens is usually sharply defined, and there is no gradual transition from the coloured region to the uncoloured. The lower figure of the coloured plate represents a living piebald plaice which came into my possession at the Plymouth Laboratory a few years ago. It was caught by a seine-net in the Hamoaze, the estuary of the river Tamar, and was kept alive in the aquarium. The occurrence of such specimens seems at first to disprove completely the hypothesis that the absence of colour from the lower side in ordinary flat-fishes is due to ,the fact that no light falls upon that side. At the Plymouth Laboratory I carried on for some years experimsnts to ascertain whether pigment would be developed on the lower sides of flounders when those sides were exposed to the light. For this purpose the fish were 333. Please note that these images are extracted from scanned page images that may have been digitally enhanced
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherlondo, bookyear1902
