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THE ZOOLOGIST
No. 689.—November, 1898.
BIOLOGICAL SUGGESTIONS.
ASSIMILATIVE COLOURATION.
By W.L. Distant.
(Continued from p. 409.)
Part II.
Fish appear to vary in colour and in an assimilative manner to the hue of the water in which they are confined.[1] According to Frank Buckland, "this is the case particularly with Minnows, Sticklebats, and Trout. Mr. Grove, the fishmonger at Charing Cross, will tell you where a Trout comes from by its colour. The Trout which live in peat-coloured water are sometimes nearly black; those from fine running streams, such as the clear chalk
- ↑ The action of the environment on fishes does not appear to be confined to colour alone, According to Prof. Seeley, "there are local races of many fishes which, under the changed conditions of physical geography, which from time to time affect the distribution of life on the earth, have become isolated from the rest of the race, so as to live on table-lands or low plains, in cold mountain lakes or in shallow swamps, in sluggish waters or rapid torrents, and thus, differently circumstanced, have developed into varieties distinguished by size, form, colour, and certain internal and external differences in the organs and proportions of the body" ('The Fresh-water Fishes of Europe,' p. 3). Leuciscus muticellus has all the fins "transparent and unspotted in Austrian specimens, but in examples from the Neckar the fins of the lower part of the body are yellow at the base, and this colour is occasionally seen in the dorsal and caudal. Bavarian fish have much black pigment in spots on the dorsal and caudal fins" (ibid. p. 173).
Zool. 4th ser. vol. II., November, 1898.
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