102 NATURE'S CAMOUFLAGE 



four bass, nice fish about 8 or 10 ounces each, of a 

 dark olive hue. They were put in a tin bath painted 

 white inside, and the net was shot again. Four more 

 bass were taken of the same size and colour as the first 

 lot, but on taking them to join the others in the bath 

 they did not look like fish of the same species. During 

 the twenty or thirty minutes that had elapsed since the 

 first lot were put into the bath, the effect of the white 

 lining of the bath had been to change their dark colour 

 into pale ashen grey, strangely in contrast with the 

 complexion of the newcomers. 



Anadromous fish — that is, fish migrating seasonally 

 from sea to river and from river to sea — are subject to 

 still more remarkable changes of colour to harmonise 

 with the difiference in environment. Evidently a silver 

 coat is protective in the sea. The salmon parr before 

 setting of for the salt water doffs the motley of a brown 

 trout, which has served it well among the dark stones 

 and shades of its natal stream, and puts on a jacket of 

 glittering silver, in which garb it is termed a smolt. 

 Conversely, when he returns to the river as a grilse or 

 spring salmon, still in the same shining attire, he will 

 not have been long in the fresh water before the 

 metallic lustre of his scales begins to tarnish, turning 

 to russet and dark grey, matching the furniture of his 

 new lodging. 



In former times, before the life history of the common 

 eel had been satisfactorily investigated, it was believed 

 that British waters were inhabited by two distinct 

 species, the brown eel and the silver eel. It has now 

 been ascertained beyond any doubt that these are fish 



