THE COLORATION OF FISHES. 337 
same action oi sunlight. ‘The case of Trout (Salmo fario, Linn.) 
kept in a white basin losing their colouring, and approximating to 
the no-colour of the dish, is well known, and has been experimented 
upon by many since Stoddart proved it as a fact on Tweedside. 
Minnow (Leuciscus phoxinus (Linn.)) are frequently kept in this 
way by anglers, in order to brighten and clear them before using 
them asa bait. Fishermen are also well acquainted with the fact 
that flat-fish especially vary with the ground from which they are 
taken, and this may either be from the direct action of light or 
from sympathy. I use this term indefinitely, not with the inten- 
tion of begging the question as to its mental, physical, or other 
cause. I have noticed such changes more rapidly and definitely 
in lower forms, or at least higher forms of a lower class, such as the 
Cephalopods. As these are intelligent and predatory, they may 
produce these changes by the sentiments of passion or fear, so that 
we must yet be careful not to jump to conclusions in regard to 
their changes resulting from the “sympathy” in question. There 
are, however, certain fishes amongst which individuals may be 
quoted as taking particular colouring under special and marked 
surroundings. Thus young Cod (Gadus morhua, Linn.) of a given 
development, caught towards the tangle zone, and commonly named 
Rock-cod, are markedly more brilliant in colouring than their 
fully-developed congeners, living in the deeper waters, and 
frequenting the bottom. Where cod can locally find nourishment 
in similar localities up to the full size, they retain the same 
colouring to a great extent, and almost look like a different species. 
Indeed, according to an admirable worker in this direction— 
Captain Dannevig, a Norwegian—the two classes of cod are very 
notable off the coast of Norway. Further, he finds that their 
colouring is distinct, even from the earliest stage, the ova of the 
one showing markedly tinted compared with the colourless 
globules of the other. This he has himself shown me. I do not 
believe this distinction, however, to be even varietal, but indi- 
vidual, and showing that the prevailing tint acquired is less _ 
evanescent than might have been anticipated. On the other 
hand, as all the frequenters of the same zone are more richly 
toned, the colouring may come in all reasonable likelihood from 
the food, and tint the growing ova along with the creature itself. 
We may reach a further step in this inquiry by examining the 
