272 How to obtain it. 
close their eyes, but that they rest their bodies is very certain. 
We know that they feel fatigue, and that they spend part of their 
time in holes or under shady banks. They love shade, in fact, 
and cannot do well without it. At night, when viewed by the 
light of a lantern, a whole pond full may be watched at times 
without their seeming to be in any way inconvenienced by the light. 
They are at such a time often found to be in a perfectly quiescent 
state, and also in the day-time I have seen a pond-full apparently 
sleeping. The great difference between their sleep and that of 
birds or animals is that they are apparently able to see at the same 
time. We know well enough that all parts of the body do not 
necessarily rest at once, and we also know that the sleep of a city 
merchant and of a savage are two very different things. The 
latter will almost sleep with his eyes open, and we can well under- 
stand a fish being on the alert, even though asleep in the sense of 
the body resting. 
The sense of taste and smell are to an extent existent in 
trout. The nostrils are well developed, but have no communica- 
tion with the mouth, nor are they used in any way for purposes 
of breathing. Probably under some circumstances the power of 
smell is useful to the fish in obtaining food, as for instance, in 
blind examples which I have met with that have otherwise been 
in excellent condition. The odour of water is naturally extremely 
varied, according to the different ingredients or pollutions which 
may exist in it. That trout are sensible of these variations there 
is no room for doubt. They themselves give off odours and so do 
other fishes, and I have long had reason for supposing that eels 
can smell trout and follow them by scent. An otter can certainly 
do so as I have found to my cost, and these animals on a stream 
must become sensible of the presence of an unusual number of 
fine trout kept in ponds near, the water from which is discharged 
into the stream. 
Trout possess in a degree the sense of taste, but it cannot be 
said to be at all well developed. They will accept some foods 
while they reject others equally.good or even better. This shows 
that there must be a distinguishing power between one article of 
food and another. Fish culturists know that when accustomed to 
certain kinds of food they often refuse an article with which they 
