THE BREATHING APPARATUS, ETC., OF FISH 27 
hooked. That headlong flight of the trout implies no bodily 
pain ; but if the fish had previously been hooked, the resist- 
ance offered by the rod and line would cause the said flight to 
assume the appearance of a series of struggles, as if the creature 
were in physical agony. My own belief is that the suffering 
caused by capture with hook and line is not one whit more 
severe than that effected with the net ; but, after all, it must be 
left to physiologists to estimate the acuteness of sensation in 
cold-blooded animals, lowest in the vertebrate scale. This much 
is certain : that, as a rule, fish are quickly sensible of anything 
touching the skin, This is important to their protection from 
the attack by predaceous species, to which most of them at some 
or all periods of their lives are constantly exposed. 
In some species special organs of touch have been de- 
veloped, such as the barbules which depend from the lips of 
the carp, the barbel, the loach, the sturgeon, and many 
others, These appendages are exceedingly sensitive, and are 
used by these fish as feelers, in pursuit of food. In man, the 
extremities of the anterior limbs have become specialised as 
organs of touch; but the homologues of these limbs in fish 
—the pectoral fins—do not generally seem adapted for this 
function, although in the gurnards some of the rays, sepa- 
rated from the fin and well supplied with nerves, suggest 
the office of fingers or feelers. 
The visual powers of fish offer a subject of much interest, 
not only to the angler, whose purpose it is at once to excite 
The sense and delude them, but to every observer of nature, 
ofsight because the sense of sight is that which appears 
to have received in fishes a higher development than any 
other. The first peculiarity apparent in a fish’s organ of 
sight is the total absence of a true eyelid. Some marine and 
exotic species, indeed, as well as the British shad, can extend 
a fold of skin over the eyeball from the posterior and anterior 
parts of the orbit, leaving a vertical transparent slit over 
the pupil; but, with this exception, none of the fish of our 
