248 THE SENSE-ORGANS AND PERCEPTION OF FISHES. 



tlie dark. Taken in connexion with the fact that tkis liabit of 

 whiting is supposed to occur in fine weather, it is possible that the 

 fish are guided by the phosphorescence either of the bait itself or of 

 the animals carried past it by the tide. Mention should also be made 

 of the fact that trout are often taken with a worm at night. 



Touch. — Of the fishes which seek their food by sight some are pro- 

 vided with barbels^ as the pouting and the cod, while a few have 

 special tactile organs, as the gurnards, and again the pouting. When 

 the pouting is hungry it takes its food promptly, without hesitation, 

 but when it has had about enough it frequently erects the barbel so 

 that it projects forward and touches the food with it, probably thus 

 tasting it. In the Brighton Aquarium I saw that the pelvic fins of 

 the pouting are used just as those of the rockling are, the fish 

 swimming with them set at right angles to the body and touching 

 the ground, but those at Plymouth were not seen to do this. The 

 latter are much smaller specimens, which fact may possibly account 

 for this difference in habit. 



The fingers of the pectoral fin of the gurnards are certainly used 

 in the search for food. Although the gurnards have good sight 

 and will swim up to a bait, they are chiefly bottom-feeders, and 

 move about with these fingers, half walking and half swimming as 

 they seek their food. On touching a worm with the fingers they 

 stop and scratch it about for some moments, as though raking it out 

 of the sand, and then suddenly turn and snap it up. Though the 

 fingers are thus employed, the gurnards often take food off the bottom 

 without touching it with the fingers. I did not succeed in seeing 

 the gurnards feed by night, but it is quite possible that they may 

 do so. 



I was surprised to find that the pogge [Agonns cataphractus) did not 

 appear to use the filamentous villi of the lower side of the head for 

 finding food. These villi are developed to a great degree, and bear 

 sense-organs which suggest that they may be used for this purpose ; 

 but though repeatedly watched, it was never seen to seek food other- 

 wise than by sight. Thinking that these structures might be of use 

 to it in discovering food buried in the sand, I made some trials, but 

 the fish never seemed to recognise the presence of the buried food. 



General Sensation- — The power which fishes possess of avoiding 

 obstacles even when deprived of sight is very remarkable. For ex- 

 ample, a bream in which the cornea has been rendered opaque, after 

 recovery from the shock does not run into the sides of the tank, but 

 swims round in a circle avoiding them. If a large obstacle, such as 

 a glass plate, is put in the way, the fish avoids that also. But it 

 would seem that this is because such an object cannot be brought 

 into position without causing a disturbance in the water which the 



