THE BLIND FISHES OF NORTH AMERICA. 483 



A number kept in an aquarium with a median partition, in 

 whicli there was a small opening, were readily able to perceive the 

 opening, swimming directly for it when opposite it. This observa- 

 tion is in direct contrast to their inability to perceive solid sub- 

 stances in their path. A sharp tap on the sides of an aquarium in 

 which six blind fishes were swimming, where they had been for a 

 number of days undisturbed, in a dark room, caused nearly all of 

 them to dart rapidly forward. A second tap produced a less unani- 

 mous reaction. This repeated on successive days always brought 

 responses from some of the inmates of the aquarium. Those re- 

 sponding were not necessarily the nearest to the center of disturb- 

 ance, but sometimes at the opposite side of the aquarium or vari- 

 ously distributed through it. After a few days the fishes took no 

 notice of the tapping by any action observable in the artificially 

 lighted room. 



Such tapping on a well-lighted aquarium containing both Cholo- 

 gaster and Amblyopsis was always perceived by the Amblyopsis, 

 but the only response from these imperturbable philosophers was a 

 slight motion of the pectorals, a motion that suggested that their 

 balance had been disturbed and that the motion was a rebalancing. 

 Chologaster, on the other hand, invariably darted about in a fran- 

 tic manner. One individual of Amblyopsis floating on the water 

 was repeatedly pushed down by the finger without being disturbed. 

 If, however, they are touched on the side they always rapidly dart 

 away. 



From everything observed, it is quite evident that Amblyopsis 

 is not keener in perceiving objects or vibrations than other fishes, 

 and ordinarily pays much less attention to them. Whether it pos- 

 sesses a greater power of discrimination of vibrations it would be 

 difficult to say. It certainly possesses very elaborate tactile or- 

 gans about the head. These tactile organs are probably more serv- 

 iceable in detecting and precisely locating prey in the immediate 

 neighborhood than for anything else. Some observations on young 

 Amblyopsis are of interest in this connection. 



The young, with a large amount of yolk still attached, show a 

 well-developed sense of direction. A needle thrust into the water 

 near their heads and in front of them causes a quick reaction, the 

 young fishes turning and swimming in the opposite direction. They 

 will do this two or three times, then, becoming exhausted, will re- 

 main at rest. Sometimes an individual will not move until it is 

 actually touched by the needle. The needle must come within 

 about three or four millimetres of the fish before it is noticed. 

 Then, if it produces any result, it causes the fish to quickly turn and 

 swim some distance, when it falls to the bottom again and remains 



