THE TACTILE ORGANS. 99 



Blatchley states: 



* * * the least movement of the water frightened them, and they darted rapidly away, usually 

 at right angles to the course they were pursuing. The sense of touch, rather than that of hearing, 

 is, in my opinion, the one which has been intensified by long residence in the dark and silent recesses 

 of the caves. 



I have not found the slightest difficulty in capturing Amblyopsis with a small 

 dip net, either from a boat or while wading through the subterranean stream, and 

 I have caught one in the hollow of my hand. At such a time any amount of noise 

 I was capable of making did not affect the fishes found swimming in the water. 

 Frequently they were taken in the dip net without apparently taking any note 

 of the vibrations produced in the water until they were lifted out of it ; very rarely 

 a fish became noticeably scared. Such a one would dart off a few feet or a few 

 inches and remain on the qni rive. If not pursued, it soon swam off quietly; if 

 pursued, it not infrequently escaped by rapidly darting this way and that; when 

 jumping out of the water, often an abrupt turn in the opposite direction from which 

 it started would land it in the net, showing that their sense of direction was not 

 very acute. At other times, if disturbed by the waves produced by wading, one 

 or another individual would follow a ledge of rock to the bottom of the stream, 

 where it would hide in a crevice. But very frequently, much more frequently 

 than not, no attention was paid either to the commotion produced by the wading 

 or by the boat and dip net. In general it may be said that the fishes in their natural 

 habitat are oblivious to disturbances of the water until frightened by some very 

 unusual jar or motion, probably a touch with the net, when they become tensely 

 alert. The fact that they are not easily frightened suggests the absence of many 

 enemies, while their frantic behavior if once scared gives evidence that occasional 

 enemies are present and that they are very dangerous, or that the transmission of 

 the instinct of fear is as tenacious as the transmission of physical characters. 



Contrary to Sloan's observation, that they detect the presence of a solid sub- 

 stance in their path, I have never noticed that the fishes in confinement became 

 aware of the proximity of the walls of the aquarium when swimming toward them. 

 Instead, they constantly use the padded, projecting lower jaw as bumpers. Even 

 an extremely rapid dart through the water seems to be stopped by the projecting 

 jaw without serious inconvenience. 



Sticks, straws, etc. are never avoided by the fishes, even when the fishes had 

 not been disturbed for hours. By this I mean that they are never seen to avoid 

 such an object when it is in their path. They swim against it and then turn. An 

 object falling through the water does not disturb them even if it falls on them. 

 Gently moving a pencil in front of them does not disturb them much, but if the 

 pencil is held firmly in the hand it is always perceived and the fish comes to a 

 dead halt half an inch before it comes in contact with it. On the other hand, they 

 may be touched on the back or tail before they start away. They glide by each 

 other, leisurely and dignified, and if they collide, as they sometimes do, they 

 usually display no more emotion than when they run against a stick. But this in- 

 difference is not always displayed, as was noted under the head of breeding habits. 



A number kept in an aquarium having a median partition in which there was 

 a small opening were readily able to perceive the opening, swimming directly for 

 it when opposite it. This observation is in direct contrast to their inability to 

 perceive solid substances in their path. A sharp tap on the sides of an aquarium 



