98 



BLIND VERTEBRATES AND THEIR EYES. 



Tellkampf has remarked: 



The blind fish is found solitary and is very difficult to be caught, since it requires the greatest 

 caution to bring the net beneath them without driving them away. At the slightest motion of the 

 water they dart off a short distance and usually stop. * * * During my stay at Mammoth 

 Cave I observed that the Amblyopsis * * * remained motionless while I moved a burning lamp 

 around them, but they were disturbed by a slight motion of the water, proving that the light 

 made no impression upon their optic nerve, while their sense of touch was acute. 



Fig. 33. (a, b, c) Distribution of Tactile Ridges in Troglichthys. Side view of entire fish, dorsal and ventral views of head. 

 (d t e,f) Distribution of Tactile Ridges in Cliologasler papilliferus. Side view of entire lish, dorsal and ventral 

 views of anterior part of body. 



Dr. John Sloan in Packard, 1887, wrote: 



We carried our lighted candles within a few inches of them when near the surface, but they 

 seemed wholly insensible to their existence ; but if a drop of tallow fell in the water near them , 

 they would swim rapidly away. I brought home 12, as many as could live in my bucket. Of these 

 12 caught in September none died until next June, when the water became warmed to near 70°, 

 when several of them died with tetanic convulsions ( ?). I put the remainder in my cellar, where the 

 temperature ranged from 45° to 6o°, where one, "Blind Tom," lived 11 months, making 20 months 

 of existence without having taken any visible food. While in my aquarium they manifested total 

 indifference to light and sound. * * * They manifest great sensibility on the back and sides to 

 any approaching body, but do not notice an attack from below. It is not possible to capture one 

 by a side sweep of the net, but by passing it under him a considerable distance below and bringing 

 it up slowly there is no difficulty in taking them. In their native pools and in the aquarium when 

 disturbed they do not strike the bottom or sides of their surroundings, but seem to have a sense of 

 resistance (if the term is pardonable) which protects them. 



Miss Hoppin in Garman remarked : 



I am very sure they [cray-fishes], as well as the white-fish [Troglichthys'] have the tactile sense 

 developed in an unusual degree. At the least touch upon the water they dart away. * * * Nu- 

 merous tests convince me that it is through the sense of touch, and not through hearing, that 

 the fish is disturbed. * * * If I strike the vessel so that the water is set in motion, he darts 

 away from that side through the mass of water, instead of around in his usual way. If I stir 

 the water or touch the fish, no matter how lightly, his actions are the same. 



