riAP. fjM 



62 BLINDNESS IN ANIMALS. [chap. 



sound. Where this animal is abundant, it may be heard 

 at all times of the day, and sometimes directly beneath one's 

 feet. When kept in a room, the tucutucos move both slowly 

 and clumsily, which appears owing to the outward action 

 of their hind legs ; and they are quite incapable, from the 

 socket of the thigh-bone not having a certain ligament, of 

 jumping even the smallest vertical height. They are very 

 stupid in making any attempt to escape ; when angry or 

 frightened they uttered the tucu-tuco. Of those I kept 

 alive, several, even the first day, became quite tame, not 

 attempting to bite or to run away ; others were a little 

 wilder. 



The man who caught them asserted that very many are 

 invariably found blind. A specimen which I preserved irj 

 spirits was in this state ; Mr. Reid considers it to be the 

 effect of inflammation in the nictitating membrane. When 

 the animal was alive I placed my finger within half an inch 

 of its head, and not the slightest notice was taken : it made 

 its way, however, about the room nearly as well as the; 

 others. Considering the strictly subterranean habits of the 

 tucutuco, the blindness, though so common, cannot be a 

 very serious evil ; yet it appears strange that any animal 

 should possess an organ frequently subject to be injured. 

 Lamarck would have been delighted with this fact, had he 

 known it, when speculating* (probably with more truth 

 than usual with him) on the gra.dua.Uy-acgutred blindness 

 of the Aspalax, a Gnawer living under ground, and of the 

 Proteus, a reptile living in dark caverns filled with water ; 

 in both of which animals the eye is in an almost rudimentary 

 state, and is covered by a tendinous membrane and skin. 

 In the common mole the eye is extraordinarily small but 

 perfect, though many anatomists doubt whether it is con- 

 nected with the true optic nerve ; its vision must certainly 

 be imperfect, though probably useful to the animal when it 

 leaves its burrow. In the tucutuco, which I believe never 

 comes to the surface of the ground, the eye is rather 

 larger, but often rendered blind and useless, though without 

 apparently causing any inconvenience to the animal : no 

 doubt Lamarck would have said that the tucutuco is now 

 passing into the state of the Aspalax and Proteus. 



instead of three or four times, and is more distinct and sonorous: when 

 heard from a distance it so closely resembles the sound made in cutting 

 down a small tree with an axe, that I have sometimes remained in doubt 

 concerning- it. 



* " Philosoph. Zoolog.," torn, i., p. 242. 



