SENSES OF BATRACH1ANS. 1 3 



when the temperature permits of their activity. Serpents, Lizards, 

 Tortoises, Frogs, are all subjected to this law of their being. Some 

 hybernate upon the earth, under heaps of stone, or in holes ; others 

 in mud at the bottom of ponds. The senses are very slightly 

 developed in these animals ; those of touch, taste, and smell, being 

 very imperfect ; hearing scarcely so much so ; but not so with sight, for 

 their large eyes are provided with contractile eyeballs, which enables 

 certain reptiles — such, for instance, as the geckos — to distinguish 

 objects in the dark. Most Reptiles and Batrachians are almost 

 devoid of voice ; Serpents, however, utter a sharp hissing sound, and 

 Crocodiles howl; again, Geckos are particularly noisy, and Frogs 

 possess the well-known croak. Reptiles and Batrachians can, it is 

 true, be tamed ; but although they seem to know individuals, they 

 do not appear susceptible of affection ; this may be attributed to the 

 slight compass of their brain, as also that insensibility to pain which 

 enables them to support mutilations that would prove immediately 

 fatal to other animals. For instance, the Common Lizard frequently 

 breaks its tail in its abrupt movements. Nor does this curtailment 

 affect him ; for complaisant Nature renews its growth as often as it be- 

 comes necessary. In the Crocodiles and Monitor Lizards, however, a 

 mutilated part is not renewed, and the renovated tails of other Lizards 

 do not develop bone. In some instances, the eyes may be put out, 

 or the animal otherwise seriously injured. In the course of time, 

 without the animal having ceased to perform any of its functions, 

 they will be renewed. A Tortoise will continue to live and walk for 

 six months after it is deprived of its brain ; and a Salamander has 

 been seen in a very satisfactory state, although its head was, so to 

 speak, isolated from the trunk by a ligature tied tightly round 

 its neck. There is another curious peculiarity in the history of 

 Reptiles and Batrachians : each year, as they awake from their state 

 of torpor, they slough their old covering, or in other words cast 

 their skin. Their growth is slow, and continues almost through the 

 whole duration of their existence ; they are, moreover, endowed with 

 remarkable longevity. This is not very astonishing, if we consider 

 that (at least in our latitudes) they remain torpid for several months 

 yearly ; thus using up less of the materials of life, and, consequently, 

 ought to attain a more advanced age. The activity of organisation 

 in Reptiles and Batrachians is so slight that their stomachs feel less 

 of the exigencies of hunger ; hence they rarely take nourishment, 

 and digest their food very slowly. With the exception of the Land 

 Tortoises, whose regimen is herbivorous, most reptiles feed on living 

 prey. Some, such as Lizards, Frogs, and Toads, subsist on worms, 



