SENSES OF BATRACAHIANS. 13 
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 tne 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, 
