88 Observations on the Natural History 
mander, the lateral movements of the trunk will be still more 
limited than in the proteus, by reason that the ridge, formed 
by the canal of the spinal cord, will impede the free motion of 
the articular processes on one another. We have observed at- 
tentively, continue the authors, and compared the movements 
and mode of progression of the proteus, and of the salamander 
and its larva, both in water and out of it ; and have had the 
satisfaction of seeing that these movements, as well in swimming 
as in walking, correspond with the consequences previously de- 
duced from a simple examination of the skeleton. A few of 
these observations they then proceed to relate. 
The protei which, with this view, they submitted to observa- 
tion, had already lived many months in earthen vessels, the 
bottoms of which were flat and of the figure of a parallelogram. 
To these vessels were adapted lids formed of many pieces ; but 
so fitted together that the light was unable to penetrate, and 
the animals consequently lived always in complete darkness. 
When it became necessary to change the water, a portion of 
the lid was removed, and then the animal, by moving to the 
opposite side of the vessel, was able to continue in obscurity. 
It has been already observed, that the proteus, in ordinary 
circumstances, remains as if immoveable at the bottom of the 
vessel ; but at once begins to move with more or less rapidity 
as the light is let in upon him. Of this fact, the authors availed 
themselves in their observations on the movements of these ani- 
mals. Having first discovered in what part of the vessel the 
animal reposed, the piece of lid above him was gently raised, so 
as to expose him to light. As soon as he felt its influence, he 
instantly began to move and withdraw himself to that part of 
the vessel which was still dark. In making this movement, 
however, he did not always employ the same kind of motion. 
Sometimes he drew up the lower part of the trunk and the tail, 
or rather gathered himself up in the manner of a serpent. In 
doing this, he made use only of the muscles of the spine, and 
not of those of the hind limbs, which, during this action, re- 
mained quite at ease, and followed the trunk as if they had been 
paralytic. When the body was thus gathered up, and formed 
into a serpentine line, the animal thrust the hind limbs to the 
bottom of the vessel ; then stretching forward the whole trunk, 
