116 
THE RAT. 
this fact. It is, they say, an incisor tooth of a rat, which, 
from the canse above mentioned, has increased its growth 
upwards to such a degree, that it has formed a complete 
circle and a segment of another ; the diameter of it, is about 
large enough to admit a good-sized thumb. 
To "Substantiate this point, the Quarterly Review " 
says, " We once saw a newly-killed rat to which this 
misfortune had occurred. The tooth, which was an upper 
one, had in this case also formed a complete circle, and the 
point, in winding round, had passed through the lip of the 
animal." 
However curious all this may appear, and pretty in 
theory, still, in taking a practical survey of the subject, it 
appears very much like a physical impossibility. We know 
well that there is no accounting for the freaks of 
nature, and should she provide a rat with but one incisor 
tooth instead of four, then might we easily imagine that, 
from its curved or circular formation, it would, in the event 
of its continuous growth, and the entire absence of all 
obstructions, become a perfect ring, or rather a kind of 
diminishing circle. But for a rat, either by force or acci- 
dent, to lose an upper tooth, and then for the corresponding 
one in the lower jaw to grow out of the mouth, and wind 
its way round till it passes into the skull, or for an 
upper tooth to grow through the under-lip till it forms 
a complete circle, seems to us not only mysterious but 
paradoxical ; because, from the close proximity of the teeth 
in either jaw, and their flexibility, we cannot conceive how 
it is possible for a rat to gnaw a hole through our flooring, 
or through a brick wall, without the whole of the incisor 
teeth coming more or less in contact with the substance 
gnawed. 
Now, with all deference to these gentlemen, let us, for 
experiment's sake, break out an under incisor tooth of a rat, 
and then keep him on soft bread and milk for six months, to 
prevent the teeth being ground down by any hard sub- 
stance. What then might we expect ? Why, that the sound 
pair, coming in constant contact with each other in the course 
of eating, would, to a certain extent, irajDcde their growth ; 
while, at the same time, the odd one, having nothing to 
check its growth, would extend to, say a quarter of an inch. 
