[From the Foreign Scientific Journals]. 
Professor Meisner, of Basle, has recently given some account of the pro¬ 
digious growth of incisor teeth, in some of the Rodentia , which he thus accounts 
for. These teeth, in their normal state, are continually growing in length, slowly 
rising in height from the alveola, in such proportions as become requisite to com¬ 
pensate for the daily wearing away of their chisel-formed edges. This growth 
not ceasing during life, he remarks that all such teeth are invariably tubular at 
their base ; and that the same effect is produced not only in the incisor teeth, but 
in all others whose roots remain unclosed. In animals—such as the Elephant, 
Babiroussa, Hippopotamus, and Narwal,—where these bony productions serve as 
a defence, the same observation seems fully to apply; and they sometimes attain 
an enormous length, no given measure having been ascribed to them for the full 
period of their maturity, that depending solely upon the duration of the animal’s 
life. In the molar teeth of Hares, Rabbits, the Beaver, and some other Rodents, 
this fact holds equally good; but it is not so in the domestic Rat, Mouse, and 
others, in which the alveola is always closed ; he cites the observations of Blumen- 
bach on the monstrous growth of the molar teeth of a Hare, examined by him, 
and also those of Rudolphi on a similar lusus in an Indian Pig. We have fully 
confirmed these observations by an examination of several extraordinary examples 
of this phenomenon in the matchless Museum of the College of Surgeons. In a 
Rabbit, we observed the incisor teeth to have grown in a spiral form: in a Hare, 
also, in which, from their position, they must have occasioned the animal’s death, 
by entering the head, or pressing so firmly upon it, at either side, as to wound 
the flesh and penetrate it. It thus appears clear that a beautiful provision of 
Nature is exhibited in the formation of these teeth; their continual increase ena¬ 
bles them to preserve a fine, even, cutting edge, always set to a particular angle 
with each other, so long as they remain truly in opposition; the motion of gnaw¬ 
ing or cutting their food, having also the effect of keeping the teeth sharp, by 
means of their constantly slipping over each other. If, however, by any accident 
or malformation of parts, these teeth cease to act against each other, their growth 
still going on, they form a curved line, extending to an indefinite length during 
the animal’s life, and occasioning no doubt, in many instances, premature disease 
and death. So perfect is Nature in all her mechanism, that the slightest deviation 
from it, by accident or other causes, produces fatal effects. 
