An impression prevails in some intelligent quarters that the bark of trees never becomes indurated, or "hide-bound," in technical language, unless something is wrong with the roots. It often does result from root injury; but there are many causes, quite independent of this. Nature herself provides for the rupture of bark in the formation of suber cells. It is by their action that "rifts "take place. Every kind of tree has its own species of suber cells engaged in this work, and hence the rifts in no two species are exactly alike. The effect of these growths has been checked in"hide-bound" trees, though often every other part of the tree is in a normal and healthy condition. In these cases the knife aids very acceptably in slitting such bark, the work the suber cells failed to perform.