M. Mirbel indeed, though he admits the importance of this part in the several ways above mentioned, contends that it is not a distinct organ like the cuticle of animals, but merely formed of the cellular parts of the plant dilated and multiplied, and changed by their new situation. This is very true; but upon the same principle the human cuticle can scarcely be called a distinct organ. Its texture is continually scaling off externally, and it is supplied with new layers from within. Just so does the cuticle of the Birch peel off in scales, separable, almost without end, into smaller ones.
Examples of different kinds of cuticle may be seen in the following plants.
On the Currant tree it is smooth, and scales off in large entire flakes, both from the young branches and old stem. The same may be observed in the Elder.
The fruit of the Peach and the leaf of the Mullein have a cuticle covered with dense and rather harsh wool, such as is found on many Mexican plants, and on more Cretan ones. The latter we know grow in open places under a burning sun.
