OF THE CUTICLE OR EPIDER^nS. 53 



In grasses and some other plants the in,s^enious Mr. 

 Diivy has found a flinty substance in the cuticle. 



What seems to be the cuticle on the trunk of the 

 Plane, the Fir, and a kind of Willow called Salix triaii- 

 dra^ rather consists of scales of bark, which having per- 

 formed their functions and become dead matter, are re- 

 jected by the increasing bark beneath them ;(3) and this 

 accords with M. Mirbel's idea of the cuticle. The old 

 layers of bark in the Chestnut, Oak, and many other 

 trees, though not cast off, are of the same nature ; and 

 these under the microscope exhibit the same cellular 

 texture as the real cuticle. 



(3) [Hence the white appearance exhibited at certain seasons 

 of the year by the trunk and branches of the Button wood \vef 

 (Platanus occidentalis.)J 



