_ 
58 ELEMENTS OF PLANT ANATOMY. 
the grains are larger and form a crust, as in the covering of the 
bay berry. Lastly, the glazing consists of a homogeneous coating 
which covers the cuticle as a continuous membrane ; an example 
of this is found in the leaves of the Sempervivum tectorum, of 
Texas, and in the stems of Opuntia. 
Organs provided with wax coatings do not become wet when 
put into water for a short time. As this is also true to some 
extent of organs whose epidermis is simply cutinized, it is con- 
cluded that all cutin contains a slight quantity of wax. Other 
substances of a different chemical nature from wax occur on 
the epidermis of some plants; such are the gold and silver coat- 
ings of certain ferns. 
THE COMPOUND EPIDERMIS. 
This consists of several layers of cells. They all originate, 
however, from the dermatogen which divides by walls running 
ey 
FIG. 28. 
A cross-section through Begonia leaf. E' compound epidermis. P palisade tissue. S spongy 
tissue. B cross-section through leaf of Tradescantia discolor. E lower epidermis with 
stoma, s. Ko upper epidermis, both simple. W water tissue formed from hypoderma. 
x 150. — (decd. to Pfitzer.) 
parallel with the surface of the organ. In this way is formed 
a dermatogen of several layers which produces the compound 
