DESCRIPTION OF PLATES. 171 
For fuller information regarding pollen, the 
student is referred to the Micrographic Dic- 
tionary. 
EPIDERMIS OF PLants. (PuatTe VIII.) 
The higher plants are invested with a mem- 
brane made up of a mosaic of more or less flat- 
tened cells, which is called the epidermis. In 
many plants this may be peeled off from the 
green twigs or from the surface of the leaves. 
The examination of such a specimen under the 
microscope is interesting not only on account of 
the beauty and variety of patterns exhibited in 
this natural mosaic, but also as a lesson in vege- 
table histology. 
The cells of the epidermis are usually color- 
less, and being joined by their margins in a single 
plane, no preparation is required except to place 
a fragment of proper size in water or glycerine 
under a thin glass cover. They are readily seen 
with a low-power objective,— one inch or one- 
half inch,—and usually a flattened nucleus, con- 
taining a nucleolus, may be seen attached to one 
portion of the cell wall. 
Detached cells from the parenchyma of the 
leaf containing a quantity of green granules 
(chlorophyl) are sometimes seen adhering to 
the fragment of epidermis which has been stripped 
from a succulent leaf or green twig. 
Plate VIII Figs. 1, 2, 8, and 4, will serve to 
give an idea of the variety of patterns resulting 
