EXPLANATION OF THE PLATES. 
PLATE THE FIRST. 
ANATOMY OF THE STEM. 
Fig. 1. Platanus orientalis, Salicine. A transverse 
section of a young branch, to exhibit the organization, 
which is similar to that of the greater part of dicotyledon 
trees. 
Fig. 2. A magnified representation of a portion cut out 
of the above section. 
ato b. Bark. 
atoc. Outer part of the bark, dry and disorganized. 
b toc. The live part of the bark. 
cto d. A part of the bark which is continually pushed 
to the circumference. 
btod. Inner part of the bark, called the /iber or bast. 
e. The origin of the medullary radii that fill up the in- 
terstices of the wood, and which are formed of the cellular 
tissue of the bark. — 
f. The extremity of the filaments that form the inter- 
stices of the wood. 
btoi. The woody mass, composed of three zones, or 
layers, b—g, g—h, and h—7, 
htoi. The oldest of the three layers. 
toh. The second layer. 
btog. The third or youngest layer. 
b, g, and h. Zones which show the periods when the ve- 
getation slackened. 
ito k. Pith. 
Fig. 3. Ptychosperma gracilis. Palme. Vertical and 
transverse section of the stem, to show the difference be- 
tween the stems of monocotyledon plants and those of di- 
cotyledon plants. 
Fig.4. A magnified figure of the same. 
ato l. That part of the stem where the hardest woody 
fibres are the most closely collected together. 
