PHARMACEUTICAL BOTANY 
36 
a.c. 
m , 
Histology of Growing Apex. —When the bases of the leaves of the 
current year, the circinate leaves of the following year and the large 
mass of brown scales have been removed from around the apical bud 
of a well-grown plant, the following structures may readily be ob¬ 
served with a hand lens: 
1. The apical cone (punctum vegetationis ), a rounded papilla, which 
occupies a terminal position in the apical region. 
2. The young fronds, arranged around the apical cone. 
Upon removing the extreme apex of the apical cone with a sharp 
razor, mounting in dilute glycerine or water and examining under 
low power, it will be noted 
that a large pyramidal cell 
occupies the center of the. 
apical cone. This is the 
apical cell (Fig. 14). The 
cells surrounding it have 
been derived by segmenta¬ 
tion (cell-division) from it, 
by means of walls parallel 
to its three sides; they are 
termed segment cells and in 
turn undergo further di¬ 
vision and redivision to 
originate the entire stem 
tissue and leaf tissue. Step 
by step the tissue cells become modified into epidermal, cortical, 
bundle and fundamental cells. 
Histology of Mature Root. —Transverse sections cut some dis¬ 
tance above the apex will present the following structures for 
examination: 
1. Epidermis, of epidermal cells whose outer walls are brown. 
Some of these cells have grown out as root hairs which surround soil 
particles and absorb water with mineral salts in solution. 
2. Cortex, of many layers of cortical parenchyma cells with brown 
walls. The outer layers of cells of this region are thin-walled, while 
the extreme inner ones are lignified and form a sclerenchymatous 
ring which surrounds the 
Fig. 14. —Apical cell of a fern rhizome in 
vertical longitudinal section. a.c., apical 
cell; h, hair; m, meristem. (After Hofmeister.) 
Sedgwick & Wilson's General Biology, 
Henry Holt & Co. 
