ant od 5 Mes 
266 BOTANICAL GAZETTE. [ October, 
seem to be but developments of the cortex and epidermis. 
In the axils of these bracts occur whatever flowers or branches 
ears. 
e epidermis of the stem is rather rough, and is com- 
posed of irregularly shaped cells. The outer wall is often 
considerably cuticularized, frequently becoming half the 
thickness of the cell. Numerous processes, like very rudi- 
mentary trichomes, cover the epidermis, and in optical sec- 
tion give it the appearance of being covered with small 
nobs. The cortex (fig. 1, c.), is for the most part made up 
of palisade parenchyma, containing chlorophyll. This chloro- 
phyll-bearing parenchyma completely invests, the young 
shoots except at the nodes, where it is abruptly terminated. 
Within this part of the plant all the leaf work is done. As 
the stem increases in age the epidermis becomes more Ccutl- 
cularized, the wood tissues encroach more and more upon 
the cortex, and when from three to five years old its leaf work 
is over and the stem has lost all resemblance to the rush. 
Se ee ee 
eo in 2 HTL cp as Fy nlp om A 3 
, Arranged either in 
single or double verti- 
A Nr € eae in the epider- 
97] mis, and leading ito : 
{A the cortex, are found the 
stomata (fig. 2, 5, 5, 5; etcz).992 
The stomatic structure of 
rm 
four specially developed ep!- 
dermal cells (fig. 3). Below” 
this opening are placed the’ 
guard cells, two in num ely (3a 
and ovate triangular ina cen- 
tral section (fig. 4). By care: 
ful manipulation the uae? 
. cells may be seen to respon 
to the presence of water. | ‘ 
fig. 5 is shown a stoma wit 
guard cells wide apart. Fig. 
6 shows them partly closed, the ex 
ties of the cells being in contacts 
fig. 7 shows them still more nearly 
d closed. Indeed it is only after 4 lon 
soaking that the slit opening can be entirely closed. : 
8 
The stoma of Ephedra 
x 250 “! : 
