Stomata in Halophytes. 
5or 
TABLE XII 
Distribution and Size of Stomata taken from Different Regions of 
Salicornia annua. 
No. of In- 
ternode. 
No. of Stomata 
per sq. cm. 
Condition of 
Stomata. 
Mean Diameter of 
both Guard Cells. 
Diameter 
of Rift. 
Diameter 
of Pore. 
I 
10,500 
Widely open 
40^ 
20 n 
20 /X 
II 
9 , 75 ° 
Half shut 
22 „ 
10 „ 
4 », 
IV 
11,875 
Half shut 
26 „ 
5 „ 
VI 
23,125 
Widely open 
22 ,, 
— 
2 „ 
VIII 
23.625 
Widely open 
16 „ 
— 
2 >, 
IX 
18,750 
Unopened 
— 
— 
In internodes VI and VIII the stomata were fully formed and open, 
but the epidermal cells were much smaller than on lower internodes, and 
probably neither these nor the guard cells had reached their full size. In 
internode IX the epidermal cells were in a state of active cell-division — the 
stoma mother-cells were in some cases just cut off ; in others they had 
Fig. 11. Outline of stomata taken from the lowest and two uppermost internodes 
respectively of a shoot of Salicornia ; drawn to scale and x 500. 
just divided to form the guard cells, but in no case had any aperture been 
formed. It is of some interest to note that the guard cells in the upper and 
younger internodes open long before the stomata reach their full size. 
Typical stomata are shown drawn to scale in outline only in Fig. 11. 
Some observations were made as to the effects of light and darkness 
on the stomata of Salicornia annua and X. ramosissima . From experi- 
ments made on July 14, 1909, it was found that stomata, previously half 
open, closed within three hours when placed in a dark room at nearly the 
same temperature and relative humidity. In this condition the pore 
appeared completely closed, but the rift was in every case still visible ; 
within ten minutes all the stomata began to open, presumably owing to 
the illumination of the microscope stage. Measurements were made of the 
stomata in the open and closed condition, and from these and from the 
outlines shown in Figs. 12 and 13, it appeared that guard cells expand 
L 1 
