CONDALIA SPATHULACA. 11 
The chlorophyll band is a relatively narrow tissue which lies rather deeply 
in young stems, but in older ones much nearer the surface (see table 
of measurements below). The cells are either cuboid or slightly elongated. 
If the latter the long axis is tangential to the surface. 
With increase in diameter certain changes take place in the stem which 
are most marked in the cortex. Cork is formed in very small stems. In 
a stem 2 mm. in diameter and 5 cm. from the tip it was observed in the 
hypodermal cells, where a considerable amount of periderm was organized. 
This is more pronounced in branches 4 mm. and still more in those 7.5 mm. 
in diameter. The phelloderm, however, is not formed until the stem is 
somewhat older. In astem 1.2 cm. in diameter the phelloderm was about 
two cells in thickness and was chlorophyll-bearing; in a branch 1.7 cm. in 
diameter the amount of chlorophyll-bearing phelloderm was so great as to 
considerably increase the width of the chlorophyll tissues. The chlorophyll 
early leaves the wood and the pith; in a stem only 7.5 mm. in diameter it 
was confined to the outer portion of the cortex. 
The following measurements were made: 
; ; Width of | Depth of 
Diameter | Distance | Width of ! 
of branch.| from tip. | cortex. bande Band. 
mm. em Kb BK | Bb 
1.5 2 208 38.4 70 
2 5 256 32 80 
4 20 448.2 25.6 64 
735 35 1162 64 | 64 
12 65 1494 80 i 19.2 
17 95 1147 73-6 41.6 
COVILLEA TRIDENTATA. (Plate 1, B, and fig. 5.) 
The plant from which the branch studied was taken is growing near the 
road a few meters east of the Laboratory building. Sections were cut at 
the following distances from the tip: 5, 10, 20, 35, 65, 95 cm., and were 
1, 1.5, 3, 4.5, 7.5, 9.5 mm., respectively, in diameter. 
The young and angular stem, 1 mm. in diameter, has the following gen- 
eral relations of its tissues: Within the epidermis, which has a rather thin 
cuticle, lies the broad chlorophyll band, which is about three cells in thick- 
ness. A discontinuous hard-bast ring is placed immediately within the 
chlorophyll band. This is made up of larger and of smaller groups, of which 
the former lies opposite the angles of the stem. More or less stony tissue 
also is found in the same ring. Between the groups of mechanical tissue 
is thin-walled parenchyma. Within the hard-bast ring, and separating it 
from the cambium, are the distal ends of the medullary rays and paren- 
chyma between them. There is nothing noteworthy in the present connec- 
tion regarding either pith or wood. 
