10 TOPOGRAPHY OF CHLOROPHYLL APPARATUS IN DESERT PLANTS. 
stant relation was not learned. Ina branch 1.6 cm. in diameter, as well 
as one 1 cm. in diameter, the chlorophyll was confined to the cortex. 
The following measurements were made: 
Distance Fi 7 Depth of Width of 
‘ Diameter Width of Depth of Width of ‘ 
ote. of stem. cortex. Strellodenns phelloderm. ca entropy. u 
em. mm. Bb fad Bb & led 
6 Zi, oacasger i esas |) eadatges 78 41.6 
21 355 B20: +e weeieatel |) uehtine 96 25.6 
34 4 300 54-4 39.2 89.6 28.8 
49 4-5 415 80 22.4 102.4 22.4 
64 6 547-8 80 32 102 32 
79 8 547.8 76.8 19.2 96 35-2 
144 10 581 80 28 108.8 25.6 
178 16 1079 118.4 28.8 147-2 32 
CONDALIA SPATHULACA. (Plate 2,4, and fig. 4.) 
The plant from which the branch studied was taken is growing by the 
Hospital Road near the northeast corner of the Laboratory domain. The 
shrub is about 1.5 m. high and is a very vigorous one. 
Sections were made at the fol- 
lowing distances from the tip: 
2,5, 20, 35, 65, 95cm. These 
were 1.5, 2, 4,7.5 mm. and 1.2, 
1.7 cm. in diameter, respec- 
tively. 
A cross-section of a young 
branch 1.5 mm. in diameter and 
2 cm. from the tip shows the 
following leading structural 
characters: An epidermis witha 
thin cuticle bounds the stem. 
« Within this is a hypodermal por- 
tion three cells thick, and within 
; ; . this, again, is a collenchyma-like 
Fic. 4.—Condalia spathulaca: Section from : j 
a branch 2 mm. in diameter. tissue about as_ thick. The 
chlorophyll band, about three 
cells wide, lies immediately within the last-mentioned tissue and occupies 
the central portion of the cortex. A relatively narrow inner cortical portion 
separates the chlorophyll band from the cambium. This inner part consists 
of a discontinuous hard-bast ring and thin-walled parenchyma. The former 
abuts on the chlorenchyma. The wood and the pith present no character- 
istics of interest in the present connection. In addition to the chlorophyll 
band, chlorophyll occurs also in most of the inner cortical parenchyma, in 
the medullary rays of the wood, and in the outer pith-cells. 
NO a are ae 
ae. 
wees see 
