40 TOPOGRAPHY OF CHLOROPHYLL APPARATUS IN DESERT PLANTS. 
Measurements on the chlorophyll band. 
: Diameter |_,Width of | Depth of 
| me of brane. |°IgropPYH ehlorophy 
' mm, be & 
: ae ree 19.2 
[ aan 16 
355 25.6 96 
10 25.6 108.8 
1 Cereus Qiganteus..... cc eeeeereee|  veeeee | caer 581 
2 32 80 
i 12 8o 19.2 
‘ 3 64 48 
95 64 80 
an ee 498 
BO ll Saeniete 1162 
3-5 144 80 
8 112 64 
2 83.2 18.8 
2.15 60.8 32 
1.5 48 38.4 
11.5 160 64 
3 83 83 
11.5 130 144 
49 246 130 
8 144 64 
30 224 128 
1.6 32 48 
DO isisacsucsesens 9 160 32 
Zizyphus parryi.......... ane 3 57.6 19.2 
D0 wssscmarvinceineergacimpincese 14 64 41.6 
PERSISTENCE OF CHLOROPHYLL IN THE WOODY CYLINDER. 
Chlorophyll in the woody cylinder is a striking characteristic of young 
Parkinsonia and Prosopis branches especially, and is found in nearly all of 
the other desert perennials. Compared to the chlorophyll of the cortex, 
however, it is likely of little profit to the plant, for the reason that it 
disappears early from the stem. How long it persists was not learned in 
any case, since the plants studied did not exhibit annual rings, or in any 
other way give a clue as to the rapidity of growth. 
The subjoined table gives the character of the branch at a time when 
the chlorophyll for the most part had already left the woody cylinder. The 
measurements were made on the disappearance of chlorophyll. 
Species. Diameter 
Distance 
ot branch. | from tip. 
Remarks. 
Celtis pallida... 
Covillea tridentata............... 
Condallia spathulaca............ 7-5 
Keeberlinia spinosa........ 15 
Krameria canescens. 3.5 
Olneya tesota............5065 ‘ 2 
Parkinsonia microphylla........ 15 
torreyana.........-. 22.5 
No chlorophyll in wood or pith. 
Do. 
Do. 
Sparingly present in wood and pith 
No chlorophyll in woody cylinder. 
Do. 
_Do. 
Sparingly present in wood and pith 
