108 BOTANICAL GAZETTE [FEBRUARY 
to ascertain the relative amounts of photosynthetic activity in the 
green and mottled leaves. 
The green leaves gained 0.48 gm. (as dextrose) during the day, 
mottled A gained 0.074 gm., and mottled B 0.029 per 100 gm. of 
wet weight, which shows that the photosynthetic activity was 
greatly reduced by mottling. In the morning the carbohydrate 
content of the mottled leaves in all probability consisted mainly 
of substances of an aplastic nature, such as the hemicellulose of 
the cell wall which by hydrolysis forms galactose, xylose, mannose, 
etc. Since the carbohydrate content probably was made up mainly 
of substances of an aplastic nature, one would not expect them to 
be exhausted by respiration or to be translocated from the leaf. 
WILLSTATTER (table XXVIII) has shown that the carbon dioxide 
assimilated per hour was greatly reduced as the leaves yellowed. 
Water content and ash 
For each determination 20 gm. of fresh leaves was used; the 
leaves were dried at 100°C. and then ashed at a dull red heat. 
TABLE XX 
DRY WEIGHT 
Leaf Sample no. I Sample no. IT Average 
SO et, 7.92 6.88 #08 
BAUER A. cei tie 5.80 5.58 5.60 
PAOCGN os eos ee 5.76 6.60 6.20 
This decrease in dry weight is in harmony with the work of Bonc- 
QUET, or, in other words, leaves of mottled plants have a higher 
water content. WILLSTATTER (table XXVIII) showed that the 
water content of the leaves increased as yellowing progressed. 
This is due either to the fact that the materials were transported 
from the leaf or that respiration decreased the amount of dry matter 
present. 
Table XXI shows that the percentage of ash when calculated 
on the dry weight of the leaves increased 3—7 per cent during 
mottling. Analyses of leaves as given by Swart (48) show that 
as a rule the yellow leaves gave a larger percentage of ash than 
