1921} SCHERTZ—MOTTLING 10g 
the green ones. One might construe this to mean that materials 
are not transported from the leaf as it yellows, for if they were 
transported, presumably the salts would be carried along and the 
ash would decrease. It seems more probable that since the assimi- 
lative activity is reduced, the respiratory products pass off as 
gas and so leave the salts behind. Boncquet (4) found that 
plants affected with nitrogen starvation have a higher percentage of 
ash (when based on dry weight) than normal plants, as is shown by 
beets, tobacco, and potatoes. 
SCHULZE and Scutitz (44) have shown that the ash content of 
leaves of Acer Negundo increases as autumn approaches. The 
TABLE XXI 
ASH 
Grams ash per 
Leaf Sample no. I | Sample no. IT Average too gm. 
dry weight 
NEUES HAGE pee ito 1.05 0.89 9.97 13.8 
Mottled Ae eras 0.97 0.93 0.95 16.7 
WOU Bie i 6 os cate sans 1.23 1.32 1.28 20.7 
TABLE XXII 
ASH IN DRY SUBSTANCE 
| May June july August | September! September 
7 6 5 2 3 25 
Percentage of ash......... 7.33 7-52 8.06 dei | 9-43 | ara 
ash of the leaves increased 4 per cent, while the ash of Coleus 
leaves increased 3-7 per cent. Ash of the plane tree leaves per 
unit area of leaf was shown by TucKER and ToLLEens (49) to 
increase gradually until Oetober 8, after which there was a slight 
decrease. 
Catalase 
In determinations of catalase activity only the blades of Coleus, 
exclusive of the primary veins, were used. For each determination 
©.5 gm. of the leaf material was ground for 2 minutes with a little 
quartz sand and powdered calcium carbonate as a neutralizer. 
The determination was run according to the method described by 
