1921] SCHERTZ—MOTTLING 105 
compounds were rapidly: being broken down. In this connection 
SAMPSON (43) showed that the amino acid nitrogen of Coleus 
(based on dry weight) increased from 0.056 to 0.072 per cent as 
the leaves mottled. Table XIV shows further that when the 
leaves were completely mottled the nitrate nitrogen almost dis- 
appeared, which is in complete accord with the microchemical 
determinations. The table shows also that inorganic forms of 
nitrates were used up before the protein nitrogen was exhausted. 
PALLADIN shows that such was the case in starving plants. Bonc- 
QUET (4) believed that the plants he worked on were starving, due 
to lack of nitrogen. 
Free ammonia was determined by a modification of the Form 
method (35). Twenty-five gm. of. the fresh leaves was finely 
ground with quartz sand, placed in an aeration tube, and ammonia- 
TABLE XV 
FREE AMMONIA 
Nitrogen 
Sample Sample Sample 
Leaf no.I no. II no. Average policed oy 
MO ie ee: None None None None None 
MOM A None None None None None 
ME Bs ©.000,18 | 0.000,14 | 9.000,21 | 0.000,18 | 0.003,25 
free air drawn through the tube for 2 hours. The ammonia which 
came from the leaves was absorbed in an aeration tube which 
contained o.1N H,SO,. The ammonia set free was distilled off, 
after adding NaOH, and Nesslerized (33). Especial care was 
taken to use materials absolutely free from ammonia. The 
ammonia is calculated as grams of nitrogen per 100 gm. of wet 
weight. For the analysis leaves were selected which were free 
from mechanical injuries or drying at the tips. The mottled leaves 
A still had some green in them, while those of B were wholly 
yellow. 
Other forms of ammonia were determined, such as albuminoid 
ammonia. The method as outlined by Mason (33) was followed, 
in which ro gm. of the fresh leaves was distilled in the presence of 
NaOH and KMn0O,, 600 cc. of distillate distilled off and then a 
portion of it Nesslerized. The results calculated as grams of 
