98 BOTANICAL GAZETTE [FEBRUARY 
per cent MgO, while according to Pattapin (40) that of beech 
leaves was 7.20 per cent MgO, and according to Jost that of tobacco 
leaves was 7.36 per cent MgO. PALADIN states that 1.02 per 
cent of the dry weight of pea leaves was MgO, while 0.66 per cent 
of bean leaves was MgO. The writer found that 2.48 per cent 
of the dry weight of green leaves was MgO. In agreement with 
the results from cultures, the analytical data also indicated that 
the magnesium was in excess of the needs of the plant, and that 
decomposition of chlorophyll in these leaves was not due to a 
shortage in magnesium. 
The amount of calcium present in mottled leaves of Coleus 
was slightly greater than that in green, and the calcium content 
of both was less than that found in tobacco and beech leaves, 
while it was more than that found in pea and bean leaves. As 
TABLE VI 
CaLciuMm 
Sample Sam I P 
Leaf at no. ir pong 1 Average by weight 
SC a cee ew es 0.206 0.222 0.284 0.237 3-31 
MOLUGN Ae ee: 0.215 0.255 0. 283 0.251 3-93 
Motte Bo. oo 0.169 0,235 0.240 0.211 3.03 
calculated from table VI, the ash of green Coleus leaves was 33-2 
per cent CaO, while according to Jost that of tobacco leaves was 
36 per cent CaQ, and according to PALLADIN (40) that of beech 
leaves was 44.3 per cent CaO. Pariapin found that 3.21 per 
cent of the dry weight of pea leaves was CaO, and of bean leaves 
1.33 per cent was CaO. The increase of calcium (based on dry 
weight) from 3.31 per cent in the green Coleus leaves to 3.93 per 
cent in the mottled is easily accounted for by the fact that the 
older leaves have different ash constituents (44) from the young 
leaves. In beech leaves (40) the MgO content (based on dry 
weight) increased from 4.3 per cent in May to 5.6 per cent in 
July, and then decreased to 4.1 per cent in October. These data 
and the culture experiments showed that the amount of calcium 
present at all times was sufficient to care for the physiological 
needs of the plant. 
