Tue Errect oF MANGANESE COMPOUNDS ON SOILS AND PLANTS 381 
Then bleaching occurs in small patches, which redden, dry, and turn brown. 
The intensity of this chlorotic condition decreases with the decrease in 
the concentration of the manganese. The roots of the plants grown in 
concentrations of 1000 parts per million turned brown in spots, especially 
at the tips, within four days. This browning occurred on the roots 
of all the plants except the checks, the length of time before the browning 
appeared being proportional to the concentration of the manganese. 
The toxic effect was not so great in cultures of manganese sulfate con- 
taining nutrient salts (4656 parts per million) as in pure solutions, as is 
shown in table 2: 
TABLE 2. ManGaANESE SULFATE ADDED TO NUTRIENT SOLUTIONS CONTAINING 4656 Parts 
PER MiLuion oF NUTRIENT SALTS 
Length Weight of four plants Total 
Parts per million (in centimeters) (in grams) a e Relative 
of manganese my weights 
weight 
Leaves Roots Leaves Roots 
Us 6s ORCC eee 19.4 12.0 1713 .0742 . 2455 100 
Qa SiS CEO Ie 17.8 15.4 2951 . 2033 . 4984 203 
2D) oO aCe 19.2 15.6 . 2668 .1781 4449 181 
(0 5.0 SO SG Ree eae Dil 14.0 . 2383 . 1294 .38077 150 
Do coe ee eee 20.5 12.8 2250 . 1052 . 33802 135 
HNO s SaaS cone see 20.7 9.3 . 2020 .0780 . 2800 114 
‘CO ase eee Be; 16.0 5.9 1581 0459 2040 83 
This demonstrates the ameliorating effect of the nutrient salts in over- 
coming or reducing the toxicity of a plant poison. At 1000 parts per 
million the total dry matter was reduced, but it equaled the check at 
400 parts per million and increased with a decrease in the concentration 
of the manganese. The yellowing of the tips of the leaves at 1000 parts 
per million commenced in nine days. The browning of the roots was not 
observed in any of the cultures except those of greatest manganese content. 
A second series of cultures was run in which the chloride, the carbonate, 
and the dioxide of manganese were used in addition to the sulfate. The 
seedlings of the first series, reported as having grown in solutions con- 
taining no nutrient salts, were in reality not grown in the absence of other 
elements. That the effect of the storage food in the endosperms is a 
factor in work of this nature, is suggested by McCool (1913), who states: 
Pea seedlings [cotyledons not removed] that have been grown for ten days in distilled 
water, tap water, and full nutrient solution, respectively, are much more resistant to the 
