126 BOTANICAL GAZETTE [FEBRUARY 
plant tissue by LAURENT (22), ABELOUS and ALOoy (23), KASTLE 
and ELvove (24), and IrvING and HANKINSON (25). LAURENT 
claims that young seedlings of maize, white lupine, and peas have 
a reducing action on nitrates, while Irvinc and HANKINSON have 
found that a number of plants reduce nitrates more or less. 
SODIUM SELENITE.—Sodium selenite was next employed as a 
test solution. Solutions of sodium selenite of 0.25 per cent were 
first used. The solutions reacted alkaline to litmus and phenol- 
phthalein, and were toxic to the young seedling. When neutralized 
by hydrochloric acid, however, the toxicity of the selenite was 
greatly lessened. When seedlings were grown in the sodium selenite 
solution made neutral or slightly acid to phenolphthalein and of a 
strength of 0.125 to 0.25 per cent, the parenchyma cells of the end 
of the root cap were colored an intense pink in a few hours, varying 
with the seedlings, by the deposit of selenium. This deposit was 
more marked in slightly acid solutions. The points of emergence of 
the secondary roots were likewise colored. Later the whole root 
became colored. 
SODIUM TELLURITE.—When sodium tellurite is used as a test 
for reduction, the roots are colored a blue-black by the deposit of 
metallic tellurium, otherwise its behavior is like that of sodium 
selenite. 
These experiments show conclusively that the intact roots 
possess a reducing power. This reducing power is stronger in the 
young seedling, being much stronger in the seedling 4 days old 
than in the seedling 12 days old. As judged by the quickness with — 
which the deposit of selenium is made on the roots and the extent 
and intensity of the deposit, the reducing power increases from 
_ time of germination to the sixth or eighth day and then decreases. 
It is still present in seedlings 13 days old, the oldest seedlings 
examined. The oxidizing power of the wheat seedlings, on the other 
hand, as judged by the oxidation of aloin, is less in the young seed- 
ling and increases with age, being considerably greater in the 
twelve-day seedling than in the six-day seedling, and still greater 
than in the case of the four-day seedling. ce 
Dying tissue tends to have a reducing action. The reducimg — 
action of the wheat roots on sodium selenite, however, is not 4 — 
