1910] ~REED—TRANSPIRATION AND GROWTH OF WHEAT 105 
ous metals from the distilling apparatus, together with small amounts 
of volatile organic substances which pass over in an ordinary still, 
may show similar amelioration by treatment with absorbing agents. 
A representative instance is shown in table VII; other cases have 
been given by Livincston (9). 
TABLE VII 
EFFECT OF VARIOUS ABSORBING AGENTS UPON CORRELATIVE 
TRANSPIRATION OF 
EAT PLANTS GROWN IN DISTILLED WATER 
Units fot gra 
i transpi per 
No. Trans- Green i 
Treatment piration weight get 
: (relative) 
I Distilled water, control 100 100 100 
2 Distilled water, carbon treated 208 120 173 
3 | Distilled water, ferric hydrate 
treate 225 aay 196 
4 | Distilled water, quartz flour 
treated 245 135 aig 
These figures show among other things that the proportional 
transpiration was greatly increased by these treatments. It might 
be argued logically that the transpiration of the plants in the untreated 
distilled water is abnormally low, due to the probable presence of 
poisonous metals in the untreated distilled water, as such substances 
have the effect of depressing transpiration, while the transpiration 
of the plants in the treated solutions is normal. The removal of 
these substances by the absorbing solids leaves the solution in a 
better physiological condition for plant growth, as evidenced by the 
increased transpiration and green weight. The same result is also 
produced to a greater or less extent by redistillation in glass. 
Such treatments are generally accompanied by an increased root 
development, especially in branching, but as a rule this relation is 
not brought out in the dry weight of the roots, it being often found that 
4 set of long, well-branched roots weigh no more than a set of shorter, 
more poorly branched roots of the same number of plants, due to the 
8reater thickness of the latter. The weight of the fresh roots would 
be, however, a more accurate indication of the effect of the treatment, 
4S was shown in table VI. The longer and better branched roots in the 
culture solutions treated with absorbing solids are to be regarded as 
