1gto) REED—TRANSPIRATION AND GROWTH OF WHEAT 103 _ 
From these results it would appear that the pyrogallol and tannic 
were responsible for very marked increases in transpiration, without 
causing correspondingly marked increase in green weight, in fact the 
average effect of tannic acid shows no increase in green weight. Where 
the action of these compounds upon soil extracts has been studied, 
they have been found to accelerate principally two things, transpira- 
tion and root growth. In this respect their effect resembles that of 
manure extract, as has been pointed out by SCHREINER and REED 
(13). From a rather extended study of this phenomenon under 
various conditions, it seems only logical to conclude that pyrogallol 
TABLE VI 
EFFECT oF PYROGALLOL UPON ROOT GROWTH, TOP GROWTH, AND TRANS- 
PIRATION IN TWO SOIL EXTRACTS 
Units te 
N : . | Weight of | won Weight | 'Tanspir 
No, Solution a aie conte at rp off seen pod ong 
eight 
t | Extract of soil “A” 100 100 100 100 100 
=f ame plus 2 p.p.m. pyrogallol 100 04 88 100 113 
3 | Same plus 4 p-p.m. pyrogallol 122 II4 85 46. [deh 
4 ame plus 8 p.p.m. pyrogallol 76 II7 81 156 94 
5 | Extract of soil “B” Ioo 100 100 100 100 
© | Same plus 2 p.p.m. pyrogallol | 119 98 95 104 125 
7 | Same plus 4 p.p.m. pyrogallol 138 116 99 143 140 
8 | Same plus 8 p-p-m. pyrogallol 152 132 106 171 143 
__,* The roots were taken from the solution, quickly dried between sheets of filter paper, and 
weighed. A small amount of capillary water was present, but the error is minimized by the fact that the 
figures given are comparative, not absolute. 
in a soil extract acts to improve the conditions for growth by acting 
upon deleterious organic compounds present in those extracts. In 
non-toxic distilled water, similar effects are not observed. The 
improvement in growth conditions which follows the action of pyro- 
gallol and other phenol derivatives is more quickly and markedly 
manifested by the roots than by the green parts of the plant (cf. 
the illustrations reproduced in the last-named publication). This 
point is well illustrated by an experiment whose results are presented 
in table VI. In this experiment pyrogallol was added at the rate of 
2, 4, and 8 parts per million to extracts of two soils taken from the 
€xperiment grounds of an experiment station. Soil “A” was taken 
from a rich cabbage field; soil “B” was taken from an unproduc- 
