New Yorx AcricuttruraL Experiment Strarion. 467 
the influence of gravity, air, heat, light, moisture, food and 
chemical compounds. So sensitive are roots to external condi- 
tions that it may be laid down as a law that the character of a 
root system is directly determined by the interaction between 
the specific peculiarities of the plant itself and of its environ- 
ment. Thus in size, position, and shape a root system is 
greatly modified by the external conditions. In the experi- 
ment in hand it is the root systein that comes in first and most 
direct contact with the differing factors in the management of 
the trees of the two plats. The apple trees were forced to 
accommodate their root systems to the conditions given in the 
two plats of the experiment. In what condition did ‘the two 
treatments leave the roots at the end of the five years? We 
can give fairly definite answer as regards position and shape 
but as to size of the roots we can only roughly estimate. 
Position of roots.—In position the roots of the trees in the 
sod-mulch plat came to the very surface of the ground, often- 
times being found in the decaying mulch. The great mass of 
the feeding roots in this plat lie close to the surface though 
straggling roots, rootlets and roothairs go to the full depth 
of the foot of the light soil of which this land is composed. 
Whether the destruction of these surface feeding rootlets by 
cold in winter and heat and drought in summer greatly af- 
fected the vigor of the trees and helped to bring about the evil 
effects of the sod-mulch treatment cannot be said. It is not 
likely that cold contributed much to the injury of the sodded 
trees but the death of many of these surface roots in hot, dry 
weather must have lessened the vitality of the trees at a most 
critical time for the welfare of crop and plant. In the tilled 
land the roots were to be found in greatest abundance at a 
depth of from three to ten inches, with some running deeper. 
The plow and cultivator kept them from coming nearer the 
surface, though, since plants direct their root-tips to places 
where food and water are most abundant and with cultivation 
water at least would be most abundant under the earth mulch, 
it is doubtful if many roots pass into the mulch made by the 
cultivator. 
