242 HOW CROPS GROW. 
The roots of a plant make their first issue independently 
of the nutritive matters that may exist in their neighbor- 
hood. They are organized and put forth from the plant 
itself, no matter how fertile or sterile the medium that 
surrounds them. When they attain a certain develop- 
ment, they are ready to exercise their office of collecting 
food. If food be at hand, they absorb it, and, together 
with the entire plant, are nourished by it—they grow in 
consequence. The more abundant the food, the better they 
are nourished, and the more they multiply. The plant 
sends out rootlets in all directions; those which come in 
contact with food, live, enlarge, and ramify; those which 
find no nourishment, remain undeveloped or perish. 
The Quantity of Roots actually attached to any plant 
is usually far greater than can be estimated by roughly 
lifting them from the soil. To extricate the roots of 
wheat or clover, for example, from the earth, completely, 
is a matter of no little difficulty. Schubart has made the 
most satisfactory observations we possess on the roots of 
several important crops, growing in the field. He sepa- 
rated them from the soil by the following expedient: An 
excavation was made in the field to the depth of 6 feet, and 
a stream of water was directed against the vertical wall 
of soil until it was washed away, so that the roots of the 
plants growing in it were laid bare. The roots thus ex- 
posed in a field of rye, in one of beans, and in a bed of gar- 
den peas, presented the appearance of a mat or felt of white 
fibers, to a depth of about 4 feet from the surface of the 
ground. The roots of winter wheat he observed as deep 
as 7 feet, in a light subsoil, forty-seven days after sowing. 
The depth of the roots of winter wheat, winter rye, and 
winter colza, as well as of clover, was 3-4 feet. The roots 
of clover, one year old, were 34 feet long, those of two- 
year-old clover but 4 inches longer. The quantity of roots 
in per cent of the entire plant in the dry state was found 
to be as follows, (Chem. Ackersmann, I, p. 193.) 
