CHAPTER IV 
GROWTH OF THE ROOT AND STEM 
The part of the root which lengthens. One of the 
interesting things 

FIG. 48. Marrow seedlings, 
the root marked in left. 
Right one showing where 
growth took place in 
twenty-four hours. 
about the root is the way it grows 
in length. We know that as the 
‘root becomes longer the tip moves 
along. But does this take place by 
a constant lengthening of the ex- 
treme tip of the root? Or is the 
tip pushed along through the soil 
by the growth or stretching of some 
other part of the root? We can 
answer this if we examine the seed- — 
lings which are growing in germina- 
tors, as in the lamp chimney, where 
the roots are not covered with soil. 
To tell where the root elongates. 
Take a fine pen and some indelible 
or water-proof ink. Beginning at 
the tip of the root, mark off on one 
side very short spaces, as close t0- 
gether as possible, the first 1mm.’ 
from the tip, and the others | mm. 
Pi, sat inch. 
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