BETWEEN GEOTROPISM AND GROWTH, 221 
Normal Roots. 
Percentage Percentage 
Original growth in growth in 
lengths. lh. 50m. 2h, 20m. additional. 
millim, 
l. no 30 8 5 
Yİ ......... 27 7 5 
Mi. min. 28 8 13 
Average... 77 77 
If we compare the rates of growth during the first period, we 
have :— 
Normal roots 7°7, cut 4°7; or as 100 to 61. 
For the second period we have :— 
Normal roots 7:7, cut 14; or as 100 to 182. 
If we take the growth during the whole period, we have the 
averages :—- 
Normal roots 16, cut 19:7; or as 100 to 123. 
This experiment is unsatisfactory in one way, because the 
measured space was taken too far from the apex of the root. 
Moreover, for some reason not even the uninjured roots became 
properly geotropic. Nevertheless the experiment shows that the 
effect of the operation lasts only a short time, and that as the 
“cut” roots recover, they may actually grow more quickly than 
the normal ones. 
Experiment II.—In this case the roots were marked at 
(roughly) 2 millim. and 5 millim. from the apex; so that the 
measured space of about 3 millim. was nearer the apex than 
in the former experiment. Otherwise the conditions were as 
before. 
Cut Roots. 
Length of Percentage Percentage ` Percentage 
measured growth in growth after growth during 
space, 4 h. 43m. 2 h. 12m. 12h. 10 m. 
millim, additional. from beginning. 
L... 26 2 5 71 
a... 29 4 6 73 
mm... 28 11 I1 rit 
Average...... 80 73 737 
Normal Roots. 
i 94 18 18 12o 
BÉ. 27 11 11 54 
Average......14'5 14:5 : 88:5 
In this experiment the effect of &utting off the tips lasted 
longer than in experiment I. ; for during the first two periods the 
