BETWEEN GEOTROPISM AND GROWTH. 229 
Split Roots. 
Original length Percentage 
of measured rowth in 
portion. 25 hours. 
millim, 
E S Cu 8:5 148 
I. 5x: nl 8:2 80 
Mh ec. 82 198 
liv. e etek 80 143 
V: ILC S 80 200 
Average ...... 1528 
Cut Roots. 
üni 82 244 
M sss 80 275 
nb clie 80 213 
1V. cite EE 8:1 172 
Vel S ns s een 8:5 230 
Average ...... 226:8 
The ratio between the average growths of the two sets is 
None of the “ cut ” roots became clearly geotropic ; iv. and v. had 
their terminal parts bent so as to be 10-15“ below the horizon ; 
i., iL, and iii. remained horizontal. Of the split roots, i. was 
bent at right angles in a horizontal plane; ii. was eurved down- 
wards so as to be 80° below the horizon; iii. distinctly curved 
downwards ; iv. was 45° below the horizon; v. pointed nearly 
vertically downwards. 
These experiments show conclusively that there is no necessary 
connection between vigour of growth and power of curving 
geotropically. If Wiesner were right in explaining the loss of 
geotropism in “cut” roots to retarded growth, it is clear that 
split roots ought to be even less geotropic, since their growth 
is markedly less vigorous than that of cut roots. But I have 
shown that the reverse of this is the case: Wiesner's argument 
therefore falls to the ground. 
I have already quoted the opinion of Sachs that the partial loss 
of geotropism of roots grown in damp air is not connected with 
their diminished rate of growth. This point of view leads on to 
what seems the rational way of looking at the question, namely, 
that geotropism, though accompanied and carried into effect 
by growth, cannot be treated as a mere distribution of growth of 
