224 MR. F, DARWIN ON THE CONNECTION 
Cut Roots. 
Percentage Percentage 
Length, growth in growth in 
millim. 3 hours. 3 more hours. 
L 27 10 27 
Mb iie 26 3 26 
Hi ers 27 4 17 
n5 E 2:6 4 20 
Average...... 53 225 
Normal Roots *. 
nb ddnde 2:6 21 29 
MIS $0. 28 8 30 
Ch 05005 2:8 20 39 
Average...... 16:3 327 
Here the growth of the normal roots was much more vigorous 
during both periods. During the first period we have :—Nor- 
mal : cut :: 100 : 33. For the second period :— Normal : cut 
:: 100 : 69. This experiment shows, however, some power of 
recovery in the “cut” roots. 
Experiment V.—Roots 2-3 centim. in length; marked at 
2 and 5 millim. from the tip, and the intervening space of about 
3 millim. measured as before; 1:5 millim. cut off 3 roots. They 
were all grown vertically in damp air. Inthis way it was possible 
to continue microscopical measurements for longer periods; in 
the former experiments tbe uncut roots became geotropic, and had 
to be measured with a millimeter-scale or with compasses in the 
later periods. The present plan has the disadvantage that we do 
not know whether the roots become geotropic or not. 
Cut Roots. 
Percentage 
gu Percentage Percentage Percentage growth in 
yerum growthin  growthin3  growthin3  21h.40m. 
3 hours. more hours. more hours. from the 
millim beginning 
L 7. 2:6 3 13 38 198 
Hi 2:6 1 10 15 155 
nh a 24 2 5 4 117 
Average ...... 2 15 24 176:5 
The average of the eut roots is taken from i. and ii., because iii. grew so differ- 
ently from the others that itis probably abnormal. If iii. is taken into the 
averages, we have for the four columns 
2 93 173 1567 
* In this case only three of the normal roots were measured. 
