1902] THE RHEOTROPISM OF ROOTS 275 
fact that when several seedlings have their roots laid horizontally 
so as to carry out the geotropic curve, some roots bend at 
angles varying from those of the majority, indicating either an 
individualism in sensitiveness or in response. The rheotropic 
response shows like variation. In general, the most rapidly 
growing roots are the first to : 
respond, but in nearly every a 
experiment there are found | <i 
foots varying their time of | 
response from that of their fel- 1 Y 1 1 
lows of equally rapid growth. 
This fact is illustrated by jigs. Fic. 9.—Raphanus sativus, tracing from 
gand zo. It is easy to see 4 photograph. Seedlings ready for the 
that root no. 5 has grown most experiment whose result is shown in fig. 70. 
aad also curved most; but root no. 2 has grown less and 
bent more than no. I, and no. 6 has grown less and bent 
= ge than no. 7. It is true that in these cases external condi- 
: Hons were not precisely similar, for the velocity of current for 
7 ee some of the roots was 675™ 
and for others 725™ per min-— 
ute, disregarding the irregu- 
larities of current caused by 
the roots themselves. How- 
: <— exactly the same theoretical — : 
: ina om 7 rf rate of flow as no. 4, must — 
" pig ‘ —— 1% hours after placing 
- tere of 21° “eed stream with a tempera- og ee 
bet ming nd? Velocity of 675° to 725m roots in front of it than did . 
Ge, SHOW ‘initial rheotropic no. 4, and grew less than no. — 
- aigle, Oni : 4; yet it curved to a greater — 
oe a the other hand, many of these variations in physi- : 
reaction could probably be reduced were care taken in 
- 
m to be similar whose past development and Lege’ es) 
: ‘ 7 *sffect of the theotropic stimulus is shorter than the 
| | <— ever, root no. 2 was in almost 
Aedhanus sativus, traced from have felt more of the irregu-— a 
larity of flow caused by the 3 
