“1902) 
than in Vicia sativa, 
THE RHEOTROPISM OF ROOTS 
195 
In this series the temperature was kept 
_ constant throughout at 23° in air, almost the optimum for the 
-ftowth of this species and variety; the velocity ranged from 
By 
‘ae 
a 
negatively, and ten grew 
vertically. Of the seventy- 
four positive roots, sixty- 
one attained an angle be- 
tween 45° and go°; several 
reached ° 
Among the Polygonaceae 
my Fagopyrum esculentum 
_ Some inclination to 
om Sudden curves in still 
wages Even though the 
-_ ‘Stow irregularly in 
a the contorted roots 
Mend their tips against 
Stream . short time after 
ee Twenty-six 
TOO Were selected 
and 22° in the air. 
: a Tanged from 
ia he 
2” Per minute, oe 
Ste 24, 18, and 12 hours. Twenty-four roots — : 
» and two negative. My notes record the angles _ 
n of these twenty-six roots: thirteen bent posi 
of 90°, one to an angle of 15°, and two bent 
s0* to 1380™ per minute and the period from 16 to 22 hours. 
Of the ninety-four roots used, seventy-four bent positively, ten 
Fic. 4.—Tracing ‘from a 
half natural size, of Vicia sativa. 
lings were packed in glass tubes with cotton 
wool, and the tubes held in il 
en bar. In order to secure a photo- — 
graph to show the curves to best advantage, 
the bar was suspended parallel to the water- 
photograph, 
The seed- 
stream. It was found, however, that the 
purpose of comparing the sensitiveness of 
this species with that of Raphanus sativ ee 
as shown in figs. 6 and 7, page 198. As is 
not unusual in this species, the figure shows — : - 
one root with a negative curve. 
