> agen. THE RHEOTROPISM OF ROOTS 193 
In Tnticum vulgare ninety-three roots were observed, divided 
_ among three experiments. Temperature of the water was from 
_ 19° to 22°, velocity from 75°™ to 750™ per minute (constant for 
_ ayone root), period 24 hours for two experiments, and 48 hours 
forthe third. Twenty-five roots were positive, three were nega- 
__ tive, and sixty-five were neutral. The angles attained were not 
_ More than 20° from the vertical. This would seem to place the 
_ wheat among those of weak response to a current of water. 
Secale cereale furnished sixty-two roots for observation, tem- 
perature of water 20° to 23°, velocity 100° to 1000™ per minute, 
period of 15 hours. Fifty-nine roots were positive and three 
neutral. Several of the angles attained were go°. 
: _ Hordeum vulgare had 102 roots under experiment in a water 
: ‘temperature of 20° to 22°, a velocity of 50™ to 750™ per minute, 
and periods of 7,9, and 24 hours. Of positive roots there were 
tighty-four, hegative seven, and neutral eleven. 
Avena Sativa was tested in five experiments with a total of 
eta The water temperature was 21° to 25°, the velocity 
ee tO. L000 per minute, and the period 9 hours to 
ours. Ninety-seven roots bent positively, six negatively, 
ty-nine remained neutral. Many of the roots bent to 
of 60°. : z 
© four species of Gramineae just considered resemble 
oe ae the production of good roots in water, in display-. 
ve theotropism, and in producing a considerable per- 
: » Meutral roots. The wheat shows the smallest number 
P iE of these four plants. : 
fag emiosee, ten species have been studied, five 
non-responsive, and five responsive. All but the — 
~ Sensitive specie : 
t Sativa was 
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