198 BOTANICAL GAZETTE [ance 
negatively to an angle of 20°, giving a percentage of ninety- 
in four positive roots. 
Raphanus sativus, the variety 
known as the “early long scar- 
let,’’ has been for me the best 
of all plants for experiments” 
with rheotropism. Itis larger 
than any of the other Cruci- 
F Raphanus sativus before the ferae worked with, and 
beginning of thé experiment which gavethe that reason less liable toinjuty 
result in fg. 7. Tracing from photograph. in handling. Its roots ate 
insensitive to light, and hence experiments with it may be co 
ducted in the general rooms 
of the laboratory. In the series 
described here, 140 seedlings 
have been used in nine experi- 
ments with the revolving ba- 
sins of water. The water tem- 
perature has ranged from 20° 
to 25°, the velocity from 50™ 
to 750™ per minute, and the 
period from 5 to 33 hours. 
One hundred and twenty-three 
roots have bent prey. the = go Rophowus 
Majority from 45° to 90°; eight a photograph _ This gue scr . 
have bent negatively, and nine wien om pees of Vicia peor 
have grown vertically. The ~ prrars ger carried 
experl riments for lution 
positive roots are, therefore, i time, the period geo 19 
_ 87 per cent. The response of DY ars, the temper es ~~ 
thes plant to the water stream per ego copes ‘ 
os relatively very ready. Two Biv geome curv es are mallet 
hours from the beginning, at — eset sith the stream 
a suitable temperature, well a 
marked curves can be detected in 25 per cent. to gar” 
_ the roots. The relative response of this plant a ge 
s hee well shown es comparing jigs. 4 and es . 
2 ie be continued. L 
