- _ ¢alled neutral. 
one might expect a low degree of individua 
274 BOTANICAL GAZETTE [APRIL 
plants the latent period is shortest in velocities between 100" 
and 400™ per minute. Raphanus sativus and Vicia faba, however, S 
have shown their shortest latent period in velocities above 400" 
and below 750°" per minute. The influence of velocity on the 
time of response is shown in a striking way by using the basin 
of water, revolving at arate to give critical velocities in the 
radius, and by suspending a row of seedlings along the radius. 
From scores of such experiments, two may be selected here. 
In the first, the revolution was twice to the minute, giving along 
a radius velocities from 25°™ to 125°™ per minute. The tempera 
ture in water was 22°, and twelve seedlings of Raphanus sativus 
were employed. In two hours the three outermost seedlings had 
bent + ; inthree hours the three outermost were +; im om : 
and one-half hours the six outermost were +; and in seven or 
hours the seven outermost were + , while the remaining five — 
nearer the center were all neutral. Inthe second selection, seed: 
lings of Brassica alba were used. The temperature in water WS 
23°, the revolution 24 times to the minute, and the veloc? : 
ranged from 300% to 1500™ per minute. After three hours the : 
three roots nearest the center of the basin were 1 after 2 
hours the six nearest the center were + ; and after fifteen hows” 
_ the eight nearest the center were +; while the fourteen vane 
_ most were all directed vertically downward and therefare © 
_ The foregoing considerations have shown us that be 
response stands in definite relations to the veoats ee 
We may at this point inquire whether the variation in eo 
of response in constant external conditions may be ei 
_ wholly to variation in the rate of growth. A seedling ' gare 
regarded as so low an organism among © zed bell 
lization, 
€xpect constant results in constant conditions ee 
environment. Could we not carry on our ¢* 
_ otropism quantitatively, and thereby look for com ay 
_ periods and constant angles? The experience | poner 
is against such an assumption. Every one 18 1°" 
