74-8 Hi ley, — On the Value of Different Degrees of 
was required with normal gravitational stimulus in the opposite direction in 
order to counteract the tendency to bend outwards. 
This result may be expressed as follows : When acted upon by a high 
centrifugal force roots at first perceive the stimulus fully, and the tendency 
to respond is proportional to the stimulating force. But after stimulation 
has proceeded for a certain time the tendency to respond falls off, and 
subsequent minutes are much less effective in their stimulating power. The 
actual period of stimulation by the centrifugal force (i. e. T) in Experi- 
ments io to 1 8 is always less than i min. ; in all the experiments summed 
up in Table II, T is more than 2 min. Comparing Experiment 13 (in 
which T = 38 sec.) with Experiment 22 (in which T = 121 sec.) it will be 
seen that the radicle tends to respond proportionally to the stimulus when 
it lasts for 38 sec., but not when it lasts for 121 sec. Thus the failure 
to respond fully begins before the expiration of two minutes. 
Experiments with Cucurbita Pepo. 
A few experiments were also done with the Marrow ; and the following results 
were obtained. The seeds were first soaked in water in a dish placed on the hot- 
water pipes for a day and were then transferred to a pan containing sand. They 
need a high temperature (20°-30° C.) to germinate, and are usually ready for experi- 
mentation three days from the commencement of soaking. 
Experiment i. Dec. 10, 1912. 10.5 a.m. to 3.40 p.m. 
Radius of rotation at middle of box = 7 cm. 
0 = IIO°. 
Total period (/+ T) = 7 m. 43 s. 
^=3-8- 
R - 3 - 93 - 
Point of equilibrium is 1*5 cm. below middle of box. 
r — 5.5 cm. 
Cent, force = 3-42 mg. 
C = 3-42 cos 2o° + sin 20° = 3-56 mg. 
CT 
Experiment 2. Dec. 12, 1912. 2.10 p.m. to 10.45 P- m * 
Radius of rotation at middle of box = 1 1 cm. 
6 = 102 °. 
Total period (/+ T) = 5 m. 
t 
f- 5 ' 6 4 - 
R = 3 ' 93 - 
Point of equilibrium is 2-5 cm. below middle of box. 
.*. r = 8*5 cm. 
