750 Hiley .—On the Value of Different Degrees of 
Experiment 6. Dec. 1 6 , 1912. 5.44 p.m. to 10.5 p.m. 
Radius of rotation at middle of box = 25 cm. 
0 = 95° 
Total period (/+ T) — n m. 
/ 
I 5*6. 
R = 3.97. 
Point of equilibrium is at middle of box. 
.*. r = 25 cm. 
C = 15*9 m g- 
M.E.C. = 0-94. 
C (corrected) = 14-9 mg. 
TABLE III. 
Cucurbita Pepo radicles. Temp, about 20° C. 
No. of 
c 
t 
CT 
Exp. 
mg 
T 
I'+Z) 
m. s. 
mg.t 
1 
3-56 
3*8 
7 
43 
0.94 
2 
5-37 
5*64 
5 
0 
o*95 
3 
11*28 
u-5 
1 1 
0 
0*98 
4 
12*5 
12*8 
1 1 
0 
0*98 
5 
14*0 
13*4 
5 
30 
1*04 
6 
14.9 15.6 
CT 
Average value of = 
mg.t 
1 1 
= 0-97. 
0 
0*96 
Conclusions. 
To obtain a clear idea of the place of the results obtained from this 
research in the science of geotropism, it is necessary to compare them with 
the results of other investigators in the same subject. Unfortunately, 
owing to the indefiniteness of our knowledge to-day, this is not easy to do. 
When Czapek (’98), Bach (’07), Pekelharing (’09), Rutgers (TO), and others 
had given us a definite conception of presentation time and reaction time, 
with sufficient data on which to base theories of graviperception, another 
school, represented by Polowzow (’09), Arisz (11), and Trondle (13) makes 
us sceptical about all previous work on this subject by maintaining that 
presentation time and reaction time are artificial concepts founded on the 
fallibility of our unaided vision. They hold that whilst presentation time 
may be regarded as the least time of exposure to a geotropic stimulus 
which will cause a response visible to the naked eye , and reaction time as the 
period which elapses from the first exposure to stimulus to the time when 
response becomes visible to the naked eye , yet, as a matter of fact, response 
