314 New combe. — Geo tropic Response at Various 
and the fairest one, and that is given here. The total number of hypocotyls 
stimulated at 90° was forty-one, and the same number was stimulated at 
135 0 from the position of stable equilibrium. After the stimulation for 
1 7i min., or for 20 min., and the subsequent rotation on the klinostat 
for 30 min., twenty-four geotropic curves were observed in those exposed 
at 90°, and thirteen curves in those exposed at 135 0 . In only one of the five 
experiments did the number of curves in the seedlings stimulated at 135 0 
equal those in the seedlings stimulated at 90° ; and that was in the last 
experiment, where each pot of seven seedlings showed only one curve. In 
amplitude of angle the curves formed in response to the stimulation at 90° 
were certainly the larger on the average ; but there was a great deal of 
individual variation, and the evidence in this direction was not very strong, 
though more careful measurements might lead to stronger evidence. 
Two pots of seedlings of Raphanus sativus, L., were used in the same way 
as the foregoing Brassica seedlings. The latent period at 22° C. was found 
to be 25 min. for the first stems to curve. In one pot, eighteen hypocotyls 
were stimulated in the horizontal position ; while in the other, seventeen 
were placed 135 0 from their position of stable equilibrium. After lying 
20 min. in these positions, and then revolving for 40 min. on the klinostat, 
each pot showed eleven hypocotyls curved geotropically. After revolving 
on the klinostat for 60 min., eleven of the eighteen stimulated at 90° were 
curved, while seven of those stimulated at 135 0 were curved. 
The same seedlings just described were allowed to stand for 1 hour 
and 30 min. and were used again as before. Stimulation was for 1 5 min. 
only; the seedlings that were laid at 90° before now being placed at 135°, 
and those before at 135 0 now being at 90°. The largest number of curves 
in each pot came after 45 min. of revolution on the klinostat ; then those 
seedlings stimulated at 90° showed four curves, those at 135° one curve. 
Subsequently all the hypocotyls began to straighten. 
The foregoing results cannot be said to furnish conclusive evidence 
for either the position at 90° or that at 135 0 as giving the stronger geotropic 
response. The indications, however, point to the horizontal position as the 
more effective, since the larger number of curves and the larger angles came 
in response to that position. 
2. Determination of the angle for maximum response by the method 
of alternate stimulation. 
Alternation at 90° and 135 0 . — To facilitate this alternate stimulation 
there was constructed a device consisting of a heavy board base, rising about 
a foot, to the top of which was hinged a board capable of a rotation of 135 0 
about a horizontal axis. . The base and hinged board were 5 feet in length, 
thus giving room for several plant pots or damp chambers at one time. 
The hinged board was pierced by holes to receive the small plant crocks, 
and was provided with hooks and wires to allow ready means of securing 
