1285 
20 minutes. Examination took place 55 minutes after its end. As 
in the former section the horizontal deviation of the apex in mm. 
is given as a measure of the curvature. 
rn 
| | | 
| ! min. (150) 30sec. 5), = 
EE Sey ee eee ee ee ae 
20 min. (3000) ,10 min. (1500) 5 min. (750) 2.5 min. (375) 
| | 
0.5 yy EA | dere LD Bd SLA 1.4 
| | 
These figures were contirmed in different series of experiments. 
In these it was further noticed that the curvatures arose every where 
at the same time and at first also increased at the same rate. 
Thus further observations were suggested with the object of seeing 
to what these differences arising in the course of the curvature- 
process might lead. 
In the following table the magnitude of curvature after 40 minutes 
and after 2 bours are placed side by side. 
Curvature 
Duration of Strength of 
illumination | illumination ent On After 40/ Aster 2 Ben 
Boden Me ishet 750 | os | —0.9 (0.1) 
150 eran ME 375 RE en ACN 
180 ,„ ijs LMG | 22.5 20e | = 
0, nen MIE Sel 11.25 Shits Ed 
Not illuminated | | anda 0 OLA) 
The duration of the geotropic stimulation amounted to 380 min. 
Seedlings which were illuminated beforehand. with 750 and 375 
M.C.S., showed a clear S-shape after 2 hours. The apex of those 
that were not illuminated, was quite straight. The figures given are 
the apex-curvatures. Placed after in brackets are the figures which 
indicate the amount of the remainder of the original curvature, 
calculated on the assumption that the apex was straight. The anta- 
gonistic geotropic curvature was not yet measurable as is shown 
by the last line. The curvatures of the previously illuminated seed- 
lings cannot therefore be ascribed to this cause. Experiments in 
which, after the cessation of geotropic stimulations, plants were 
placed on the ¢linostat, have indeed convincingly proved that without 
. 8 
