( 69 ) 
Inconsequence of the nature of the experiment. The results for a 
i^ertical and for a horizontal axis are in agreement. For forces with 
small accelerations (0.12 g. and below) the intensity of the curvature 
becomes smaller and smaller, and finally (below 0.8 g.) it is difficult 
to judge. This perhaps explains a difference between Bach’s results 
and my own for forces with accelerations below 0.7 g. In those cases 
| Bach finds presentation times, which are relatively too high. He 
t however also finds the reaction times longer than I do in the 
^ corresponding cases. For instance Bach found (with Vicia Faba)i or 
0.3 g. a reaction time of l h .55 / , i. e. 59% longer than the reaction 
time for 1 g. I found myself (with Avena sativa) for 0.28 g. a 
reaction time of 50' i. e. 10 % longer than the reaction time for 
1 g. Similarly Bach: for 0.06g. a reaction time which is 188% 
longer than that for 1 g.; I for 0.06 g. a reaction time which is 
147 % longer. 
| The roots of Vicia Faba are certainly a less sensitive material 
than the coleoptiles of Avena. Perhaps Bach stimulated in these 
cases for a somewhat longer time than the presentation time, in 
order to obtain curvatures which could be observed very clearly. 
The experiments are especially in this part of his investigation not 
, sufficiently numerous to be convincing. 
| His attempt to explain the values which to him also appeared 
abnormally high, is certainly not justified, since it assumes, without 
any experimental basis, that there is a difference in the perception 
of the stimulus depending on whether the centrifuge has a vertical 
or a horizontal axis. In my own experiments I have not observed 
any such difference as will be seen from the above figures. 
It follows from all these figures for centrifugal forces and for 
various inclinations, that the relationship, which it was thought could 
be deduced from Bach’s experiments, does indeed exist. 
I have also carried out some experiments with roots, namely with 
roots of Lepidium sativum , which were grown according to Buder’s 
method 1 ). I obtained with these the following results: 
Presentation time Product * n 
•/-seconds 
Corresponding Acceleration 
9 X sin 90° = <7X1 
gX*in 45° = <7 X 0-7071 
gXsin 135° =^X 0.7071 
9 X sin 30° = <7 X 0.5 
</X^ 150° = <7X0.5 
gXsin 15° = g X 0.259 
9 X sin 165° = ^X0.259 
J. Buder, Ber, 
355" 
544" 
525" 
715" 
700" 
1460" 
1370" 
Deutschen Bot. Geselisch. XXVI. 1908, p. 164. 
