9i 
Tropistic Movements of Plants. 
other when the roots were stimulated for thirty minutes. In this way it can 
also be established that the anti-ferment reaction is much weaker at 45 0 than 
at 135 0 , i. e. at the same distance from the horizontal position in the upper 
quadrant. But between 6o° and 120° no difference could be detected, nor 
any distinct difference between 90° and 135°. The stimulus can be still 
more diminished if the roots after six minutes’ stimulation stand vertically 
as long as possible. They may be even left vertical for three to four hours, 
since, as above shown, the anti-ferment reaction is not destroyed in such 
a period. Experiments carried out in this manner demonstrate that the 
anti-ferment reaction at 6o° is distinctly weaker than at either 90° or 120°, 
and some experiments established a stronger anti-ferment reaction at 
I 35 -i 5 ° 0 than in the horizontal position. The result of the anti-ferment test, 
therefore, can be taken as supporting my own view and that of Darwin ( 13 ), 
D. Pertz ( 14 ), and Nemec ( 15 ), that the positions obliquely upwards give 
a stronger geotropic stimulus to roots than the horizontal position. The 
detailed experimental proof of the results here only briefly communicated 
is reserved for an extensive paper to be published in German. Here I am 
restricting the discussion to the chief points of importance. 
VI. 
The behaviour of roots on the klinostat was found to be of great interest 
in reference to the anti-ferment test. I may state at once that the anti- 
ferment reaction is to be observed in roots rotating on the klinostat with- 
out undergoing any curvature. This is the only case where the anti- 
ferment reaction occurs (according with the general view) without geotropic 
or analogous induction. But since in other cases we find the anti-ferment 
reaction strictly connected with tropistic induction we may be right, sup- 
posing that geotropic stimulus occurs even in plants rotating on the 
klinostat ; since no curvature takes place, it was hitherto impossible to 
demonstrate this effect directly. But the anti-ferment test is able to show 
it easily and certainly, while the phenomena of grass haulms (Elfving ( 16 ), 
Noll ( 17 )) and pegs or heels of Cucurbita seedlings (Francis Darwin ( 18 ), 
Noll) have established similar conclusions in isolated cases. The facts and 
views recently published by Francis Darwin and Miss Dorothea Pertz ( 19 ), 
which are thoroughly confirmed by the chemical method, are of the highest 
interest in reference to the results mentioned above. 
Several lots of seventy-five seedlings each ( Lupinus albus ) were placed 
in a box made of zinc-plate filled with sawdust, and fastened to the axis of 
the klinostat (Pfeffer-Albrecht model). The lot B was kept in rotation 
for fourteen minutes, the period of revolution being twenty-seven minutes, 
it made therefore half a revolution ; lot C rotated for fourteen minutes with 
a period of revolution of fourteen minutes, i. e. C made a whole revolution. 
