The Analysis of Geotropism. 13 
our experiments of 1888 or Czapek’s are really adapted to solve the 
question. It is quite conceivable that in a given time a weak 
stimulus might be able to produce as much curvature as a stronger 
one. Just as a small weight and a bigger weight may both be able 
to fire a gun, and thus produce equal effects though they themselves 
are not equal. 
The method used by Miss Pertz 1 is a much better one, namely 
that of the intermittent klinostat, by means of which apogeotropic 
plants were alternately placed at 45° above and below the horizon. 
The nature of the resulting curvature seemed to show that Czapek 
is right and that —45° is more effective than +45 n . But this result 
must not be trusted owing to an error to which I shall return. Other 
experiments of the same kind were made by Newcombe 2 and by Miss 
Haynes 3 who alternated various angular positions and concluded 
that the horizontal is that of maximum stimulation. Fitting has 
undoubtedly solved the question by a new method of using the 
klinostat, namely by making the axis oblique instead of horizontal. 
Its novelty is not at first apparent, for if the organ is parallel to the 
axis, the oblique klinostat does not differ from the horizontal one. 
The gravitation stimulus will be less than with the horizontal 
klinostat, but it will be evenly distributed about the plant just as 
with the ordinary instrument. But if the plant is not parallel to 
the axis, the result will be different, as will be seen in the 
accompanying diagram. 
Figure illustrating the oblique klinostat. 
If, for example, the axis, kk, of the klinostat is 22^° below the 
horizon, and the plant, p, makes an angle of 22|° with kk, then, 
assuming it to be an intermittent klinostat (which rotates through 
180 n at regular intervals of time), the alternating positions of the 
plant will be p, and p a , i.e., horizontal and—45°. If p x is the 
1 Annals Bot. XIII., 1899, p. 620. Czapek had previously used 
the method for diageotropic roots, see Sitz K. Akad. Wien 
104, 1895. 
2 Annals of Botany, 1905. 
3 American Naturalist, 1905. 
