1904.] Notes on the Statolith Theory of Geotropism. 481 



slight. But the existence of a considerable number of apically-cornered 

 cells can, we think, only be accounted for as the result of centrifugal 

 force. Without centrifugal force the starch should have been lateral 

 or basally cornered. 



In the remaining experiments (Table IV) two sets of seedlings were 

 used one with the apices radially outwards, the other radially inward. 

 Here the result was more decided. 



Table IV. 



Plant. 



Centrifugal 

 force. 



Temp. 



Apex of 

 seedling. 



Position of starch. 





g- 



°C. 







Setaria and 



0-03 



18 



Out V 



Scattered and lateral ; a few 



Sorghum 







In } 



apical in both. 





0-03 



16 



Out 



Apically cornered and scat- 











tered. 









In 



Basal. 





0-04 



20 



Out 



Apical and lateral. 









In 



Basal. 





0-06 



20 



Out 



Apical, lateral; some basal. 









In 



Basal, scattered. 



Sorghum .... 



0-07 



17 -5—20 



Out 



Scattered, apical. 







In 



Basal. 



It is clear from these results that a force of 0-03 — 0*04 g. has 

 a distinct effect on the position of the starch grains. The effect of 

 0'06 and 0'07 g. was not materially greater than that of 004, and we 

 are inclined to think that this is also true in the experiments with a 

 horizontal axis of rotation. 



Inclined Plane. — We made a few experiments, in which seedlings 

 were fixed on plane surfaces inclined at angles varying from 2 — 5°. 

 If the plane be inclined at an angle 6, the component of gravity acting 

 in the line of the plane will be sin g. Thus, if the seedlings be 

 placed apex downwards, on a plane inclined at 2°, there will be a force 

 equal to 0'035 g., tending to move the starch grains to the apices of the 

 cells. Our experiments were not very numerous, but, as far as they 

 go, they confirm the above results. We find that the statoliths are 

 displaced by - 035g., but not by 0'017 g. 



The Behaviour of the Statoliths on the Klinostat. — When a plant is kept 

 slowly rotating on a horizontal axis, the practical result is that it does 

 not bend geotropically. The result has been explained by the suppo- 

 sition that the plant never remains in one position long enough for 

 the perception of gravity. But there are experiments which show 

 that (at any rate, in certain cases) the gravitational stimulus is con- 

 tinuously perceived, but fails to produce a curvature, because of its 



