1903.] 



The Statolith-theory of Geotropism. 



373 



In three of the experiments (102, 109, 111) readings were taken 

 before the plants were placed on the klinostat, and these readings are 

 omitted in summing up the results : — 



Curvature of shaken plants greater... 7 cases 



still ,, ,, ... 4 

 Shaken, equal still 1 



Thus there is a majority of wins in favour of the shaken plants, 

 though it is not nearly so striking as in the geotropic experiments. 

 When the amount of curvature is taken into consideration, the result 



is decisive : — 



Still. Shaken. 



Sum of averages 259-9 273-9 



or as 100 105*4 



The conclusion at which I arrive is that vibration does not 

 materially increase heliotropic curvature, whereas it does increase 

 geotropism. The following figures show in round numbers the differ- 

 ence between the geotropic and heliotropic experiments : — 



Geotropic Curvature. 



Still. Shaken. 

 100 144 



Heliotropic Curvature. 



Still. Shaken. 

 100 105 



The inference I draw from this result is the same as that of Haberlandt, 

 viz., that the increased geotropism of the shaken specimens is due to 

 the increased stimulus produced by the vibration of the starch grains 

 on the protoplasm of the lateral walls of the cells. 



I desire to express my thanks to Miss Pertz, and to my assistant 

 Mr. Elborn, for much valuable help. 



