Cause of Motion in Plants. 



361 



opinion, a most curious and unexpected illustration of the 

 theory which I have been attempting to prove. 



Let us now review the jr;« 4. 



facts and experiments which 

 have been adduced, and see 

 what may be reasonably 

 made out from them. 



It has been proved by di- 

 viding the stem of a plant 

 which has already under- 

 gone curvature upwards, 

 (Exp. I. and 2.) that both 

 the segments are endowed 

 with the property of diver- 

 gence. 



It is evident also from the 

 same experiments, that the 

 lower segment cannot con- 

 tribute to this motion, as any 

 effect which it may have 

 must be greatest in an op- 

 posite direction. 



The motion or curvature 

 upwards must therefore de- 

 pend on the other, the upper 

 segment; and when we see 

 the great, the excessive force 

 with which the upper seg- 

 ment retracts on being Fig. 5. 

 freed from the anta- 

 gonism of the lower 

 segment, we can hardly 

 fail to believe, that in 

 this retraction (or rather 

 in its cause) we have 

 discovered an adequate, 

 and I think the true 

 source of the motion. 



Hence, I come to the 

 conclusion, that the kind 

 of motion here treated 

 of is the result of the 

 contractile force or di- 

 vergence of the upper 

 segment prevailing over 

 that of the lower. 



Third Series. Vol. 7. No. 41. Nov. 1835. 



3A 



