290 



LIFE MOVEMENTS IN PLANTS 



have in this investigation studied the effect not merely of 

 mechanical, but also of other forms of stimuli. I shall also 

 describe the diverse effects induced by mechanical st mulus 

 under different conditions. From the results of these experi- 

 ments I shall be able to show that the twining of the tendril 

 comes under the general law of tropic curvature ; that 

 the curvature results from the contraction of the proximal 

 and expansion of the distal side. Finally I shall be able 

 to offer a satisfactory explanation of the inhibition of 

 response of the tendril by the stimulation of the opposite 

 side of the organ. 



OENERAL EFFECTS OF INDIRECT AND DIRECT ELECTRIC 

 STIMULATION ON THE GROWTH OF TENDRIL. 



For this experiment I took a growing tendril of 

 Cucurbita in which the sensitiveness is 

 more or less uniform on all sides. The 

 tendril was suitably mounted on the 

 Balanced Cresnograph, which records the 

 variation of the rate of growth induced 

 by immediate and after-effect of 

 stimulus. The specimen is held in a 

 clamp as in the diagram (Fig. 102), 

 the tip being suitably attached to the 

 recording lever. For indirect stimulation 

 feeble shock from an induction coil is 

 applied at the two electric connections 

 Fi«. io-2.-i)iagramn,atic below the damp. Direct stimulus is 

 repiedentation of indirect applied by means of electric connections 

 and direct stimulation of ^^^ above and the Other below the 



clamp. 



tendril 



