XXVI.— MECHANOTROPISM: TWINING OF TENDRILS 



By 



Sir J. C. BoSE, 

 Assisted hi/ 



GURUPRASANNA DAS. 



In response to the stimulus of contact a tendril twines 

 round its support. Certain tendrils are uniformly sensitive 

 on all sides ; but in other cases, as in the tendril of 

 Passiflora, the sensitiveness is greater on the under side. 

 A curvature is induced when this side is rubbed with a 

 splinter of wood, the stimulated under side becoming 

 concave. This movement may be distinguished as a move- 

 ment of curling. There is, as I shall presently show, a 

 response where the under side becomes convex, and the 

 curvature becomes reversed. 



As regards perception of mechanical stimulus, Pfeffer 

 discovered tactile pits in the tendrils Cucurhitacece. These 

 pits no doubt facilitate sudden deformation of the sensi- 

 tive protoplasm by frictional contact. No satisfactory ex- 

 planation has however been offered as regards the physio- 

 logical machinery of responsive movement. The difficulty 



