22 



those on the opposite side. The pnlvini are cross-grooved, the 

 furrows assisting the bending by permitting compression and 

 expansion the more easily. A very deep groove is located at the 

 point of convergence of the vascular bundles. A deepening of 

 the smaller furrows, together with an increase in their number, 

 occurs on the side that is compressed. A consequent smoothing 

 out process is apparent on the opposite side. * 



Figure 10. — Camera lucida drawings of the cortex on opposite sides of a 

 pulvinus from a leaf in the "sleep" position. The upper figure is from 

 the convex side. 



