Stimulation and Correlation. 115 



125. Perceptive region in leaves of grasses. Grow 

 a number of seedlings of oats or wheat or canary grass 



\ 



Fig. 84. Positions assumed by blades of leaves of mallow. The arrows denote 

 direction of rays of light. 



(Phalaris] in a shallow dish of moist soil or sawdust. Make 

 several cylinders of tin-foil of sufficient size to fit snugly over 

 the leaves. To do this, wrap a strip of tin-foil round a match 



