208 



PLANT LIFE. 



normally expanded is shown in figure 206, and their position 

 after stimulation by figure 207. The stamens (^[ 344) of 

 some flowers and the stigmas (^j 336) of others are sensitive 



FIG. 206. FIG. 207. 



FIG. 205. Part of a transverse section of a leaf of Venus' fly-trap, in, the cushion of 

 tissue constituting the motor organ ; b, one of the sensitive bristles which, upon being 

 touched, cause the leaf to close ; t, one of the interlocking teeth. The minute pro- 

 jections over inner (ventral) surface are glands which secrete the digestive fluid and 

 later absorb the food. Magnified about 5 diam. After Kurz. 



FIG. 206. A leaf of the sensitive plant fully expanded. Natural size. After Duchartre. 



FIG. 207. A leaf of the sensitive plant after stimulation. The motor organ at the base 

 of each leaflet has thrown it forward and upward ; the motor organs at the base of the 

 four divisions have moved them together. The motor organ at the base of the main 

 petiole has moved the whole leaf sharply downward. Natural size. After Duchartre. 



to a touch, shortening, elongating, or bending in such a way 

 as to promote pollination (^[ 358). 



The motor organs of the leaves of a number of the bean 

 and oxalis families also react to more violent mechanical 

 stimuli. Their movements are similar to those described in 



H 



