MOVEMENTS OF IRRITATION'. 



487 



III. THE WINDING OF TENDRILS, 

 AND TWINING PLANTS. 



186. Generalities Respecting the Winding 

 of Twining Plants. 



If we examine a hop stem wound round a 

 support, we shall find that the spiral always 

 runs from right below to left above. The 

 hop is a typical right- winding 1 plant.* It 

 may here also be remarked that both stems 

 and leaf -stalks of hops are provided with 

 peculiarly formed appendages, which func- 

 tion as clinging or clasping organs, since 

 they assist in fixing the plants. If we re- 

 move, e.g., from the leafstalk of Humulus, 

 small strips of epidermis, and examine 

 them microscopically, it will be seen that 

 on the surface are seated wart-shaped 

 emergences. Each of these bears at its 

 end an anchor-shaped hair, which forms an 

 excellent organ of attachment. 



A few flower-pots, not too small, are filled 

 with well- watered garden soil, and soaked 

 seeds of Phaseolus multiflorus are laid in 

 them. It is advisable to put several seeds 

 into each flower-pot, and then later the 

 weakly plants may be removed, and only 

 one vigorous specimen in each pot be further 

 cultivated. It is best to grow the plants 

 in a place where they will be exposed only 

 for a short time in the day to direct sun- 

 light, being for the rest of the day exposed 

 to bright diffuse daylight. When the third 

 internode begins to develop, we place long 

 sticks close to the plants. These wind 



* In botany it is customary to associate with the 

 terms "right" and "left," as applied to spirals, a 

 meaning opposite to that which they have in me- 

 chanics. 



FIG. 163. Winding shoot 

 of Phaseolus multiflorus. 



