THE PLANT IN ACTION. 263 



to secure the fertilization of the pistil from the pollen 

 of its own flower. But this is not so. The move- 

 ment takes place when an insect, in quest of the 

 honey in the glands at the base of the pistil, touches 

 the inside of one of the stamens. The pollen is thus 

 thrown on the insect, which conveys it to the next 

 flower it visits, and, leaving some of it on the stigma, 

 brings about cross-fertilization. 



Interesting motions, dependent upon contact, are 

 also seen in the tendrils of many climbing plants, 

 which bend and alter the position at the touch. 



CLIMBING PLANTS. These are of various kinds, and 

 are so common as to be easily found by anybody who 

 will look out for them. When a plant is seen to be- 

 long to this class, the first question, to be considered 

 is, How does it climb upon its support ? Does it twist 

 around it (twining) ? Does it put out fingers, roots, 

 or suckers, for attachment (root-climbers) ? or does it 

 shoot out tendrils (tendril-climbers)? The tendrils 

 of climbing plants exhibit interesting motions, de- 

 pendent upon contact. They bend, and alter their 

 position at the touch. This curling effect, which en- 

 sues from contact, is represented in Fig. 419. The 

 motion consequent on a single touch increases for a 

 time, then ceases, and, after a few hours, the tendril 

 uncurls, and resumes its former position. Tendrils 

 have a tendency to curl round any object with which 

 they come into contact, except other tendrils of the 

 same plant. It has been remarked as curious that, in 

 some exceedingly sensitive plants, the falling of drops 

 of rain on the tendril produces no movement. Ten- 

 drils are contrivances for climbing ; they stretch out 



in search of support, and move through circuits to 

 12 



