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THE POPULAR SCIENCE MONTHLY. 



when climbing. When a climbing plant first springs from the ground, 

 the extremity of the shoot performs slow gyrations in the air, as if, as 

 Darwin expresses it, it were searching for a support. I do not here 

 discuss the question whether this habit may be the result of a tendency 

 transmitted and enhanced through thousands of generations ; the move- 

 ment itself is, in the individual plant, entirely " spontaneous," in every 

 sense of the term ; that is, is not the necessary result of known physi- 

 cal laws acting upon the individual. Darwin's paper, " On the Move- 

 ments and Habits of Climbing Plants," published in the Journal of the 

 Linnoean Society, contains a number of the most interesting observa- 

 tions on this class of plants ; and the language employed is everywhere 

 suggestive of some hidden, sentient controlling power in the plant it- 

 self. 



Fis. 3. 



The same purpose as that served by a climbing stem is answered in 

 other plants, as the vine, Virginian creeper, and passion-flower, by ten- 

 drils ; and the phenomena of spontaneous motion in tendrils are, if 

 possible, still more curious. Some tendrils display the same power of 

 rotatory motion possessed by the extremities of the shoots of climbing 

 plants ; others do not revolve, but are sensitive, bending to the touch. 

 The curling movement, consequent on a single touch, continues to in- 

 crease for a considerable time, then ceases ; after a few hours the ten- 

 dril uncurls itself, and is again ready for action. A tendril will thus 

 J show a tendency to curl round any object with which it comes into 

 contact, with the singular exception that it will seldom twine itself 

 round another tendril of the same plant. It is also very curious that, 



