10 



now PLANTS MOVE, CLIMB, 



easy to cultivate in a hot-house, or even in an open garden during the heat of 

 summer. The leaves are of only three leaflets (Fig. 2), a large one at the end 

 of the leafstalk, accompanied by a pair of small leaflets, one on each side. The 



end leaflet usually moves too slowly to be 

 seen, and only as light is given or withdrawn ; 

 we have seen it move rather briskly, ho\vever, 

 upon one occasion. The side leaflets are 

 active enough. Under the temperature of a 

 sultry summer's day they may be seen to rise 

 and fall by a succession of jerking move- 

 ments, not unlike those of the second-hand 

 of a clock, but without much regularity, now 

 stopping for some time, then moving briskly, 

 always resting for a while in some part of 

 their course, commonly at the highest and 

 lowest points, and starting again without ap- 

 parent cause, seemingly of their own will. 

 The movement is not simply up and down, 

 but the end of the moving leaflet sweeps 

 iriore or less of a circuit. It is not set in 

 'notion by a touch, but begins, goes on, or 

 -tops of itself. 



4. Whether these movements are of any 

 use to these plants is more than we can tell ; 

 nor do we very well know how they are ef- 

 fected. The attempts that have been made to explain how the motion is brought 

 about need not be considered here. However done, it is clear that the leaves 

 'move hy their own act, — in the one case responding to a touch ; in the other 

 independently, or, as we say, spontaneously. 



5. Now, truly wonderful as these two plants are, there is nothing really pecu- 

 liar about them. By which is meant, not merely that some other plants are 

 known to move as freely, though perhaps less rapidly, but that many ordinary 

 plants perform similar movements, in one or both of these ways, and that all 

 plants possess similar faculties. The hour-hand of the clock moves as really as 

 the minute-hand and the second-hand, although the motion of the latter only is 



Tig. 2. Desmodium gyrans. 



