10 
HOW 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seen, and only as light is given or withdrawn ; 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, however, 
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 
more or less of a circuit. It is not set in 
motion by a touch, but begins, goes on, or 
stops 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 by 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 
Fig. 2. Desmodium gyrans. 
