MOTIONS IN PLANTS. 
2G9 
found next the alburnum, by which means they are more laid 
open to the influence of the seasons, and the perpetual changes 
of the atmosphere : this, probably, would be too exposed a situa- Different 
for the winter, but causes the vegetable tribe to be more easily *'tua'>onoftfce- 
. . . ^ »pirat. 
moved and acted upon in summer, autumn, or spring ; in all 
plants whatever, the spiral wire, when rising from the root, as 
soon as it arrives at a branch, detaches a number of these mus- 
cles, and they divide and run up each leaf and flower branch, 
and the quantity is admirably adapted to the size of the leaf it 
lifts and governs — as in the cabbage leaf, they are in sets as 
thick as a packthread, and have not only great strength, but 
art adds much to their force, for they are most admirably 
looped and twisted to support and catch each other, at:d curi- 
ously balanced in power, and fixed by means of those little 
green balls under which the spiral appears to run, and round 
which they are often wound, with many a slip knot. 
If the large leaves of the arctium lappa are examined, and 
their mid-ribs dissected, it will plainly appear that the spiral 
runs by impulses} which, when much agitated, seems to draw 
.and stop like the moment-hand of a watch. But this is only 
when a storm or quick changes of the atmosphere produce vio- 
lent agitation ; then the motion is indeed excessive, and in Convnhinn* 
° ’ . ofthespiia* 
starts } this has been observed by many in the mimosa sensitiva, wire, 
for when the leaves are made to change their position it is 
always with a jerk — and the knots formed in most spiral wire 
•admirably accounts for this — indeed the motion of vegetables is 
>a!l of this kind, tliough in a greater or lesser degree, according 
to the number of balls and knots they possess. This is only to 
Be known by those who will take the trouble acutely to observa 
and watch plants } but is best seen if the spirals are taken out of 
their cases, and exposed naked to the atmosphere : then they 
vCan be compared only to a riggling worm, and the spiral woufd 
‘be taken for one if placed where the air could reach it } it is 
really beautiful, if along piece isobt.aincd, to see it wind and start 
• as the various insensible changes of the atmosphere aflect it } it 
•will be asked, as they are insensible, how I know it is that cause 
•which acts } 1 can know it only by observing how excessive ia 
the 
