168 TENDRIL-BEARERS. Cuar. IV. 
the twisting of the axis in the one direction is exactly 
compensated by the twisting in the opposite direction. 
We can further see how the tendency is given to make 
the later formed coils opposite to those, whether turned 
to the right or to the left, which are first made. Take 
a piece of string, and let it hang down with the lower 
end fixed to the floor; then wind the upper end 
(holding the string quite loosely) spirally round a per- 
pendicular pencil, and this will twist the lower part of 
the string ; and after it has been sufficiently twisted, it 
will be seen to curve itself into an open spire, with the 
curves running in an opposite direction to those round 
the pencil, and consequently with a straight piece of 
string between the opposed spires. In short, we have 
given to the string the regular spiral arrangement of a 
tendril caught at both ends. The spiral contraction 
generally begins at the extremity which has clasped a 
support; and these first-formed spires give a twist to the 
axis of the tendril, which necessarily inclines the basal 
part into an opposite spiral curvature. I cannot resist - 
giving one other illustration, though superfluous: 
when a haberdasher winds up ribbon for a customer, 
he does not wind it into a single coil; for, if he did, 
the ribbon would twist itself as many times as there 
were coils; but he winds it into a figure of eight on 
his thumb and little finger, so that he alternately 
takes turns in opposite directions, and thus the ribbon 
is not twisted. So it is with tendrils, with this sole 
difference, that they take several consecutive turns in 
one direction and then the same number in an opposite 
