120 TENDRIL-BEARERS. Cuap. III. 
* 
of the stem to that from which they arise. They then 
still retain their sensitiveness, and can clasp a support 
placed behind the stem. Owing to this power, the 
plant is able to ascend a thin upright stick. Ulti- 
mately the two tendrils belonging to the same petiole, 
if they do not come into contact with any object, 
loosely cross each other behind the stem, as at B, in 
fig. 7. This movement of the tendrils towards and 
round the stem is, to a certain extent, guided by their 
avoidance of the ight; for when a plant stood so that 
one of the two tendrils was compelled in thus slowly 
moving to travel towards the light, and the other from 
the light, the latter always moved, as I repeatedly 
observed, more quickly than its fellow. The tendrils 
do not contract spirally in any case. Their chance 
of finding a support depends on the growth of the 
plant, on the wind, and on their own slow backward 
and downward movement, which, as we have just seen, 
is guided, to a certain extent, by the avoidance of the 
light ; for neither the internodes nor the tendrils have 
any proper revolving movement. From this latter 
circumstance, from the slow movements of the tendrils 
after contact (though their sensitiveness is retained for 
an unusual length of time), from their simple structure 
and shortness, this plant is a less perfect climber than 
any other tendril-bearing species observed by me. The 
plant whilst young and only a few inches in height, 
does not produce any tendrils; and considering that 
it grows to only about § feet in height, that the stem 
is zigzag and is furnished, as well as the petioles, with 
