120 TENDRIL-BEARERS. Chap. 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 light ; 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 8 feet in height, that the stem 

 is zigzag and is furnished, as well as the petioles, with 



