88 TENDRIL-BEAREKS. Chap. III. 



even a small loop of thread suspended for two days 

 caused it to bend upwards ; but the sub-petioles of 

 the two lateral leaflets are not sensitive. The whole 

 tendril, namely, the tarsus and the three toes, 

 are likewise sensitive to contact, especially on their 

 under surfaces. When a shoot grows in the midst of 

 thin branches, the tendrils are soon brought by the 

 revolving movement of the internodes into contact 

 with them ; and then one toe of the tendril or more, 

 commonly all three, bend, and after several hours seize 

 fast hold of the twigs, like a bird when perched. If 

 the tarsus of the tendril comes into contact with a 

 twig, it goes on slowly bending, until the whole foot 

 is carried quite round, and the toes pass on each side 

 of the tarsus and seize it. In like manner, if the petiole 

 comes into contact with a twig, it bends round, carry- 

 ing the tendril, which then seizes its own petiole or 

 that of the opposite leaf. The petioles move spon- 

 taneously, and thus, when a shoot attempts to twine 

 round an upright stick, those on both sides after a time 

 come into contact with it, and are excited to bend. 

 Ultimately the two petioles clasp the stick in opposite 

 directions, and the foot-like tendrils, seizing on each 

 other or on their own petioles, fasten the stem to the 

 support with surprising security. The tendrils are 

 thus brought into action, if the stem twines round a 

 thin vertical stick ; and in this respect the present 

 species differs from the last. Both species use their 

 tendrils in the same manner when passing through a 

 thicket. This plant is one of the most efficient climbers 



