54 



MK. DARWIN OK CLIMBING PLANTS. 



Not 



these petioles, however, are not In the least sensitive. Thus the 

 young internodes, the petioles, and the tendrils, all at the same 

 time, go on revolving together, but at different rates. Moreover, 

 the movements of the opposite petioles and tendrils are quite 

 independent of each other. Hence, when the whole shoot is 

 allowed freely to revolve, nothing can bo more intricate than 



tendril. A 



Wide hemisphere above the shoot is irregularly searched for some 



grasped 



One other curious point remains to be mentioned. Some few 

 days after the toes have closely clasped a stick, their blunt extre- 

 mities become, though not invariably, developed into irregular 

 disk-like balls, which have the singular power of adhering firmly 

 to the wood. As similar cellular outgrowths will be fully de- 

 scribed under B. capreolata, I will here say nothing more about 



them. 



Bignonia ceg^uinoctiaUs, var. Chamlerlai/nii.— The internodes, 

 the elongated non-sensitive petioles, and the tendrHs all have the 

 power of revolviug. The stem does not twine, but ascends a ver- 

 tical stick in the same manner as the last species. The tendrils 

 resemble those of the last species, but are shorter ; the three 

 toes are more unequal in length, two of them being about one- 

 third shorter, and rather thinner than the third ; but they vary 

 m these respects. They terminate in small hard points; and 

 what is important, they do not develope cellular adhesive disks. 

 The reduced size of two of the toes, and their lessened seusitive- 

 ness, seem to indicate a tendency to their abortion ; and the first- 

 formed tendrils on one of my plants were sometimes quite simple. 

 We are thus naturally led to the three following species with 



tendrils 



Bignonia speeiosa.— The young shoots revolve irregulai'ly, 

 making narrow ellipses, or spires or circles, at rates varying from 

 3h. 30 m. to 4 h. 40 m. ; but the plant shows no tendency to twine. 



^ o — J support it does not 

 produce tendrils. The tendrils of a rather young plant were five 

 inches m length ; they revolve spontaneously, as do the short 

 and not sensitive petioles. The tendrils, when rubbed, slowly 

 bend to the rubbed side, and subsequently straighten themselves ; 

 but they are not highly sensitive. There is something strange in 

 their action : I repeatedly placed upright, thick and thin, rougb 

 and smooth sticks and posts, and string suspended vertically, near 



