TENDIUL-BEAREKS. 



09 



Via. 7. 



modified lateral leaflets ; but Mold (S. 41) ranks them as modified 

 stipules. These tendrils are from 1| to 1| inch in length, are thin, 

 and have slightly curved, pointed extremities. They diverge a 

 little from each other, but stand at first nearly upright. When 

 lightly rubbed on either side, they slowly bend to that side, and 

 subsequently become straight again. The back or convex side of a 

 tendril placed in contact with a stick became just perceptibly 

 curved in Hi. 20m., but did not completely surround the stick till 

 48h. had elapsed ; the con- 

 cave side of another tendril 

 became considerably curved 

 in 2 h., and fairly clasped the 

 stick in 5 h. As the tendrils 

 grow old, they diverge more 

 from each other and slowly 

 bend towards the stem and 

 downwards, so that they 

 project on the opposite side 

 of the stem to that on which 

 they arise ; they still retain 

 their sensitiveness, and can 

 clasp a support placed be- 

 hind the stem. Owing to 

 this movement, the plant 

 can ascend a thin upright 

 stick, clasping it with the 

 tendrils which arise from 

 the leaves placed alternately 

 on opposite sides of the 

 stem. Ultimately the two 

 tendrils belonging to the 



Smilax aspcra. 



same petiole, if they do not come into contact with any object, 

 cross each other (as at B in fig. 7) behind the stem and loosely 

 clasp it. This movement of the tendrils towards and round the 

 stem is, to a certain extent, guided by the action of the light ; 

 for when the plant stood so that one of the two tendrils in 

 thus slowly moving had to travel towards the light, and the other 

 from the light, the latter always travelled, as I repeatedly ob- 

 served, more quickly than its fellow. The tendrils do not con- 

 tract 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 is guided, to 



