16 PHENOMENA OF PLANT-LIFE. 



in a most marvellous manner. When a revolving branch has 

 found a support, it contracts so as to bring its extremities in 

 contact with it. The other branches seek the same object, 

 and, as they are sensitive on all sides, they fail in many cases 

 to secure a firm attachment with their claws. They therefore 

 detach themselves from their support, one at a time in suc- 

 cession, twist so as to bring their claws into the proper direc- 

 tion, and then again make fast. 



It is well known that most plants grow toward the 

 strongest light ; but climbing plants are sometimes excep- 

 tions. English ivy turns its young shoots away from the 

 light in order that they may come in contact with dark 

 objects, such as rocks and trunks of trees, to which they 

 then attach themselves by short roots. The tendrils of the 

 Virginia creeper, or woodbine, are among the most wonder- 

 ful. They grow away from the light, and send their branches 

 into crevices of old bark and rocks. Sometimes such tendrils 

 are said by Mr. Darwin to actually show a power of choosing 

 one place of attachment in preference to another, by penetrat- 

 ing a cavity and then withdrawing to seek a more satisfactory 

 one. As soon as the tendrils of the creeper find a support, 

 the branches spread out their tips and press them against it. 

 Little pads of hard cellular tissue are now developed at the 

 points of contact, and the tendril coils on itself and becomes 

 very tough and 'woody. At the end of the first season it 

 dies, but remains firmly fixed to its support for many years. 

 Mr. Darwin found one, which, though ten years old, was not 

 detached by a weight of ten pounds from the wall to which it 

 had adhered. 



The chemical constitution of the squash-vine under obser- 

 vation has not yet been determined ; but its anatomical 

 structure, in all its parts, may be readily understood by an 

 examination of the figures appended to this paper, which are 

 accompanied by detailed explanations. The vine, the petioles, 

 the flower-stalks, the tendrils and the fruits were hollow, so 

 that about thirty per cent, of the apparent size was simply 

 air. The greater proportion of the remainder was water, so 

 that less than ten per cent, of the entire volume was solid, 

 dry material. The large, yellow flowers were arranged in 

 regular succession, one at each node. A female flower was 



