SPIRAL TWINERS. 21 



and then in the opposite direction ; consequently, when I placed 

 the shoots near thin or thick sticks, or stretched string, they 

 seemed perpetually to be trying to ascend these supports, but 

 failed. I then surrounded the plant with a mass of branched 

 twigs ; the shoots ascended, and passed through them, but 

 several came out laterally, and their depending extremities sel- 

 dom turned upwards as is usual with twining plants. Finally, 

 I surrounded another plant with many thin upright sticks, and 

 placed this plant near the other plant with the twigs ; and now 

 the Hibbertia had got what it liked, for it twined up the parallel 

 sticks, sometimes winding round one and sometimes round several ; 

 and the shoots travelled laterally from one to the other plant ; 

 but as the plants grew older, some of the shoots twined regularly 

 up a thin upright stick. Though the revolving movement was 

 sometimes in one direction and sometimes in the other, the twi- 

 ning was invariably from left to right ; so that the more potent: 

 or persistent movement of revolution must have been in oppo- 

 sition to the course of the sun. It would appear that this Hib- 

 bertia is adapted to ascend by twining, and to ramble laterally over 

 the thick Australian scrub. 



I have described this case in some detail, because, as far as I 

 have seen, it is rare to find with twining plants any especial 

 adaptations, in which respect they differ much from the more 

 highly organized tendril-bearers. The Solatium dulcamara, as we 

 shall presently see, can twine only round such stems as are both 

 thin and flexible. Most twining plants apparently are adapted 

 to ascend supports of different thicknesses. Our English twiners, 

 as far as I have seen, never twine round trees, excepting the 

 Honeysuckle (Lonicera periclymemtm), which I have observed 

 twining up a young beech-tree nearly 4£ inches in diameter. 

 Mohl (S. 131) found that the Phaseolus multiflorus and Ipomcea 

 purpurea could not, when placed in a room with the light entering 

 on one side, twine round sticks between 3 and 4 inches in dia- 

 meter ; for this interfered, in a manner presently to be explained, 

 with the revolving movement. In the open air, however, the 

 Phaseolus twined round a support of the above thickness, but- 

 failed in twining round one 9 inches in diameter. Nevertheless, 

 some twiners of the warmer temperate regions can manage this 

 latter degree of thickness ; for I hear from Dr. Hooker that at 

 Kew the Ruscus androgi/nm ascends a column 9 inches in dia- 

 meter ; and although ^Wistaria grown by me in a small pot tried in 

 vain for weeks to get round a post between 6 and G inches in 



