THE MOVEMENTS AND HABITS OF PLANTS. 3 



secluded from the light. The guiding stimulus no doubt 

 is the attraction of gravity, as Andrew Knight showed to 

 be the case with germinating plants. If a shoot of any 

 ordinary plant be placed in an inclined position in a glass 

 of water in the dark, the extremity will, in a few hours, 

 bend upward ; and, if the position of the shoot be then 

 reversed, the downward-bent shoot reverses its curvature ; 

 but if the stolon of a strawberry, which has no tendency 

 to grow upward, be thus treated, it will curve downward 

 in the direction of, instead of in opposition to, the force 

 of gravity. As with the strawberry, so it is generally with 

 the twining shoots of the Hibbertia dentata, which climbs 

 laterally from bush to bush ; for these shoots, if placed 

 in a position inclined downward, show little and some- 

 times no tendency to curve upward. 



3. Climbing plants, like other plants, bend toward 

 the light by a movement closely analogous to the incurv- 

 ation which causes them to revolve, so that their revolv- 

 ing movement is often accelerated or retarded in travel- 

 ing to or from the light. On the other hand, in a few 

 instances tendrils bend toward the dark. 



4. We have the spontaneous revolving movement 

 which is independent of any outward stimulus, but is 

 contingent on the youth of the part, and on vigorous 

 health ; and this again, of course, depends on a proper 

 temperature and other favorable conditions of life. 



5. Tendrils, whatever their homological nature may 

 be, and the petioles or tips of the leaves of leaf -climbers, 

 and apparently certain roots, all have the power of move- 

 ment when touched, and bend quickly toward the touched 

 side. Extremely slight pressure often suffices. If the 

 pressure be not permanent, the part in question straight- 

 ens itself and is again ready to bend on being touched. 



6. Tendrils, soon after clasping a support, but not 



