4 DARWINISM STATED BY DARWIN HIMSELF. 



after a mere temporary curvature, contract spirally. If 

 they have not come into contact with any object, they 

 ultimately contract spirally, after ceasing to revolve ; but 

 in this case the movement is useless, and occurs only after 

 a considerable lapse of time. 



With respect to the means by which these various 

 movements are effected, there can be little doubt, from 

 the researches of Sachs and H. de Vries, that they are 

 due to unequal growth ; but, from the reasons already 

 assigned, I can not believe that this explanation applies to 

 the rapid movements from a delicate touch. 



Finally, climbing plants are sufficiently numerous to 

 form a conspicuous feature in the vegetable kingdom, 

 more especially in tropical forests. America, which so 

 abounds with arboreal animals, as Mr. Bates remarks, 

 likewise abounds, according to Mohl and Palm, with 

 climbing plants ; and, of the tendril-bearing plants exam- 

 ined by me, the highest developed kinds are natives of 

 this grand continent, namely, the several species of Big- 

 nonia, Eccremocarpus, Cobcea, and Ampelopsis. But even 

 in the thickets of our temperate regions the number of 

 climbing species and individuals is considerable, as will 

 be found by counting them. 



THE POWEK OF MOVEMENT IN ANIMAL AND PLANT 

 COMPARED. 



It has often been vaguely asserted that 

 plants are distinguished from animals by not 

 having the power of movement. It should rather be said 

 that plants acquire and display this power only when it is 

 of some advantage to them ; this being of comparatively 

 rare occurrence, as they are affixed to the ground, and 

 food is brought to them by the air and rain. We see 

 how high in the scale of organization a plant may rise, 



