180 TENDEIL-BEAEEKS. Chap. W. 



these movements — cuxTature from a touch. — is thus 

 caused.* In the first place it may be remarked that the 

 movement of nutation differs from that due to a touch, 

 in so far that in some cases the two powers are acquired 

 by the same tendril at different periods of growth; 

 and the sensitive part of the tendril does not seem 

 capable of nutation. One of my chief reasons for doubt- 

 ing whether the curvature from a touch is the result 

 of growth, is the extraordinary rapidity of the move- 

 ment. I have seen the extremity of a tendril of 

 Passiflora gracilis, after being touched, distinctly bent 

 in 25 seconds, and often in 30 seconds ; and so it is 

 with the thicker tendril of Sicyos. It appears hardly 

 credible that their outer surfaces could have actually 

 grown in length, which implies a permanent modifica- 

 tion of structure, in so short a time. The growth, 

 moreover, on this view miist be considerable, for if the 

 touch has been at all rough the extremity is coiled 

 in two or three minutes into a spire of several turns. 



When the extreme tip of the tendril of Echinocystis 

 caught hold of a smooth stick, it coiled itself in a 

 few hours (as described at p. 132) twice or thrice round 



* It occurred to me that the Mis, hut I succeeded only in ob- 



movement of nutation and that serving that both movements were 



from a touch might be differently unaffected by exposure for 1 J hrs. 



affected by anaesthetics, in the to a rather large dose of sulphu- 



sarae manner as Paul Bert has rio ether. In this respect they 



shown to be the case with the present a wonderful contrast with 



sleep-movements of Mimosa and Drosera, owing no doubt to the 



those from a touch. I tried the presence of absorbent glands in 



common pea and Fatsiflora gra- the latter plant. 



