OIIAP. II. INFLECTION INDIRECTLY CAUSED. 19 



CHAPTEE II. 



THE MOVEMENTS OP THE TENTACLES FROM THE CONTACT OF SOLID 



BODIES. 



Inflection of the exterior tentacles owing to the glands of the disc 

 being excited by repeated touches, or by objects left in contact 

 with them Difference in the action of bodies yielding and not 

 yielding soluble nitrogenous matter Inflection of the exterior 

 tentacles directly caused by objects left in contact with their 

 glands Periods of commencing inflection and of subsequent re- 

 expansion Extreme minuteness of the particles causing inflection 

 Action under water Inflection of the exterior tentacles when 

 their glands are excited by repeated touches Falling drops of 

 water do not cause inflection. 



I WILL give in this and the following chapters some of 

 the many experiments made, which best illustrate the 

 manner and rate of movement of the tentacles, when 

 excited in various ways. The glands alone in all 

 ordinary cases are susceptible to excitement. When 

 excited, they do not themselves move or change form, 

 but transmit a motor impulse to the bending part of 

 their own and adjoining tentacles, and are thus carried 

 towards the centre of the leaf. Strictly speaking, the 

 glands ought to be called irritable, as the term sensi- 

 tive generally implies consciousness ; but no one sup- 

 poses that the Sensitive-plant is conscious, and as I 

 have found the term convenient, I shall use it without 

 scruple. I will commence with the movements of the 

 exterior tentacles, when indirectly excited by stimulants 

 applied to the glands of the short tentacles on the disc. 

 The exterior tentacles may be said in this case to be 

 indirectly excited, because their own glands are not 

 directly acted on. The stimulus proceeding from the 

 glands of the disc acts on the bending part of the 



