18 DROSERA ROTUNDIFOLIA. [Chap. II. 



CHAPTER II. 



THE MOVEMENTS OF 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 thenj 

 Difli'rence 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 com- 

 mencing inflection and of subsequent re-expansion Extreme minute- 

 ness of the particles causing inflection Action under water Inflec- 

 tion 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 vari- 

 ous ways. The glands alone in all ordinary cases are sus- 

 ceptible 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 sensitive 

 generally implies consciousness ; but no one supposes 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 tenta- 

 cles 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 exterior tentacles, 

 near their bases, and does not (as will hereafter be proved) 

 first travel up the pedicels to the glands, to be then reflected 

 back to the bending place. Nevertheless, some influence does 

 travel up to the glands, causing them to secrete more copious- 

 ly, and the secretion to become acid. This latter fact is, I 

 believe, quite new in the physiology of plants; it has indeed 

 only recently been established that in the animal kingdom an 



