CHAP. X. DIRECTION OF INFLECTED TENTACLES. 245 



plan is to place a particle of the phosphate of lime 

 moistened with saliva on a single gland on one side 

 of the disc of a large leaf, and another particle on a 

 single gland on the opposite side. In four such 

 trials the excitement was not sufficient to affect the 

 outer tentacles, but all those near the two points 

 were directed to them, so that two wheels were formed 

 on the disc of the same leaf ; the pedicels of the 

 tentacles forming the spokes, and the glands united 

 in a mass over the phosphate representing the axles. 

 The precision with which each tentacle pointed to 

 the particle was wonderful ; so that in some cases I 

 could detect no deviation from perfect accuracy. 

 Thus, although the short tentacles in the middle of 

 the disc do not bend when their glands are excited 

 in a direct manner, yet if they receive a motor impulse 

 from a point on one side, they direct themselves to the 

 point equally well with the tentacles on the borders of 

 the disc. 



In these experiments, some of the short tentacles on 

 the disc, which would have been directed to the centre, 

 had the leaf been immersed in an exciting fluid, were 

 now inflected in an exactly opposite direction, viz. 

 towards the circumference. These tentacles, therefore, 

 had deviated as much as 180 from the direction which 

 they would have assumed if their own glands had 

 been stimulated, and which may be considered as the 

 normal one. Between this, the greatest possible and no 

 deviation from the normal direction, every degree could 

 be observed in the tentacles on these several leaves. 

 Notwithstanding the precision with which the tentacles 

 generally were directed, those near the circumference 

 of one leaf were not accurately directed towards some 

 phosphate of lime at a rather distant point on the 

 opposite side of the disc. It appeared as if the motor 



