Chap. X. TRANSMISSION OF MOTOR IMPULSE. 235 



the exterior tentacles to bend until half an hour or 

 even several hours have elapsed. 



The motor impulse spreads gradually on all sides 

 from one or more excited glands, so that the ten- 

 tacles which stand nearest are always first affected. 

 Hence, when the glands in the centre of the disc 

 are excited, the extreme marginal tentacles are the 

 last inflected. But the glands on different parts of 

 the leaf transmit their motor power in a somewhat 

 different manner. If a bit of meat be placed on 

 the long-headed gland of a marginal tentacle, it 

 quickly transmits an impulse to its own bending 

 portion ; but never, as far as I have observed, to the 

 adjoining tentacles; for these are not affected until 

 the meat has been carried to the central glands, 

 which then radiate forth their conjoint impulse on all 

 sides. On four occasions leaves were prepared by 

 removing some days previously all the glands from 

 the centre, so that these could not be excited by 

 the bits of meat brought to them by the inflection of 

 the marginal tentacles ; and now these marginal ten- 

 tacles re-expanded after a time without any other 

 tentacle being affected. Other leaves were similarly 

 prepared, and bits of meat were placed on the 

 glands of two tentacles in the third row from the out- 

 side, and on the glands of two tentacles in the fifth 

 row. In these four cases the impulse was sent 

 in the first place laterally, that is, in the same 

 concentric row of tentacles, and then towards the 

 centre; but not centrifugally, or towards the ex- 

 terior tentacles. In one of these cases only a single 

 tentacle on each side of the one with meat was 

 affected. In the three other cases, from half a dozen 

 to a dozen tentacles, both laterally and towards the 

 centre, were well inflected or sub-inflected. Lastly, in 



