Chap. X.] TRANSMISSION OP MOTOR IMPULSE. 193 



the bit of meat lay as did those at the two ends. It thus ap- 

 peared as if the motor impulse was transmitted from the 

 centre across the disc more readily in a longitudinal than in 

 a transverse direction; and as this appeared a new and in- 

 teresting fact in the physiology of plants, thirty-five fresh 

 exi)eriments were made to test its truth. Minute bits of 

 meat were placed on a single gland or on a few glands, on 

 the right or left side of the discs of eighteen leaves; other 

 bits of the same size being placed on the distal or proximal 

 ends of seventeen other leaves. Now if the motor impulse 

 were transmitted with equal force or at an equal rate 

 through the blade in all directions, a bit of meat placed at 

 one side or at one end of the disc ought to affect equally all 

 the tentacles situated at an equal distance from it; but this 

 certainly is not the case. Before giving the general results, 

 it may be well to describe three or four rather unvisual cases, 



(1) A minute fragment of a fly was placed on one side of the 

 disc, and after 32 m. seven of the outer tentacles near the fragment 

 were inflected: after 10 hrs. several more became so, and after 23 

 hrs. a still greater number; and now the blade of the leaf on this 

 side was bent inwards so as to stand up at right angles to the 

 other side. Neither the blade of the leaf nor a single tentacle on 

 the opposite side was aflTected; the line of separation between the 

 two hands extending from the footstalk to the apex. The leaf 

 remained in this state for three days, and on the fourth day be- 

 gan to re-expand; not a single tentacle havii^ been inflected on 

 the opposite side. 



(2) I will here give a case not included in the above thirty- 

 five experiments. A small fly was found adhering by its feet to 

 the left side of the disc. The tentacles on this side soon closed in 

 and killed the fly: and owing probably to its struggle whilst alive, 

 the leaf was so much excited that in about 24 hrs. all the tentacles 

 on the opposite side became inflected; but as they found no prey, 

 for their glands did not reach the fly, they re-expanded in the 

 course of 1.5 hrs.; the tentacles on the left side remaining clasped 

 for several days. 



(3) A bit of meat, rather larger than those commonly used, was 

 placed in a medial line at the basal end of the disc, near the foot- 

 stalk; after 2 hrs. 30 m. some neighbouring tentacles were in- 

 flected ; after 6 hrs. the tentacles on Iwth sides of the footstalk, and 

 some way up both sides, were moderately inflected; after 8 hrs. 

 the tentacles at the further or distal end were more inflected than 

 those on either side ; after 23 hrs. the meat was well clasped by all 

 the tentacles, excepting by the exterior ones on the two sides. 



(4) Another bit of meat was placed at the opposite or distal 

 end of another leaf, with exactly the same relative results. 



