Chap. X. TEANSMISSION OF MOTOR IMPULSE. 241 



bending of tlie tentacle; and it appears to be dis- 

 charged at first with much greater force than after- 

 wards. Thus, in the case above given of a small fly- 

 naturally caught by a few glands on one side of a leaf, 

 an impulse was slowly transmitted from them across 

 the whole breadth of the leaf, causing the opposite 

 tentacles to be temporarily inflected, but the glands 

 which remained in contact with the insect, though 

 they continued for several days to send an impulse 

 down their own pedicels to the bending place, did 

 not prevent the tentacles on the opposite side from 

 quickly re-expanding ; so that the motor discharge 

 must at first have been more powerful than afterwards. 

 When an object of any kind is placed on the disc, 

 and the surrounding tentacles are inflected, their 

 glands secrete more copiously and the secretion 

 becomes acid, so that some influence is sent to 

 them from the discal glands. This change in the 

 nature and amount of the secretion cannot depend 

 on the bending of the tentacles, as the glands of the 

 short central tentacles secrete acid when an object is 

 placed on them, though they do not themselves bend. 

 Therefore I inferred that the glands of the disc sent 

 some influence up the surrounding tentacles to their 

 glands, and that these reflected back a motor impulse 

 to their basal parts ; but this view was soon proved 

 erroneous. It was found by many trials that tentacles 

 with their glands closely cut off by sharp scissors 

 often become inflected and again re-expand, still 

 appearing healthy. One which was observed con- 

 tinued healthy for ten days after the operation. I 

 therefore cut the glands off twenty-five tentacles, 

 at different times and on different leaves, and seven- 

 teen of these soon became inflected, and afterwards 

 re-expanded. The re-expansion commenced in about 



