Chap.X.] conducting TISSUES. 203 



The appearance presented by the leaves (2) and (3) was 

 very curious, and might be aptly compared with that of a 

 man with his backbone broken and lower extremities par- 

 alysed. Excepting that the line between the two halves 

 was here transverse instead of longitudinal, these leaves were 

 in the same state as some of those in the former experiments, 

 with bits of meat placed on one side of the disc. The case of 

 leaf (4) proves that the spiral vessels of the central trunk 

 may be divided, and yet the motor impulse be transmitted 

 from the distal to the basal end; and this led me at first to 

 suppose that the motor force was sent through the closely 

 surrounding fibrous tissue; and that if one half of this 

 tissue was left undivided, it sufiiced for complete trans- 

 mission. But opposed to this conclusion is the fact that no 

 vessels pass directly from one side of the leaf to the other, 

 and yet, as we have seen, if a rather large bit of meat is 

 placed on one side, the motor impulse is sent, though slowly 

 and impjerfectly, in a transverse direction across the whole 

 breadth of the leaf. Nor can this latter fact be accounted 

 for by supposing that the transmission is affected through 

 the two inosculations, or through the circumferential zigzag 

 line of union, for had this been the case, the exterior ten- 

 tacles on the opposite side of the disc would have been af- 

 fected before the more central ones, which never occurred. 

 We have also seen that the extreme marginal tentacles ap- 

 pear to have no power to transmit an impulse to the adjoin- 

 ing tentacles ; yet the little bundle of vessels which .enters 

 each marginal tentacle sends off a minute branch to those 

 on both sides, and this I have not observed in any other ten- 

 tacles; so that the marginal ones are more closely connected 

 together by spiral vessels than are the others, and yet have 

 much less power of communicating a motor impulse to one 

 another. 



But besides these several facts and arguments we have 

 conclusive evidence that the motor impulse is not sent, at 

 least exclusively, through the spiral vessels, or through the 

 tissue immediately surrounding them. We know that if a 

 bit of meat is placed on a gland (the immediately adjoining 

 ones having been removed) on any part of the disc, all the 

 short surrounding tentacles bend almost simultaneously with 

 great precision towards it. Now there are tentacles on the 



