250 DROSERA ROTUNDIFOLIA. Cua. X. 
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 sufficed for 
complete transmission. 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 imperfectly, 
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 effected through 
the two inosculations, or through the circumferential 
zigzag line of union, for had this been the case, the 
exterior tentacles on the opposite side of the disc 
would have been affected before the more central ones, 
which never occurred. We have also seen that the 
extreme marginal tentacles appear to have no power 
to transmit an impulse to the adjoining 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 communi- 
cating 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) ou any part of the disc, all the short sur- 
