234 DROSERA ROTUNDIFOLIA. Ona. X. 
glands, and only a few of the immediately surround- 
ing short tentacles are inflected; place it on several 
glands, and many more are acted on; place it on 
thirty or forty, and all the tentacles, including the 
extreme marginal ones, become closely inflected. We 
thus see that the impulses proceeding from a number 
of glands strengthen one another, spread farther, and 
act on a larger number of tentacles, than the im- 
pulse from any single gland. 
Transmission of the Motor Impulse—In every case 
the impulse from a gland has to travel for at least 
a short distance to the basal part of the tentacle, 
the upper part and the gland itself being merely 
carried by the inflection of the lower part. The 
impulse is thus always transmitted down nearly 
the whole length of the pedicel. When the central 
glands are stimulated, and the extreme marginal ten- 
tacles become inflected, the impulse is transmitted 
across half the diameter of the disc; and when the 
glands on one side of the disc are stimulated, the 
impulse is transmitted across nearly the whole width 
of the disc. A gland transmits its motor impulse 
far more easily and quickly down its own tentacle 
to the bending place than across the disc to neigh- 
bouring tentacles. Thus a minute dose of a very 
weak solution of ammonia, if given to one of the 
glands of the exterior tentacles, causes it to bend and 
reach the centre; whereas a large drop of the same 
solution, given to a score of glands on the dise, will 
not cause through their combined influence the least 
inflection of the exterior tentacles. Again, when a 
bit of meat is placed on the gland of an exterior 
tentacle, I have seen movement in ten seconds, and 
repeatedly within a minute; but a much larger bit 
placed on several glands on the disc does not cause 
