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1052 The American Naturalist. [December, 
destroying it by means of the hot platinum wire. These operations 
give the following results. First, as is well known, the headless 
trunk shows no volition nor intelligence. If left without external 
stimulation it will remain quiet, until it dies, just as will the brainless 
frog. Yet, under stimulation, movements are made which are well 
coordinated, though not as perfectly so as when the ganglion is present. 
The trunk will start forward when touched, and will often advance 
its own length or more before becoming quiet again. But the motion 
becomes slower and slower until it ceases or until an obstacle is met, 
and the body is quiet until again stimulated. Some other protective 
motions may also be shown. The trunk will back away from a sudden 
stimulation in front, or the portion of the body touched may be sud- 
denly jerked away, as in the normal animal. Further, if turned 
upon its back it quickly rights itself. All these actions, how- 
ever, are weaker than when the supercesophageal ganglion is present, 
and are not performed with so much precision. The coordination of 
the motion of the legs is less exact, consequently the advance of the 
trunk is much slower, and sometimes when it is overturned several 
attempts are made before it succeeds in righting itself. 
Another fact which is noticeable in regard to the supercesophageal 
ganglion, when a part of the ganglion is destroyed by the hot wire, is 
that the amount of influence exerted by the ganglion appears to 
depend on the amount of it which is left intact. A slight burn 
destroying only a small portion will leave the animal only a very little 
less active than the normal, while if the larger portion of the ganglion 
be burned out it is hard to distinguish the subject as regards its actions 
from the headless trunk. Between these two extremes there are all 
degrees of difference, so that it appears impossible to set any definite 
limit between the reflexes of the headless subject and the animal with 
the greater part of the supercesophageal ganglion destroyed. Moreover, 
the probable occasional presence of internal stimulation from the 
wound complicates the matter still further. Where a portion of the - 
ganglion remains the motions continue a somewhat longer time than 
in the decapitated subject, and often before perfect quiet ensues, 
isolated motions of different legs occur at longer and longer in 
In fact, in the two cases there seems to be an analogy to a delicate — 
machine. In the first case, the decapitated trunk, the machine is set 
in motion by the stimulation but after a time comes to rest. In the 
second case the adjustment is more perfect and a longer time ensues 
before motion ceases. The delicacy of adjustment increases with the 
