668 A. Ff. Goldfarb 
one or both nerves, then the legs were amputated usually below the 
knee. We have already considered the objections to this method 
of preventing nerve impulses from reaching the amputated end, and 
it is hardly necessary to repeat them here. ‘The limbs regenerated 
the missing parts as readily as the control animals. ‘The changes 
in the nerves are of no specialimportance since they were essentially 
the same as those already described. 
Second Amputation of Paralyzed Limbs 
Of far greater importance was the series of experiments in which 
after varying intervals following removal of the nerve cord the 
limbs were amputated a second time. A sufficiently long period, 
i.e., from 108 to 157 days intervened between successive amputa- 
tions, for the motor nerves to degenerate completely, and along. 
their whole length. The second amputation was made at the 
same or more proximal or more distal level than the first amputa- 
tion. In every case there was complete paralysis throughout the 
experiment. Nevertheless typical legs were regenerated. 
The result furnishes strong evidence that the stimulus for regener- 
ation is not a nerve stimulus, or more correctly not a motor stimulus. 
In the animals of this series the motor cells as well as the motor 
fibers of the limb had been destroyed, the former directly, the latter 
through subsequent degeneration. The sensory fibers had also 
degenerated for considerable distance, and had not yet begun to 
regenerate, so that the possibility that the mere presence of the nerve 
fiber may have been the stimulating factor cannot hold. \n conclu- 
sion it might be added that the limbs differed in no way from those 
in the control series in which the legs were also amputated a second 
time. 
The legs of the following inidviduals were examined. ‘The time 
between the original operation and the subsequent amputation of 
the leg is given in column 2, between this date and the last removal 
of the leg, in column 4. 
