Effect of Electrical Stimulation 473 
DISCUSSION 
That growth in plants is accelerated by the electrical current 
within certain limits, has been shown by a number of investigators. 
In the case of animals, Lombardini (’68) and Windle (’93, ’95) 
found that a current passing transversely through the chick 
embryo caused it to develop abnormally, or to cease developing 
altogether. Rusconi (’40) believed that a slight current acceler- 
ated the development of the frog’s egg. It is to be noted that 
very little work has been done to show the effect upon the growth 
of animal tissue, and so far as the author knows the present work 
is the first attempt to determine the effect of electricity upon 
regeneration. 
The experiments here recorded indicate that an electrical 
stimulation of animal tissue may be beneficial for purposes of 
regeneration under two conditions: First, when the current den- 
sity is small and the voltage comparatively low. Second, when 
the current density is small and the voltage comparatively high, 
provided that the stimulation be of short duration; furthermore, 
they show that any considerable degree of current density, or a 
high voltage applied for more than a very short time, decreases 
the rate of regeneration. 
The data in Experiments 2 and 3,° both of which were pre- 
liminary in their nature, show that a strong current is harmful. 
It shows in Experiments 4 and 5 with a current density of 1660 
6 in each instance, and with a voltage of 110 that repeated 
daily stimulations with such a current are harmful whether the 
number of repetitions is two or six. In Experiment 6 with 
young individuals seven days old, repeated stimulations, at short 
intervals of time, with a current density of 116.6 6, and voltage 
110, is harmful, even if the total stimulation amounts to no more 
than fifteen minutes. In Experiment 7, with much older individ- 
uals, thirty days old, the data show that with a current density of 
10 6 and voltage 110, a six-minute stimulation gives beneficial 
results. In Experiment 8 it is seen that with tadpoles of the same 
5In Experiment 1 the number of individuals taken for comparison is too small to make the result 
of much value. 
