474 Oren E. Frazee 
age as in number seven, harmful results appear when the individuals 
are stimulated with a current density of 8.3 6 and voltage 110 for 
a period of one hour. In this set, however, the later behavior 
points toward positive effects. In number nine in which the 
individuals are slightly younger (and in which stimulation lasted 
for an hour), beneficial results occur with a current density of 
5 6 and a voltage of 40. It is interesting to note, in connection 
with the effect of electrical stimulation upon the rate of regenera- 
tion, that slight stimulation seems to increase the animal’s activ- 
ity, while any considerable degree of stimulation decreases its 
activity. 
SUMMARY 
1 With a current density of 5 6 and a voltage of 40, stimula- 
tion of 18 of 36 individuals of Rana pipiens, 14 to 18.1 mm. in 
length, for an hour gave for the 18 stimulated ones, from 9g to 
26 per cent more in the amount of tissue regenerated than for the 
remaining 18 non-stimulated. . 
2 With a current density of 8.3 d and voltage of 110, stimulation 
of 17 of 34 individuals of Amblystoma jeffersonianum, 23.5 to 
31 mm. in length, gave for the 17 stimulated ones from I to 8 + 
per cent less in the amount of tissue regenerated than for the 
remaining 17 non-stimulated. 
3 With a current density of 10 6 and voltage of 110, stimula- 
tion of 40 of 80 individuals of Amblystoma jeffersonianum, from 
20 to 28.5 mm. in length, gave for the 40 stimulated ones from 
2.6 to 5 per cent more in the amount of tissue regenerated than 
for the remaining 40 non-stimulated. 
4 With a current density of 116.6 9 and voltage 110, repeated 
stimulations at intervals of one-half minute to two minutes of 10 of 
20 larve of Amblystoma jeffersonianum, from 12 to 14 mm, in 
length, gave for the 10 stimulated ones about 10 per cent less in 
the amount regenerated than the remaining 10 non-stimulated. 
5 With a current density of 1660 6 and voltage of 110, repeated 
daily stimulations, of two or more times, of 10 of 20 individuals of 
Rana pipiens, from 39-52 mm. in length, gave for the ro stimu- 
