458 | Oren E. Frazee 
tops of the dishes. This minimized the amount of dust entering 
and still permitted a free circulation of the air. 
Spirogyra was used as food for the tadpoles, and tubifex 
worms for the salamander larva. Stale food was not permitted. 
An excess of food rather than an undersupply was the rule. 
No record has been kept of the temperature. It is known, 
however, to have been fairly constant. There have been no 
great fluctuations in the temperature during the time of an experi- 
ment. | 
An effort was made to handle the animals of the stimulated 
group in the same manner as the animals of the non-stimulated 
group, save for the stimulation which was given the former. 
In the measurement of the entire body, tenths of millimeters 
were secured. In the measurement of the regenerated part, an 
ocular micrometer was used and it was possible to secure the 
measurements in hundredths of millimeters. 
The cut was made in all cases as nearly as possible at the same 
level, at right angles to the notochord, and at the same time. 
A sharp razor was used for the cutting operation. ‘The operation 
proceeded alternately with the stimulated and the non-stimu- 
lated ones. 
The general methods of using the current were as follows: 
(1) The current was taken from an electric lighting wire (alter- 
nating current), passed in series with an incandescent lamp, and 
connected up in series with a resistance coil. ‘The tadpoles were 
placed in tap water in a wooden trough insulated on the inside 
with parafine. They were screened from the electrodes as 
shown in Fig. 1. (2) The current was shunted from a resistance 
coil as shown in Fig. 2. 
DATA 
Experiment r. In this experiment 12 tadpoles of Rana 
pipiens were taken. ‘They were of the same size; were operated 
upon October 9, 1908, when 10 mm. of the tail were removed. 
Three days later, the current from six dry battery cells was sent 
through each one of the tadpoles, the animal being in direct 
