polarizing electrodes of low resistance^ in nearly perfect 



electrodes R )■ Ri-f R2 — ^'O" In the present trials^ minimum 



resistance was obtained with galvanized iron electrodes the 

 area of v*iich nearly equalled that of the cross section of 

 the tanko Other types of electrodes were not triedo It maj 

 be noted that in the above table j, ^2/^1 pi"ogi"es3ively departs 

 from an initial Oo25/l ratio| the reason is not clear-o 



A series of experiments were planned with a source poten- 

 tial of 95 voltsj currents of 2 3 3^ and I4 amps^ and on-frac<= 

 tion Oo25s ^'t 15 ropoSoj to demonstrate that the reaction of 

 the fish was the same as at the higher source voltage (220) 

 used by Morgan, Unfortunately only two fish were available 

 at the time the apparatus was adjusted for this experimento 

 These were used in replicate trials (reversing the polarity 

 of the electrodes) at 2 ampso but they died before further 

 experiments could be performed due to failure of the aquarium 

 water supplyo Of the four trials total positive response 

 was evoked in three and partial positive response on oneo 

 Although the data are meager and therefore non-conclusive j 

 they are comparable with those of Morgan at the same currentj 

 on-fraction, and frequency but at 220 volts source j and indi- 

 cate the general validity of the reasoning in the preceding 

 paragraphs o 



REDUCTION OF ON-FRACnON OF A CYCLE 



IVro sets of experiments were tried with a very limited 

 available supply of large aholehole ^ similar in size (9 to 

 13 centimeters) to those used by Morgan, In one/ Morgan's 

 revolving disk interrupter was used) in the other j, a specially- 

 designed plunging electrode interrupter was used. The gal- 

 vanized iron electrodes in the 12 x 2 x 1-foot tank almost 

 covered the cross-section of the water column and had a 

 water-exposed area of about 1700 square centimeters o The 

 fish were confined by two gates at the center of the tank. 

 When the current was turned on, both gates were removed 

 simultaneously so that the fish was free to move to either 

 the positive or the negative electrodeo 



The results are included in table 11 For conparison 

 some of Morgan's results are included in table 12 o As 

 total response- — rapid and decisive movement to the positive 

 pole from which there is no withdrawal— was desired as the 

 criterion of attraction^ both Morgan's and the writer's 

 results are recorded as the number of positive trials an^. 

 number of non-positive trials j, rather than as time spent in 

 the positive half of the tank out of a total test period of 

 one minute. 



7U 



