498 ANNALS NEW YORK ACADEMY OF SCIENCES 



The charge passing through the organs, and hence, also, the energy, 

 depend on the resistance of the external circuit, as well as on the elec- 

 trical characteristics of the tissue. For comparison with the chemical 

 measurements, it is, of course, essential that the external resistance 

 should be the same in the electrical, as in the chemical, experiments. 

 Otherwise, the choice of an external resistance is, within limits, un- 

 important. The fish on which the electrical measurements have been 

 made form three groups according to size, with average lengths of 

 67, 103, and 180 cm. We have used an external resistance of 200 ohms 

 with the two groups of smaller length, and of 100 ohms with the other 

 group. These resistances were roughly the same as the internal re- 

 sistances, averaged over the time of the impulse, of the part of the or- 

 gans between the electrodes. Consequently, the condition of the ex- 

 periment approximated the requirement for maximum energy in the 

 external circuit. 



The results are summarized in table 1, which shows, for each speci- 

 men and for the average of each group, the electromotive force per cm., 

 the charge passing in one impulse through 1 cm.^ of electroplax layer, 

 and the total electric energy produced in one impulse in 1 cm.^ of elec- 

 tric tissue. With the electrical units employed, the product of the elec- 

 tromotive force per cm. by the charge per cm.^ would give the energy 

 per cm.^ in microjoules. For more convenient comparison with the 

 chemical energies reported by Nachmansohn, the energies have been 

 given, instead, in microcalories. Since the tissue has nearly unit spe- 

 cific gravity, the energy per cm.^ may be taken as the energy per gm., 

 without serious error. 



It has already been mentioned that the assumption made in the cal- 

 culations, that the right and left organs discharge simultaneously, 

 though probable, is still unproved. If the fact should be that the or- 

 gans discharge separately, then the given values of the charge per cm.^ 

 and the energy per cm.^ would have to be doubled. The same correc- 

 tion would have to be applied to the values of the chemical energy, and, 

 therefore, the comparison of the electrical and chemical energies made 

 by Nachmansohn is valid in either case. 



The individual values of electromotive force per cm. show a mean 

 deviation of 12 per cent from the average of the group. The mean 

 deviation of the charge per cm.^ is 15 per cent, and that of the energy 

 per cm.^ is 23 per cent. The risk of a serious uncertainty in the aver- 

 ages, beyond that indicated by these deviations, depends on the possi- 

 bility that the equations used in the computation are seriously in error. 

 The evidence by which they were justified has already been given. 



