Toxic Action of Electric Discharge upon B. coli communis. 349 



a source of comparatively low voltage, and transmitted to the nutrient 

 medium through the ordinary form of Kohlrausch platinum electrode which 

 was immersed in it. But this suggestion immediately raises the question 

 as to whether the effect detected by Thornton bore any relation to the 

 direct action of the current, or was connected with the chemical changes 

 produced in the atmosphere surrounding the discharge point. Thornton 

 ■considers that the fatal result of the discharge may be wholly attributed 

 to " the direct influence of, and contact with, ions in the electric wind." 

 It is hardly conceivable, however, that mere ionic bombardment could be 

 responsible for such deep-seated action as was observed, especially in con- 

 sideration of the fact that ions have practically no penetrating power in 

 the presence of water, a film of which must have always intervened between 

 the organism and the discharge. 



Foulerton and Kellas,* as the result of experiments carried out along lines 

 similar to those described by Thornton, employing in many cases the same 

 species of bacteria, had previously arrived at the conclusion that electric 

 .discharge itself was not deleterious to the organisms. They found that 

 i£ emulsions " of bacteria in water became sterile after subjection to the 

 •discharge in air and in various artificial atmospheres, but considered that 

 .the fatal effect was due, not to the current, but to the products of the 

 discharge, viz., nitric and nitrous acids in air and hydrogen peroxide in 

 hydrogen. Qualitative and quantitative tests of distilled water, after sub- 

 jection to the discharge, revealed the fact that these substances were indeed 

 present in measurable quantities, and subsequent trials showed that such 

 ■concentrations of them were fatal to bacteria, independent of the discharge. 

 It is possible that the results obtained by Foulerton and Kellas cannot be 

 directly applied to explain Thornton's experiments, because of the different 

 electrical conditions. In their experiments the bacteria were contained in 

 vwater in a test-tube and the current was discharged from the points of a 

 platinum brush suspended over the surface, earth connection being made 

 through a platinum wire sealed into the bottom of the tube. In all cases 

 the high-tension discharge from the brush of platinum points was oscillatory 

 in character, and it might therefore be expected that any effects produced by 

 the action of the discharge upon the atmosphere would be enhanced, while 

 effects due to direct action of an electric current should be far less apparent. 



The results obtained by Thornton with the apparatus depicted in his fig. 2 

 suggest that the products of discharge, and not the ions, were the active 

 factor. In these experiments the current passed, not through the bacteria- 



* "Action on Bacteria of Electrical Discharges," 'Eoy. Soc. Proc.,' 1906, B, vol. 78, 

 p. 60. 



VOL. LXXXVI. — B. 2 C 



