SHORT ELECTRIC WAVE RADIATION 547 



appears to be another and secondary factor which can only be demon- 

 strated when the first is ruled out. This secondary factor is spoken of 

 by those who are attempting to demonstrate it as "an effect other than 

 that of simple heat." 



Schereschewsky in his early work believed that the heat factor was 

 only partly responsible for the effects observed, and he was also impressed 

 with the possibility of a differential action on the part of various fre- 

 quencies. He had observed that tumorous tissue seemed to be more 

 susceptible to this radiation than other tissues, and to test this he chose 

 the tissue cells of transplantable tumors. He selected for his experiments 

 a most virulent mouse sarcoma, implantation of which yielded 95 to 96 

 per cent of "takes." Treatment was localized as far as was possible to 

 the cancer cells, the tumors being placed between small insulated plates. 

 Soon after beginning his experiments Schereschewsky noted that in 

 favorable cases treatment had a pronounced effect upon the tumor, the 

 mass seeming to become much smaller and softer almost immediately 

 after exposure. Many technical difficulties arose during the course of 

 these experiments, but the most troublesome w^as the association of this 

 tumor with a diphtheroid bacillus, which of itself is pathogenic for mice. 

 However, despite all difficulties, of 403 mice treated 100 recovered tumor- 

 free. No case of spontaneous recession of the tumor was observed in 

 230 control mice. 



In these experiments Schereschewsky did not attempt to rule out the 

 heat factor completely. Schliephake (33, 34) had observed differential 

 heating effects on various tissues of the animal body and came to the 

 conclusion that there was some indication that the biological effects of 

 ultra-high-frequency fields may be due in part to some action other than 

 that of simple heat, but he, like Schereschewsky, had not ehminated the 

 heat factor. 



McKinley (13), in work with the nervous tissue of the frog, attempted 

 to rule out the heat factor by comparing the action of both external heat 

 and the high-frequency field on this tissue. He found that in irradiations 

 of the isolated spinal cord, exposed by dissection, definite action on the 

 central nervous system was demonstrated. External heat over a wide 

 range of temperatures did not duplicate the characteristic action of the 

 high-frequency field on this tissue. Headlee and Burdette (7) found 

 indications of differences in lethal time from high-frequency radiation in 

 insects, the differences in time apparently corresponding to the amount 

 of nervous tissue present. 



These somewhat indefinite indications of an effect other than simple 

 heat were given additional and very strong support by Szymanowski and 

 Hicks (36) who were able to attenuate diphtheria toxin by means of the 

 high-frequency field. In a series of very carefully conducted experiments 

 these two workers completely ruled out all gross heating effects and yet 



