550 BIOLOGICAL EFFECTS OF RADIATION 



Dissociation and size changes in bacteria are, apparently, produced by 

 this agency, and such action by electric fields may be of value to the 

 modern bacteriologist. 



The possibility that this agent produces a specific effect on nervous 

 tissue, and to a lesser degree on other tissues, opens the door to important 

 researches in both physiology and therapeutics. 



The destruction of various parts of the nervous system, especially the 

 brain, without dissection of the tissue surrounding them is shown to be 

 possible and this may be of some use in the study of the function of these 

 parts. 



Modification of the course of development in vertebrate embryos is a 

 possibility and in the future the proper manipulation of this source of 

 energy may prove of value to the experimental embryologist. 



It is at least strongly indicated in this paper that high-frequency fields 

 and external heat are in no way comparable. Many of the observed 

 effects of electric fields could not be duplicated with external heat as the 

 agency, and, according to modern physical theory, such duplication is 

 not to be expected. The action of the electric field is carried to the very 

 foundations of the matter exposed to its influence. This action is 

 instantly distributed throughout the whole body of the specimen and 

 does not depend, as does external heat, upon a relatively slow penetration. 

 The specific action of high-frequency fields is not clearly understood, but 

 in such substances as the animal and plant body, exposed as indicated 

 in this paper, it is suggested that the following actions may occur : 



Conduction currents, or the flow of ions, are set up in the tissues of the 

 body and these currents oscillate at the frequency of the field. It is 

 possible that the specific effects on nervous tissue are due to conduction 

 currents. 



All permanent molecular dipoles are rotated by the action of the field. 

 In living material, with its very large protein molecules, this may be 

 an important factor in bringing about changes in protoplasmic balance. 



Under the action of high frequencies temporary dipoles would tend to 

 form and this would introduce possible hysteresis effects, a phenomenon 

 which accounts in part for the generation of internal heat. 



Any body potentials which might be present between or within 

 tissues might be altered by the rapidly changing potential of the field. 



APPARATUS 

 GENERAL DESCRIPTION 



The recent increase in commercial importance of the ultra-high- 

 frequency radio spectrum has greatly advanced the apparatus and circuits 

 available for the production of high-frequency oscillating currents in the 

 region of 60 megacycles. 



