234 HOWARD J. CURTIS 



was tested by the strength of the reaction it could evoke from a frog's 

 muscle. A heated controversy arose between Galvani and Volta 

 over the question of whether "animal electricity" was different from 

 "mineral electricity," and whether the ability of an animal to generate 

 electricity was one of the fundamental characteristics of life. This 

 controversy stimulated a great deal of interest in the electrical charac- 

 teristics of cells and tissues, which persists to the present day. 



From time to time it has been postulated that electrical forces or 

 electric currents are responsible for the function of almost every organ 

 of the body. These postulates have been not without some founda- 

 tion, for it was soon found that electric currents were generated not 

 only by nerve and muscle, but if careful measurements were made 

 electric currents could be detected around practically every organ in 

 the body. 



The uses of electricity in medical therapy have not been neglected, 

 and at one time or another it is probable that electric currents have 

 been advocated as a remedy for practically every disease that af- 

 flicts mankind. It was not many years ago when a doctor's office 

 was not complete without a static machine for the administration of 

 electric treatments, and as recently as 1900 books were being pub- 

 lished on the best methods of applying electric treatments for the 

 cure of practically every disease. These were sincere efforts by the 

 medical profession to find some use for this new discovery. How- 

 ever, medical quacks found this a most profitable field, and electric 

 belts or similar appliances are probably still for sale in some parts 

 of this country. 



This situation could not have prevailed if there had been no ele- 

 ment of truth in these theories and suppositions. Certain of the 

 electric potentials found to exist in and around cells and tissues are 

 now known to be of primary importance for the function of the cell, 

 others are by-products of cellular function, and a great many others 

 are measurement artifacts. As a result of a number of systematic 

 investigations, these phenomena are now reasonably well under- 

 stood, at least from a measurement point of view. There is no real 

 excuse now for investigators to commit gross errors of measurement 

 or interpretation as has occurred so often in the past in this field. 

 Measuring equipment can be obtained that is accurate and inexpen- 

 sive, and the sources of error are now well understood. 



This chapter will attempt to outline some of the potentialities 

 of this method and to point out some of the commonest sources of 

 error. 



