318 L. II. HYMAN AND A. W. BELLAMY. 



however, is not really a theory of the cause of the bioelectric 

 currents, but merely a statement of the general laws of these cur- 

 rents. 2 The principal terms of the alteration theory are : that the 

 uninjured resting muscle or nerve is isoelectric ; that all potential 

 differences arising in muscle or nerve are due to physiological 

 alterations of their substance ; that any injured place or any stimu- 

 lated place becomes electronegative (galv.) to intact or resting 

 regions ; and that the electronegativity is the consequence of the 

 injury or stimulation (cf. Hermann, '79, p. 235). These state- 

 ments are now, of course, accepted facts of electrophysiology. An 

 explanation of the source of the potential differences due to injury 

 and stimulation was not included in the alteration theory, and 

 Hermann (I.e., p. 240) was at this later period disinclined to 

 consider the possibility of a chemical origin of the bioelectric 

 currents. 



A viewpoint very similar to the early conceptions of Hermann 

 quoted above was, however, soon developed by Hering. This 

 viewpoint is suggested in a publication by Hering in 18/9, in which 

 (p. 242) he proposes the possibility that "an der Stellen wo der 

 Strom die contractile Substanz der Einselfaser betritt oder ver- 

 lasst, eine chemische Alteration dieser Substanz stattfinden kann, 

 welche in iibrigen durchflossenen Strecke nicht statthat." Hering 

 presented his conception of the metabolic origin of the bioelectric 

 currents in 1888. In this paper Hering expresses the belief that 

 all of the functions of living matter are metabolic i.e., chemical 

 in nature, either, in general, assimilatory or dissimilatory, and that 

 alterations of chemical function are responsible for the bioelectric 

 currents. Some typical quotations may be given (pp. 250-251) : 

 "... nearly twenty years ago . . . the prevailing conception of 

 the facts of general nerve physiology was strictly physical. I had, 



2 The alteration theory may be considered as a theory as concerns the 

 current of injury which it regards as due to alterations at the cut surface 

 rather than to the exposure of a previously existing negativity at the cut sur- 

 face. This latter point of view is presented by Bernstein ('12) and the question 

 may be regarded as still open. However, alterations undoubtedly occur at 

 the cut surface, due to the cutting, and it is rather more than likely that 

 such alterations play a role in the current of injury, even though Hermann's 

 crucial experiment, supposed to show that a measurable interval elapses 

 between the cutting and the full development of the electronegativity, be 

 discarded because of inadequate technic. 



