iv ELECTROMOTIVE ACTION IN MUSCLE 339 



gradually induce the same effect that is suddenly brought about 

 when a mechanical or thermic section is applied by any method. 

 Hermann (9) showed later, by conclusive experiments, that 

 the E.M.F. of excised muscles does sink considerably through 

 cooling, and rises again on increasing the temperature ; according 

 to Hermann the variation may rise to 22 / Q within the range" 

 of vital temperature, but is probably still greater, since, in 

 the methods used, the deeper layers may not be affected in the 

 same degree as the more superficial. 



If in preparing, as well as in leading off from the muscle, 

 care is taken to avoid all possible injury (especially at the tendon 

 end), the electromotive effect is either negative, or the P.D. between 

 surface and natural section is so negligible that it might legiti- 

 mately be ascribed to inevitable disturbances from exposure. 

 Moistening the natural section with fluids which do not attack 

 the muscle-substance chemically, e.g. physiological NaCl solution, 

 gives no perceptible development of current. Later on in du 

 Bois-Eeymond's investigations, it appeared that the supposed 

 effect of cooling is not so important in the development of 

 parelectronomy, but that all muscles are, rather, permanently at a 

 more or less pronounced grade of the parelectronornic condition. 

 This state is not therefore abnormal and an effect of cooling, but 

 is perfectly normal and regular. As Hermann remarks, the term 

 " parelectronomic " might with more justice be applied to the state 

 in which current is fully developed between end of tendon and 

 muscle, than to that which du Bois-Reymond designates by it. 



Du Bois-Reymorid's explanation of the parelectronomic state 

 will be discussed below. Here it can only be said that he 

 attributes the failure, or absence, of current between surface 

 and natural section to the presence of a thin layer of specific 

 muscle-substance at the natural section, which by its contrary 

 action partly compensates, or even over-compensates (i.e. abolishes), 

 the normal electromotive action of the remaining mass of the 

 muscle. 



The production of current when the natural cross-section is 

 moistened with concentrated NaCl solution, acids, or alkalies, 

 or is cut or heated, must accordingly be referred to the chemical, 

 thermic, or mechanical disturbance of this thin sheet, called by 

 du Bois-Reymond the parelectronomic layer. This theory of a 

 parelectronomic condition at various stages of development 



