PREFACE. Vii 



of considerable intensity and short duration is led through a 

 muscle, and the condition of the muscle is immediately after 

 investigated galvanoscopically, it is found that a sudden change 

 as regards its electrical condition takes place, of such a kind 

 that the current led off from the organ, at first feebly 'negative,' 

 that is, in the opposite direction to that of the external current, 

 becomes strongly ' positive,' that is, in the same direction. 



Similarly, Prof. Hermann, in a Paper published in Pfluger's 

 Archiv in January 1883, gave an account of the same pheno- 

 mena, which, as regards muscle, closely accorded with that of 

 Hering, adding new proof of the polar localisation of the electro- 

 motive changes observed ; and he further extended his researches 

 from muscle to nerve so as to include all the subjects investi- 

 gated by du Bois, with the exception of that of the electrical 

 organs of fish. Prof. Hering's paper ('Ueber Veranderungen 

 des electromotorischen Verhalten der Muskeln in Folge electri- 

 scher Reizung') we have not thought it necessary to translate, 

 preferring to present to the reader the more advanced view 

 of the subject contained in his second paper, which appeared at 

 the same time with it, under the title, ' Ueber du Bois-Reymond's 

 Untersuchungen der secundarelectromotorischen Erscheinungen 

 am Muskel.' The reader will find in the three papers satis- 

 factory evidence that all these distinguished observers have 

 had before them the same facts, though from difference of method, 

 or from other causes, they may have been presented to them 

 under different aspects. But in all that belongs to the doctrine 

 of c secondary electromotive phenomena ' it will be equally clear 

 to him, that while Hering and Hermann tend in the same direc- 

 tion, their views are utterly at variance with those of the great 

 founder of Electro-physiology. 



Du Bois holds that just as in the ordinary polarisation of 

 porous bodies soaked with electrolytic liquids, the change affects 

 all parts through which branches of current pass, so in polarisa- 

 tion of nerve and muscle, whether negative or positive, the 

 change affects all the parts traversed in a degree which depends 

 upon the current density, and that as regards positive polarisa- 



