SOME RECENT WORK UPON MUSCLE AND NERVE. 441 



whose work lies in biological or other fields of natural 

 science must realise that since our knowledge of excitable 

 tissues is largely founded upon the study of muscle, a con- 

 troversy which involves the credit or discredit of the chief 

 method employed for its elucidation, is by no means the 

 least interesting" episode in recent physiological science. 



As regards nerve physiology the work of chief interest 

 to the present writer is that which involves the study of the 

 electromotive effects which accompany the presence in this 

 tissue of the state of excitation. There are no known 

 mechanical, chemical or thermal indications to show that 

 nervous tissue has been thrown into the state of activity. 

 Such a state is inferred in motor nerves from the circum- 

 stance that the supplied muscle to which the nerve is distri- 

 buted responds when this nerve is excited. The combined 

 nerve muscle preparation may be likened to an underground 

 fuse leading to a mine where the successful firing of the fuse 

 is indicated by the explosion of the mine. But since the 

 discovery by du Bois Reymond fifty years ago that the 

 state of excitation in nerve was accompanied by a change 

 in electrical state, it has been recognised that the study of 

 this state is a means, and at present the only direct means, 

 for ascertaining the vital characteristics of the nerve itself. 

 A very large number of different methods have been em- 

 ployed for the purpose, but the majority have all involved 

 the frequent excitation of the nerve by a series of stimuli. 

 This necessity has been due to the circumstance that the 

 electrical change which accompanies the molecular dis- 

 turbance is, when evoked by a single stimulus, too feeble 

 and too short-lived to affecf the most sensitive o-alvan- 

 ometer. A vast amount of information has however been 

 obtained from the summed effects of repeated stimulation, 

 the galvanometric indications being under these circum- 

 stances both definite and considerable. By means of an 

 ingenious automatic key, the revolving rheotome, Bernstein, 

 Hermann, Boruttau and others have obtained a history of 

 the development and subsidence of the aggregate or total 

 of this multiple effect, and from such data they have in- 

 ferred the history of each single change. All this is set 



