X PREFACE. 



from the moment that it was shown by Hermann and Hering's 

 researches, that the well-known electromotive after-effects of the 

 current in nerve (du Bois' electrotonus) have their counterparts 

 in muscle, that is, that the electrical state of a muscle which 

 is traversed axially by a current is subject to polar variations 

 which correspond to an- and cathelectrotonus, it at once became 

 of interest to enquire how these variations are linked to con- 

 comitant changes in what must always be regarded as the 

 essential function of muscle that of contracting in response 

 to stimulation. 



In 1 88 1 it was discovered by Engelmann that the anodic and 

 cathodic localisation of the closing and opening excitatory eife'cts 

 could be demonstrated in the heart of the frog, and Hering 

 showed how, with the aid of the double myograph, as much 

 could be done with a striated muscle. Electrotonus of muscle 

 was thus in a certain sense demonstrated, but to complete 

 the proof it was necessary to show that as cathelectrotonus 

 is represented by contraction, so anelectrotonus is represented 

 by relaxation. This was accomplished by Prof. Biedermann, 

 Hering's coadjutor at Prague, in I883 1 . It was necessary 

 for the purpose to employ as subject of experiment a muscular 

 structure capable of persistent tonus, for it was only in such 

 a structure that relaxation could be observed. The required 

 condition was found to be fulfilled by the heart of the snail 

 (Helix pomatia), which, as Biedermann discovered, can generally 

 be thrown into spasm of sufficient duration for the purpose. 

 by the simple expedient of allowing the ventricle to contract 

 against unwonted resistance. By the observation that the 

 closure of a battery-current through the heart leads to relaxa- 

 tion which takes its start from the anode, just as in the relaxed 

 heart, the closing contraction takes its start from the cathode, 

 Biedermann was able to prove that in that structure, relaxation 

 of muscle already contracted is as characteristic of anelectro-, 

 tonus, as contraction of relaxed muscle is of cathelectrotonus. 



1 W. Biedermann, Ueber das Here von Helix pomatia. (Ein Beitrag zur ver- 

 gleichenden Physiologie der Muskeln.) Wiener Sitzungsberichte, vol. Ixxxix. 19-55. 



