74 CONTRIBUTION TO THE THEORY OF THE BREAK-CONTRACTION. 



Griitzner's conclusions. Here we have only to enquire how far 

 Biedermann's researches on the break-tetanus, with its associated 

 phenomena, favour the theory that the break-contraction is deter- 

 mined by polarisation. 



One of Biedermann's most remarkable results is the retardation 

 of the break-contraction, which he obtained on treating- the nerve 

 with an alcoholic solution of common salt and with salts of potas- 

 sium, and which he regarded as standing in the closest relationship 

 to the break-tetanus. The reasons which he has adduced for this 

 opinion appear absolutely conclusive, and furnish a new argument 

 for Engelmann's well-known explanation. There is no direct con- 

 nection between this retarded break-contraction and the ordinary 

 one, as Biedermann himself states. The chief point is that, in this 

 case also, the excitation proceeds from the positive pole (the nega- 

 tive pole of the polarisation-current), and that the susceptibility of 

 the nerve to polarisation increases after treatment with alcohol. 



Hitherto I have dealt exclusively with the contraction appearing 

 when the current is completely opened. There is, however, another 

 phenomenon described as a break-contraction, which shows itself 

 when the polarising current is very suddenly weakened without 

 being annulled. This contraction I have not studied at all, and 

 the investigations made on the subject up to this time are too scanty 

 to permit of a theory being formed with regard to it. We do not 

 know with any certainty whence the excitation-effect comes, whether 

 from the positive or from the negative pole. As Griitzner in his 

 paper (p. 143) states that he is -engaged on the subject, I have not 

 thought it well to commence any investigations upon it. 



If, therefore, we leave out of account the case of the break-con- 

 traction evoked by a sudden weakening of the current, all the well- 

 established facts, as I have endeavoured to show, point to the con- 

 clusion that the, break-contraction and all the phenomena occurring on 

 breaking a polarising current are attributable to the polarisation-current, 

 with which, in certain exceptional instances, the nerve-current co- 

 operates. 



