140 



PHYSIOLOGY OF MUSCLES AND NERVES. 



be possible that these two conditions differ in the re- 

 lation which they bear to the excitement. Indeed, 

 Pfliiger supposed that excitement occm's only at the 

 commencement of katelectrotonus and at the cessation 

 of anelectrotonus. On the basis of this hypothesis the 

 phenomena of the law of pulsations may be explained ; 

 and it becomes intelligible why on the closing and 

 opening of the current pulsations sometimes occur and 

 are sometimes absent. In order, however, fully to 



Fig. 33. Electuotonus. 



understand this hypothesis and the law of pulsations 

 based upon it, we must study the phenomena of elec- 

 trotonus more closely than we have yet done. 



5. AVe have already seen that the excitability is in- 

 creased on the side of the kathode during the closing 

 of the current, and is decreased on the side of the 

 anode. Easy as it is to prove this law under the appli- 

 cation of weak, or medium currents, it is sometimes 

 very hard to do so when the current causing the elec- 

 trotonus is strong. Let us again imagine that the 



