MUSCLES, NERVES, AND ELECTRICAL ORGANS. 187 



4. Under Half repeated. 

 Muscle current : 285', 



P | 190 | 190 



The total of the ascending positive polarisation in the upper 

 half of the muscle is 504, that of the descending- 272. For the 

 lower half the corresponding numbers are 976 and 465. The 

 numbers in themselves are, I may incidentally remark, not to be 

 compared with those mentioned in the previous table, as on this 

 occasion the bobbin of the galvanometer was close up. 



One glance at the table shows that the excess of positive polari- 

 sation cannot be supposed to be attributable to oscillations in the 

 strength of the primary current. These oscillations, which arise in 

 part from defects in the apparatus for regulating the time of 

 closure, are sometimes not apparent, sometimes they have the 

 opposite direction to that which would arouse suspicion, and even 

 when it is otherwise they are much too small to give any grounds 

 for suspicion. Moreover, such an explanation is opposed by the 

 cases of which the table offers three, in which, though the direction 

 of the polarising-current is less favourable to positive polarisation, 

 a preliminary negative deflection appears, and further the not 

 infrequent cases in which the polarisation is purely negative ; for 

 provided the time of closure is equal, either action in two opposite 

 directions, or negative polarisation, imply the existence of a stronger 

 polarising-current. These cases exclude the idea that we have to 

 do with a phenomenon of resistance. 



Another conjecture which offers itself here deserves, however, 

 serious consideration. The whole phenomenon might rest on a 

 deception. As we would expect from the law of the muscle- 

 current, and as is evident from the table, as regards the foregoing 

 case a descending muscle -current prevails in the upper, an as- 

 cending one in the lower half of the muscle. The negative 

 variation and its after-effect are manifest in the upper half as 

 ascending, and in the lower half as descending electromotive action. 

 Consequently the after-effect in the upper half of the muscle, with 

 an ascending polarising-current, will reinforce the positive polarisa- 

 tion, and with a descending one will diminish it. In the under 

 half mutatis mutandis the same will happen. Now since the 

 muscle contracts at the passage of the polarising-current, every- 

 thing might thus be explained on old well-known grounds without 

 having recourse to anything new. 



