Physiological "Polarity" and Electrical Polarity. 345 



If we regard only the readings made when regeneration had 

 proceeded more than twenty-one days, in thirty-six cases the end 

 was positive with respect to the surface, and in eleven cases it was 

 negative, a much more definite result than when all cases are con- 

 sidered. 



The conditions in a regenerating tip do not, therefore, agree 

 with those at a freshly cut end, for the current flows in an oppo- 

 site direction. To be sure, the processes occurring during regen- 

 eration are not the same as those occurring during the breaking 

 down of tissues, and the latter may be the predominant ones im- 

 mediately after a cut is made. The subject, however, needs fur- 

 ther investigation before the causes for this reversal can be more 

 than surmised. 



ELECTRICAL POLARITY AND RATE OF REGENERATION. 



If we look for a relation between electrical polarity in the worm 

 and rate of regeneration, as Mathews has suggested, we find it 

 as difficult to demonstrate as the difference between electrical and 

 physiological polarity. If the average deflection of the galvanom- 

 eter was greater at certain levels where regeneration is known 

 to be rapid than at other levels where it is slow, the connection 

 would be established. For instance, the regeneration of a tail at 

 the posterior end of a worm when only a few posterior segments 

 are cut off, is exceedingly rapid, whereas the regeneration of a 

 heteromorphic tail at the middle of a worm is very slow. The 

 average deflection of the galvanometer in the former case for 

 three readings is, however, 3.4, with the cut end positive instead of 

 negative in every case. In the latter case the average deflection 

 for seven readings is 3.6 (with the end negative) , with no extreme 

 readings to brtng it up. The region in the middle of the worm, 

 where a tail is to regenerate from the posterior end of the anterior 

 piece, gives an a^^erage deflection of 4.7 for seven readings from 

 different worms. When five or six segments are cut from the an- 

 terior end of the worm the average deflection for seven cases was 

 4.6 at the anterior end of the long piece. At the posterior end of 

 the short piece, regeneration would be very slow, and at this end 



