342 T, H. Morgan and Abigail C. Dimon. 



(a) Anterior half of worm, both ends cut 



(long piece) 16.6 Anterior positive 



(b) Short piece from anterior part of an- 



terior half of worm, the posterior 

 end cut somewhat later than the 

 anterior end 22.3 



(c) Same. Anterior end freshly cut. . . . 32.5 Posterior positive 



(d) Short piece from middle part of an- 



terior half of worm, posterior end 

 more freshly cut 27.1 



27.0 



27.9 



(e) Same piece, anterior end freshly cut. 36.2 " " 



( f ) Short piece from anterior part of pos- 



terior half of worm 33-0 " 



(g) Short piece from middle of posterior [ 28.5 Anterior end 



half of worm \ 24.0 positive probably 



(h) Anterior half of (g), posterior end 



freshly cut 22.0 Anterior positive 



(i) Posterior half of (g), anterior end 



freshly cut 34-0 Posterior positive 



In this worm, when the two ends were cut at approximately 

 the same time, which happened in (a), (f) and (g), the piece 

 from the anterior half had its anterior end positive, and the two 

 pieces from the posterior half had their posterior ends positive. 

 In the majority of worms tested, when the two ends of a piece 

 were cut at the same time, the anterior end was positive, regard- 

 less of the position of the piece on the worm.^ If, however, the 

 two ends were cut at different times, which in this worm occurred 

 in six pieces, the end which' had been cut most recently generally 

 had a lower potential than the other. Since the testing with the 

 electrodes on a transverse section and an uninjured surface near 

 that section the end was usually found to be at a lower potential 

 than the surface, the fall of potential was supposed to be due to 



^When, however, the pieces were long (one-half the worm or more), in a 

 majority of cases the posterior end was positive with respect to the anterior. 



