CONTROL OF ORGANIC POLARITY 



473 



electric current (fig. 1, d, e). These observations suggested to 

 me the possibility that reversal of polarity in a part of a re- 

 generating piece of cell or whole animal might be associated with 



Fig. 1 a, h, and c are heteromorphic individuals of Bursaria showing different 

 degrees of structural dedifferentiation. The chief criterion for the heteropolar 

 condition in c is the beat of the cilia in opposite directions, d and e show the 

 direction of ciliary beat in Paramecium in a direct electric current of proper 

 density, c and e correspond to one another in direction of their ciliary beat. 

 d and e might be compared respectively, to heteromorphic 'tails' and 'heads.' 



a reversal of electrical differences of potential, such as those dis- 

 covered in Tubularia, Pennaria, and Campanularia by Mathews.^ 



^Mathews, A. P., Electrical polarity in the hydroids. Am. Jour. Physiol., 

 1903, vol. 8, p. 294. 



