ELECTRICAL POLARITY IN OBELIA 



483 



the older basal end. Now, after isolation of the piece of the 

 stem, the regeneration process sets in at the basal as well as the 

 apical end and also at the cut ends of the branches. Usually 



TABLE 1 



Electrical difference of potential between ends of apical three-fourths of the main 

 ste?ns of Obelia colonies; the latter are designated by the numbers at the top of the 

 table. Numbers represent differences between successive galvanometer deflections 

 on the scale. A gives the tests on the main stem made immediatehj after removing 

 branches. B, tests made twenty-four hours after removing branches, i.e., at the end 

 of twenty-four hours' regeneration. The — sign indicates that the apical end is 

 electronegative to the basal end. The + sign may or may not indicate the opposite 

 condition. See text for explanation 



polyps appear at all these places. This means of course that 

 after twenty-four hours of regeneration of the basal end the 

 tissue has taken on the role and properties of a growing tissue 

 similar to that at the apical end, and consequently its electrical 



