■ T.\BLE 6 



W represents a series of tests upon the 'whole' (see text) stem of five different colonies. 

 A represents corresponding tests on apical half and B a corresponding series of 

 tests upon the basal half of the 'lohole' stem after cutting the latter into equal halves. 

 Note the small P.D. in W and the opposite direction of the potential in the A and B 

 pieces. A' and A^ represent tests upon apical and basal halves, respectively, of the 

 A pieces. B^ and B- represent tests upon apical and basal halves, respectively, 

 of the B pieces. Note the definite difference of potential in the apical pieces A^ 

 and the marked tendency to reversed direction of fall of potential on the basal 

 pieces B^ 



491 



