490 E. J. LUND 



This peculiar opposed direction of fall of potential in the apical 

 and basal pieces of the same stem suggested a further test by 

 the procedure in the following experiment. Five actively grow- 

 ing colonies, the main stems of which are numbered 1 to 5 in 

 table 6, were used. The total length of the stems were, respec- 

 tively, 100, 85, 75, 115, and 95 mm. The piece from each stem 

 included between the cuts x and z in figure 2 was tested first. 

 The lengths of the pieces from stems 1 to 5 were, respectively, 

 64, 57, 57, 83 and 70 mm The results are given in table 6 W, 

 It will be noticed that while the apical ends in four of the stems 

 are electronegative to the basal ends, still the differences are 

 small. In the piece from stem no. 1 no P.D. could be detected. 

 Each one of the five pieces was now cut at y, figTire 2, into two 

 pieces of exactly equal length and then tested immediately. 

 The results from the apical pieces are given in table 6 A, while 

 the corresponding tests on the B pieces are given in the same table 

 in B. It will be observed that the P.D. in every one of the A 

 pieces is quite large, the apical end again being electronegative 

 to the basal end. All the B pieces show a marked P.D. in the 

 opposite direction; this difference is, however, not as large in 

 the B pieces as in the corresponding A pieces. 



Each one of the A and B pieces was now cut into two equal 

 parts at m and n, figure 2, and tested at once. The pieces from 

 the same stem are numbered A^, A^, B^, B^, as in figure 2. It 

 will be seen that the A^ pieces show an unmistakable electro- 

 negative condition of the apical end. Pieces A^ of stems 1, 4 

 and 5 show the same condition as the A pieces, while the A^ 

 pieces of stems nos. 2 and 3 are doubtful. The B^ pieces also 

 show individual differences, while the B^ pieces of stems nos. 

 1, 3, 4, and 5 show a quite distinct P.D. in the opposite direction. 

 Piece B2 of stem no. 2 is doubtful. 



From the experiments above it appears that the apical or 

 growing end of the stem shows the most distinct chfference of 

 potential. The middle pieces vary more or less, depending upon 

 the individual stem, while the basal pieces tend to have the fall 

 of potential reversed. 



