CONTROL OF ORGANIC POLARITY 475 



Therefore, it ought to be possible to influence the polar character 

 of the differentiation in regenerating structures by properly 

 orienting such material in an electric current of proper density. 

 This did prove to be possible, as the experiments below will 

 show. 



METHOD 



The procedure described below was adopted after several 

 attempts to obtain satisfactory experimental conditions in 

 respect to the following: 1) Density of the electric current. 

 2) Aeration of the sea-water. 3) Definite orientation of the 

 regenerating pieces of stem which were generally not more than 

 3 or 4 mm. in length. 4) An arrangement of the electrodes so 

 as to prevent all possibility of products of electrolysis at the 

 electrodes from coming in contact with the regenerating pieces. 

 Figure 2A shows the arrangement. The current was obtained 

 from storage and dry cells giving about twenty volts. The 

 milliammeter, g, and resistance, r, were placed in series. The 

 non-polarizable electrodes were connected to the troughs, as 

 shown in A, by means of cotton dipping into the stream of sea- 

 water which was constantly flowing through the trough from 1. 

 To prevent zinc sulphate from diffusing into the trough, the 

 cotton connections were adjusted to act as siphons. A con- 

 tinuous stream of water flowed from the trough through the 

 cotton. Electrolysis at the electrodes results in a change of 

 resistance and therefore variation in current intensity. To 

 overcome this difficulty, the adjustable resistance, r, was intro- 

 duced. The troughs were made from blocks of hard paraffin 



electrolysis from entering m from the non-polarizable electrodes. A milliam- 

 meter, g, and adjustable resistance, r, are placed in series. The internodes, i, 

 are held in position on the cork plate, k, by the glass rod, h, shown in more detail 

 in B and C. The glass plate, /, covers the trough and thus maintains a con- 

 stant cross-section of the conducting water column. In B is shown a cross 

 section of one of the troughs, in B the capillary glass rod, h, is placed over inter- 

 nodes, i, to hold them in position, details of which are shown in C. A surface 

 view of a gradient trough for obtaining different current densities in the same 

 experiment is shown in D. The arrows indicate the direction of the water 

 current. The positions of the cork strips, k, are such that the current densities 

 at these levels in the trough are as 1 : 5 :\ : J. 



