CONTROL OF ORGANIC POLARITY 479 



the internode. Internodes from the extreme basal region of the 

 colonies were not used in any of the experiments. 



The above description of the process of regeneration of inter- 

 nodes in the absence of the electric current, shows two im- 

 portant facts : 



1. Isolated internodes possess and retain the original inherent 

 polarity. This polarity manifests itself in the earlier appearance 

 of the hydranth at the apical end of the internode than at the 

 basal end of the same internode. 



2. Normally under the conditions of our observations, a 

 hydranth forms at the basal end of the internode and not a 

 stolon, this was generally true in 90 to 100 per cent of the 

 internode pieces. 



Now, in order to show by means of the electric current that 

 we can control and determine the physiological polarity in an 

 internode according to which morphological polarity will develop, 

 it is necessary to show not only that we can cause a hydranth 

 to appear at the basal end of the internode before the appearance 

 of that at the apical end, but also that the original normally 

 inherent polarity of the internode can be reversed by the electric 

 current, so that it will, for example, produce a stolon where 

 normally a stolon would not have appeared, namely, at the 

 apical end of the internode. 



EXPERIMENTS 



For brevity the experiments reported in this paper are num- 

 bered 1, 2, and 3, without reference to the total number per- 

 formed or order in which they were carried out. Only a total 

 of eight or nine experiments were performed in the limited time 

 available for the work. The results of the experiments not 

 reported differ only from those given in respect to the several 

 effects which different current densities bring about in the 

 regeneration of the piece. If, then, we describe fully the few 

 experiments given, we will have included all the significant 

 effects which appeared in the total number of experiments per- 

 formed. Drawings to show the relative amounts of growth in 

 each piece of all the experiments were made at different times 



