ELECTRICAL POLARITY IN OBELI A 493 



which are everywhere a common fundamental characteristic of 

 the in(U\ickial in organic nature, whether it be a cell, group of 

 cells, or whole organism. 



There is another significant point to which I wish to call atten- 

 tion. If cells, cell groups, and individuals, e.g., polyps in a 

 structurally and physiologically correlated system like Obelia, 

 possess an inherent mechanism for establishing directed electro- 

 motive forces within themselves in relation to their structural 

 or functional polarities, then it will be clear that here we may 

 have a normal electrical mechanism which may serve as a de- 

 termining factor in the process of orientation of cells with re- 

 spect to one another during embryogeny and regeneration. 

 I do not wish to carry this line of reasoning farther in this paper 

 than to suggest the possibilities. In following papers will be 

 presented experimental evidence relative to this question. 



Because of the nature of the experimental method employed 

 in the experiments above, it was necessary to manipulate the 

 stems and pieces in air. This obviously limited the degree of 

 accuracy of the results A further detailed and quantitative 

 study of the phenomena will be undertaken when appropriate 

 and sufficiently accurate methods for measurement have been 

 devised. 



SUMMARY 



1. A definite difi'erence of electrical potential occurs in the 

 stem of the colony of Obelia. This confirms the conclusion 

 arrived at by means of a different method in the preceding paper, 

 that an electrical polarity is one primary associated condition 

 for the development of morphological polarity. 



2. The electrical polarity in the stem of Obelia is associated 

 with the living tissue of the coenosarc and does not originate in 

 any other structure of the stem for no potential difference occurs 

 in the following: a) Stems left to die and macerate in sea-water; 

 h) stems from which the living tissue has been removed mechani- 

 cally, and, c) stems in which the living tissue has been killed by 

 chloroform. 



3. The potential difference in the stem is not associated directly 

 or simply with the mechanical injury due to cutting, and there- 



