240 



Papers from the Department of Marine Biology. 



the axone leaving from the ventral surface. So that it may be stated 

 that in cases of orientation the plasmosome is not oriented toward the 

 axone or in the structural (physiological?) axis of the cell, but that it 

 is always oriented in the dorso-ventral axis of the cell. Of course, the 

 dorso-ventral axis might be a physiological axis, but its independence 

 of the structural axis as formed by a line drawn through the majority 

 of the dendrites, the nucleus, and the axone, would still require an 

 explanation of why it was dorso-ventral. It could only exist in this 

 direction to accommodate the factors of gravity or the electric current, 

 and we shall see that in Torpedo it does not do this. It thus seems to 

 the writer that the orientation, where found, is a more or less perma- 

 nent condition, persisting over a considerable period of the animal's life. 



FIG. 5. Diagram of form of electric lobes as seen in transverse section, with several 

 enlarged outlines of a few cells on right that show how the neurite may arise 

 from any surface of the cell and how the orientation of the plasmosome is 

 always independent of this factor. Nuclei alone shown on left. 



The fifth hypothesis, that this more or less permanent orientation 

 is of value to the physiological activities of the cell, is a difficult one to 

 discuss. Since it appears to be much more profitable to consider it in 

 a paper on the more highly differentiated electric nerve-cell of Tetro- 

 narce occidentals that is shortly to appear, it will be dismissed here with 

 the remark that no strong evidence has been produced to show that 

 such relation exists. Against it appear several facts: 



First, the condition mentioned above, that the axis of orientation 

 of the plasmosome does not correspond in all cases to the functional 

 axis of the cell, would seem to indicate this. It might be assumed that 

 any physiological action taking place in a definite direction would 



