210 STUDIES IN ELECTRO-PHYSIOLOGY: 



I am encouraged in this opinion by a careful study of 

 the structure of unipolar cells and by other considerations. 

 To my mind it would appear that the structure of even the 

 unipolar cell is not simple but complex. It seems to be 

 circular in form throughout to be, in fact, a series of rings ; 

 and while the microscope has not, so far, given us the 

 needful detail, it does not call for an undue stretch of the 

 imagination to believe that it may, possibly, be composed of 

 a series of Leyden jars ; that is to say, circular layers of 

 conducting substances with non-conducting substances 

 between them, and that such layers, like the sarcomeres, 

 are insulated from each other and are in connection with 

 certain assigned nerve-fibres or fibrils. In such case we 

 can conceive in a multipolar cell the impulse being given, 

 as a whole, from a principal central system, or, individually* 

 to any dendron or branch circuit. 



Since writing the foregoing my attention has been 

 drawn to an illustration in Haeckel's Evolution of Man 

 (taken from Max Schultze) of a multipolar cell from the 

 brain of an electric fish, and as it seems to confirm my 

 theory I reproduce it. (Fig. 115.) 



Reverting to the typical multipolar cell of the spinal 

 cord, and at the risk of repetition, I must remind my 

 readers that the axis-cylinder process itself invariably 

 gives off side branches or collaterals, which pass into the 

 adjacent nerve- tissue. " The axis-cylinder then acquires 

 the sheaths, and thus is converted into a nerve-fibre. 

 This nerve-fibre sometimes, as in the nerve-centres after a 

 more or less extended course, breaks up into a terminal 

 arborescence enveloping other nerve-cells ; the collaterals 

 also terminate in a similar way ... all ultimately ter- 

 minate in an arborescence of fibrils in various end-organs 

 (end-plates, muscle-spindles, etc.)." 



Furthermore, " each nerve-unit (cell, plus branches of 

 both kinds) is anatomically independent of every other 



