1863.] 569 



III. " On the Structure of the so-called Apolar, Unipolar, and 

 Bipolar Nerve-cells of the Frog." By LIONEL BEALE, M.B., 

 F.R.S., F.R.C.P., Professor of Physiology and of General 

 and Morbid Anatomy in King's College, London, and Phy- 

 sician to King's College Hospital. Received May 7, 1863. 



(Abstract.) 



The author adverts to the opinion generally received with regard 

 to the existence of apolar, unipolar, bipolar, and multipolar nerve- 

 cells, and observes that if cells having such very diiferent relations 

 to the nerve-fibres they are supposed to influence, as apolar, unipolar, 

 and multipolar cells, do actually exist, as many different kinds of 

 action must be admitted. For it is hardly likely that a nerve-cell 

 unconnected with any fibre can affect the fibres at a distance from it 

 in the same way as a cell acts upon fibres which are in structural 

 continuity with it. Neither is it probable that a cell with but one 

 fibre proceeding from it can constitute an organ which acts upon the 

 same principle as the cell from which two or more fibres proceed. 

 If no fibre, or but one fibre proceeds from certain cells, the formation 

 of complete^nervous circuits, at least in these instances, is impossible ; 

 and if it be admitted that circuits do not exist in every case, a strong 

 argument is advanced against the existence of such complete circuits 

 as a necessary or fundamental condition of a complete nervous ap- 

 paratus. But if it can be shown, on the other hand, as the author 

 maintains is the case, that all the supposed apolar and unipolar cells 

 have at least two fibres proceeding from them, the fact must be 

 accepted in favour of the view that such complete circuits may exist, 

 while the fact that the fibres connected with many cells have been 

 seen to proceed in opposite directions some distance after leaving the 

 cell, is a very strong argument in favour of such general inference, 

 and at the same time an explanation of many arrangements which are 

 observed constantly in connexion with nerve-fibres in various tissues. 



Many observers have described apolar and unipolar cells in ganglia 

 in different parts of the frog. The author, on the other hand, has 

 failed to discover any apolar or unipolar cells in this or in any other 

 animal, and considers that the apparent absence of fibres, and the 

 presence of one fibre only in connexion with a cell, result from the 

 defective modes of preparation generally employed. He maintains 



