NON-MEDULLATED NERVE FIBERS 75 



if we adhere to the long accepted teaching that the axons of the 

 spinal ganglion cells divide dichotomously into central and 

 peripheral fibers. 



2. Axons of the small spinal ganglion cells 



In a paper published in 1898 Dogiel showed that the small 

 cells of the spinal ganglion were associated with non-medullated 

 fibers. He says: 



In addition to their size the only distinction between the cells in 

 question (small cells) and the large cells consists in the fact that from 

 each such cell there always arises a single extremely slender process 

 which remains non-medullated throughout its entire course .... and 

 finally divides in the forms of a T or Y into two slender varicose threads. 

 I have succeeded . . . .in demonstrating that the chief processes of the 

 small cells and the fibers that arise from their division retain the 

 character of non-medullated fibers so far as they can be traced in the 

 ganglion, the dorsal root and toward the point of union of the ventral 

 and dorsal roots. 



In Dogiel's recent book ('08), speaking of the cells of type i, 

 he says that the small cells have non-medullated axons. He 

 also states that the cells of type x are all small and that their 

 axons are all non-medullated. Cajal ('06) working with his 

 silver method, was able to confirm those observations of Dogiel's 

 and to show that the axons of the small cells of the spinal gan- 

 glia are non-medullated and divide in the form of a T or Y into 

 central and peripheral fibers. The axons of the large cells are 

 meduUated. 



3. Observations on the structure and functions of the small cells 



This difference between their axons is only one of the many 

 differences between the large and small cells. Special emphasis 

 has been laid on this point in another paper (Ranson '08) and we 

 need only summarize briefly some of the peculiarities of the small 

 cells and mention some of the theories to which these peculiari- 

 ties have given rise in order to show that the necessity for some 

 explanation of the significance of these little cells has long been 



