432 ELIZABETH HOPKINS DUNN 



(dorsal) root and terms them recurrent fibers. He suggests 

 that they afford the basis of the famihar recurrent sensibihty 

 noted by Schiff and Bernard. That is, Sherrington judges the 

 fibers he found to be fibers carrying sensation from the ventral 

 root to the spinal ganglion and thence to the spinal cord. Sher- 

 rington traces the fibers to the dorsal root near the exit of the root 

 i^to the spinal nerve. 



Kidd ('11) has assumed the presence in the ventral root of 

 certain afferent nerve fibers which are supposed to have their 

 perikarya within the spinal cord. Kidd's contention is that 

 a^erent nerve fibers are present in the ventral root of the spinal 

 cord of man and other vertebrates and that their origin lies 

 within the spinal cord from endoneural ganglion cells located in 

 (1) the smaller cells of Clarke's column, (2) in the solitarj^ cells 

 of the dorsal horn, (3) some of the 'middle cells' of the cord, and 

 possibly also (4) some of the cells of the nucleus cuneatus of the 

 bulb. 



Braeunig ('03) noted the existence of early degeneration of 

 certain fibers in the ventral nerve root after section of the dorsal 

 root. Braeunig assumes that the section of the dorsal root may 

 cause degeneration of certain of the motor cells within the spinal 

 cord and of their axis cylinder processes which would be found 

 in the ventral root as efferent fibers. 



In the present investigation the meduUated nerve fibers were 

 followed in serial section through the mass of dorsal root fibers 

 into the substance of the ganglion and to a part of the ganglion 

 much nearer to the central end of the ganglion than in the case 

 of Sherrington's group of nerve fibers. For this reason I am 

 inclined to interpret such fibers as central, not as peripheral 

 processes of the spinal ganglion neurones. Their location in the 

 ventral root at its central end must also be taken into consideration. 

 If the function of these fibers is the carrying of sensory impressions 

 from the substance of the spinal cord or from the meninges, one 

 would expect to find them near the enveloping membranes of 

 the root. 



These fibers cannot be of the type to which Kidd refers. If 

 they were processes of endoneural cells which left the spinal 



