THE ROOTS OF THE PERIPHERAL NERVES, ETC. 171 



posture in cerebellar disease, but in tabes dorsalis, where the 

 highest decrees of ataxy are sometimes present, the fibres of the 

 posterior and of the vesicular columns are degenerated : the 

 continuity of the tracts to the cerebellum is broken. 



The anatomy of the spinal cord, so far as it could be ascertained microscopi- 

 cally, was described by Burdach, Sommeriug, and F. Arnold. Bellinger! first 

 discovered the connection existing between the anterior roots and the gray matter 

 of the anterior horns, while Grainger rendered the same service with respect to 

 the posterior roots and the posterior horns. The finer structure of the spinal cord, 

 however, was first discovered by B. Stilling, and after him additional light was 

 thrown on the matter by Kolliker, Goll, Deiters, Gerlach, Clarke, and others. 

 "We owe our knowledge of the -course- of fibres in the white substance principally 

 to the works of Turk, Flechsig, Charcot, and Gowers. 



The picture which I have given you to-day of the most im- 

 portant tracts of fibres in the spinal cord might be made much 

 more complete, might be improved by many highly interesting 

 details. We have touched, however, upon many points where 

 our knowledge is uncertain, so that a faithful adherence to the 

 object of these lectures will compel us to stop at this place, 

 where the lack of known details and the conflicting opinions of 

 authors prevent us from laying before the student clear and 

 definite views. 



In the preface to his great work on the structure of the 

 spinal cord, Stilling says, " We must not, to borrow the lan- 

 guage of the distinguished Burdach, forget that in investigating 

 the spinal cord we are traveling through a wonderland of which 

 we have no accurate knowledge. We can only turn our atten- 

 tion to the rivers and mountains in order to get a general idea 

 of the whole, and must leave it to those who follow to trace up 

 and map out the minor features of the landscape." Thirty years 

 have passed away since this preface was sent forth into the world 

 with a book richer in material than any ever before presented to 

 anatomical science. We are still far from the goal, and it will 

 be long before that perfect map can be drawn of which both 

 Stilling and Burdach dreamed. 



