396 



THE NERVOUS SYSTEM. 



have been obtained by Schiefferdecker * in dogs after section of the 

 spinal cord in the dorsal region, with consequent paralysis of the poste- 

 rior limbs. The degeneration of the pyramidal tracts in these cases 

 was constant, and always in a descending direction, from the point of 

 section to the lower extremity of the cord. 



Finally, in the experiments of Woroschilofff on the rabbit, the func- 

 tion of the pyramidal tracts in the lateral columns was investigated 

 by partial sections of the spinal cord in the dorsal region. The main 

 results of these experiments are as follows : 



PARTIAL SECTIONS OF SPINAL CORD OF RABBIT, IN LOWER DORSAL REGION. A, B, C. Without 

 Paralysis. D, E, F. With Paralysis. A. Section of Posterior Columns. B. Section of Anterior 

 and Posterior Columns and Gray Substance. C. Section of Anterior half of Cord. After all 

 these sections the animal uses his hind legs freely in locomotion. D. Section of the entire cord 

 except left lateral column ; paralysis of right hind leg, preservation of motion in left. E. Section 

 of both lateral columns ; paralysis of both hind legs. F. Section of posterior half of cord ; paralysis 

 of both hind legs. (Woroschilotf.) 



Voluntary motion in the posterior limbs remains unimpaired after 

 1st, Section of both posterior columns (Fig. 107, A) ; 2d ; Section of both 

 anterior and posterior columns and the gray substance (B) ; and 3d, 

 Section of the anterior half of the cord on both sides (C). That is, 

 every part of the cord, excepting the posterior half of the lateral col- 

 umns, may be divided in the dorsal region without causing paralysis 

 of the hind limbs. On the other hand this paralysis is produced by 

 section of both lateral halves of the cord outside the gray substance 

 (E), and by section of the posterior half of the cord on both sides (F) ; 

 and lastly, division of the whole cord excepting one lateral column (D), 

 leaves the hind limb on that side capable of movement while the 

 opposite limb is paralyzed. The transmission of voluntary impulses 

 in the spinal cord takes place therefore through the pyramidal tracts, 



* Archiv fiir pathologische Anatomie und Physiologie. Berlin, 1876. Band 

 Ixvii., p. 542. 



f Arbeiten aus der physiologischen Anstalt zu Leipzig. Jahrgang, 1874. Leipzig, 

 1875, p. 99. 



