THE SPINAL CORD. 669 



appear to have conclusively established that the gray matter, as well as the 

 white, possesses conducting powers; as we might indeed anticipate from the 

 circumstance, that it contains a large amount of the fibrous form of nerve-tissue, 

 and that the commissural connection between the two lateral halves of the Cord 

 is established (according to Mr. J. L. Clarke, 696) by its gray substance 

 alone. That a ready transverse communication exists, is proved not merely 

 by the fact that an impression made upon a nerve of one side will very com- 

 monly excite reflex movements on both; but also by the experiment of com- 

 pletely dividing one-half of the cord as far as the median line, and dividing the 

 other half to the same extent a short distance below the first section ; for this 

 operation does interrupt the transmission of sensory impressions, although it 

 seems doubtful whether motor influences can be thus propagated. 1 The experi- 

 mental results of Stilling, 3 again, are on the whole in harmony with the pre- 

 ceding; but he lays yet greater stress than Van Deen on the importance of the 

 gray matter to even the conductive power of the white. These deductions, 

 however, are strongly opposed by Longet, who affirms that he could never ob- 

 tain any evidence either of sensibility or of motor power, on irritating the gray 

 substance alone by the electric current; and that, on the other hand, the entire 

 destruction of the gray matter for a considerable length, by means of a rod 

 introduced into the interior of the Cord, did not seem in any degree to impair 

 the conducting power of its columns. It must be borne in mind, however, that 

 there are numerous pathological phenomena, which it is very difficult to recon- 

 cile with the foregoing conclusions regarding the relative functions of the 

 anterior and posterior columns of the Spinal Cord; cases having occurred, in 

 which complete destruction of the anterior columns appeared to have taken 

 place, without loss of voluntary motion in the parts below ; whilst a similar 

 destruction of the posterior columns has occurred without corresponding lesion 

 of sensibility. 3 But it must be borne in mind that we are still far from having 

 an accurate knowledge of the degree of structural change in the nervous centres, 

 which is incompatible with the continued performance of their functions; and 

 that there are instances in which the whole thickness of the cord has under- 

 gone softening and apparent disintegration, without the destruction of the 

 functional connection between the Encephalon and the parts below the seat of 

 the disease. 4 



1 A case is cited by Longet from Begin, in which a man was stabbed at the back of the 

 neck, the point of the knife passing obliquely forwards between the sixth and seventh 

 cervical vertebrae, dividing the antero-lateral and anterior columns of the Spinal Cord on 

 the right side. He survived the injury six days ; and suffered from complete paralysis of 

 motion of the corresponding lower extremity, with incomplete paralysis of motion of the 

 right arm ; the sensibility remaining perfect. This case seems to show that the Will has 

 no power to direct its motor impulses across the cord ; since the parts deriving their nerves 

 from the part of the cord below the partial section were entirely withdrawn from its in- 

 fluence. 



2 " Untersuchungen iiber die Functionen des Ruckenmarks und die Nerven," Leipzig, 

 1842. 



3 See especially the case recorded by Mr. Stanley in "Med.-Chir. Transact.," vol. xxiii. 

 and by Dr. Webster, Op. cit., vol. xxvi. 



4 See, for example, the case of "Softening of the Spinal Marrow," recorded by Dr. 

 Nairne in the "Med.-Chir. Trans.," vol. xxxiv. ; in which a portion of the Cord at least 

 an inch long, situated opposite the third and fourth dorsal vertebrae, was " so soft that the 

 slightest pressure of the finger broke it up," being nearly in a fluid state through its 

 whole thickness ; yet the patient felt pain in his lower limbs, showing that the power of 

 upward transmission remained ; and, although he had lost all voluntary control over the 

 muscles of the lower part of the body, yet they were affected with incessant choreic move- 

 ment (which, as will be shown hereafter, Sect. 7, appears to originate in the Sensory 

 Ganglia), and these movements were affected in such a marked manner by emotions, as 

 plainly to indicate a downward transmission of motor power. 



