866 THE SPINAL CORD. 



far as could be judged all parts postjacent to the section. Further 

 experiments of this kind l on the dog show that when in the hindmost 

 thoracic region an interval of some six or seven spinal segments is 

 allowed between the semisections, recovery of motility of the hind-limbs 

 in walking and progression may ultimately, although long delayed, 

 be almost as complete as after single semisection. Restoration of 

 sensitivity is longer delayed and less perfect. The incipient effect 

 of the second semisection is to destroy locomotor and volitional 

 motility and sentient power altogether in both hind-limbs. In one 

 experiment three semisections were successfully accomplished, the 

 foremost at the highest lumbar segment ; the second, three spinal 

 segments lower and on the opposite side ; the third, the final, on the 

 same side as the first and six spinal segments behind it. The power to 

 stand was in time recovered. The strongest stimuli to the hind-limbs 

 failed to evoke any sign of pain, as also did faradisation of the sciatic 

 nerve. Faradisation of the spinal cord in the cervical region excited no 

 movement in the hind-limbs. On more than one occasion irritation of 

 the skin of the neck evoked scratching movements of the hind-paw. 

 But I have myself seen this remarkable phenomenon after total transec- 

 tion at the eighth cervical level ; the movement in front of the spinal 

 severance is clearly mechanically conveyed to parts behind the lesion, 

 and there in turn excites the spinal " scratch " reflex. 



The conditions produced by spinal semisection have been studied 

 recently in the ape (Mott, 2 W. A. Turner, 3 Schafer 4 ). The seat of the 

 lesion has been cervical, thoracic, or lumbar. Mott found impairment of 

 " volitional " movement in the homonymous limb or limbs, but with time 

 some restoration, just as noted in the dog, 5 especially of associated 

 movements. The defect of sentient power appeared at first considerable 

 when tested by the application of a spring clip to the homonymous 

 side ; but there was much less impairment for tactual, pricking, and 

 thermal stimuli. With the recovery of movement there gradually 

 ensued considerable recovery of response to the pressure of a clip. 6 

 Muscular sense was thought to be impaired on the homonymous side. 

 Mott also noted allochiria ; 7 a spring clip applied on the homonymous 

 side occasionally directed attention not to the place stimulated, but 

 to one symmetrically situated on the opposite side of the body. 

 As to the effects of semisection, there obtained, for some years 

 after publication of observations by Brown-Sequard, 8 a view fraught 

 with practical importance from the support it seemed to obtain from 

 clinical observations. It was held by Brown-Sequard that the path 

 subserving cutaneous sensation ascends the spinal cord entirely contra- 

 lateral to the initiating sense organs, the decussation of the afferent 

 channels occurring soon after their entrance in the cord. Paralysis of 

 intended movement without cutaneous anaesthesia on the one side, and 

 on the opposite cutaneous anaesthesia without volitional paralysis, is 



1 Osawa, "Inaug. Diss.," Strassburg (Goltz's laboratory), 1882; Borgherini, "Beitr. z. 

 Kennt. d. Leitungsb. im Riickenmark, " Wien, 1886. 



2 Phil. Trans., London, 1892. 3 Brain, London, 1892, vol. xv. 



4 "Proc. Physiol. Soc.," March 1899, Journ. Physiol., Cambridge and London, vol. 

 xxiv. p. xxii. 



5 Eigenbrodt, op. cit., 1849 ; v. Bezold, op. cit., 1859 ; Weiss, op. cit., 1880; Homen, 

 op. cit., 1885. 



6 Cf. on this point, Schafer, Journ. Physiol., Cambridge and London, 1898, vol. xxiv. 



7 See Obersteiner, Brain, London, 1882, vol. iv. p. 153. 



8 Compt. rend. Soc. de biol., Paris, 1850, tome i. p. 192. 



