234 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



slightly, and in the latter case the hyperesthesia may appear on either or 

 both sides. 



(c) The prominent and almost constant sensory symptom is the contra- 

 lateral loss of the sensation lor pain and temperature. 



On the basis of a case 1 in which the lateral columns of the cord and the 

 gray matter of both horns on the same side were the seat of damage, and in 

 which there was a total loss of pain on the opposite side of the body without 

 impairment of tactile sensibility, it may be inferred that the pain-impulses 

 cross soon after entering the cord, and pass cephalad by some path lying 

 within the damaged area. 



A second case 2 is recorded in which a stab-wound divided all of one-half 

 of the cord pins the dorsal column of the other half. There was here a loss 

 of sensibility to pain on the side opposite the lesion, together with the loss of 

 tactile sensibility on both sides, pointing, therefore, to the dorsal columns as 

 the paths for the tactile impulses. The experiments on the lower animals 

 contradict this conclusion. 



The observations of Turner 3 on monkeys, in which hemisection of the 

 cord had been made in the lumbar and thoracic regions indicate that all sen- 

 sory impulses cross immediately after entering the cord, yet section in the 

 cervical region showed that the impulses roused by touching the skin pass in 

 part on the same side of the cord as the section, the other sensory impulses 

 being, however, completely crossed. 



On the other hand, from his work on hemisection of the thoracic cord of 

 the monkey at different levels/ Mott found the disturbance of sensibility of 

 all forms mainly on the side of the section. 



Hemisection of the Cord. — From experiments on monkeys and a few 

 cats Schafer reports the following physiological changes after hemisection of 

 the spinal cord in animals : " In the first few days complete motor paralysis 

 of all part- supplied with nerves below the section. The limb or limbs on 

 the paralyzed side swollen and warm (vasomotor paralysis) and lessened out- 

 flow of lymph and the skin dry (diminution of sweat). Knee-jerk exag- 

 gerated. Sensation not lost on the same side as the lesion, but at first appears 

 dulled. (There is a difficulty in arriving at a clear decision on account of 

 the motor paralysis rendering the animal unable to move the limb.) After 

 a few days, unmistakable signs of feeling and localizing even a slight touch, 

 and this long before the motor paralysis has passed oil'. The animals gener- 

 ally disregard a clamp-clip on the skin of the paralyzed limb, but not always ; 

 this phenomenon usually lasts until the return of movement in the muscles 

 of the limb.' 1 I have seen no signs of paralysis cither motor or sensory on 



'Gowers: Clinical Society's Transactions, 1878, vol. xi. 



2 Muller : /<"' itri'n/i -in- jiniliiiliii/ischi Aii'iiniiiii imil I'/niswIogie dea Riickenmarkes, Leipzig, 1871. 



3 Brain, 1891. ' Mott : Journal of Physiology, 1891, vol. xvii. 



5 It will be seen that my observations on this point agree generally with those of Mott 

 (Phil. Trims. B. 1892), although my conclusions are somewhat different. Mott, in my opinion, 

 lays too much stress on the results of the clip test (Schafer). 



