344 PHYSIOLOGY CHAP. 



The experimental basis of this theory consisted in the fact that 

 after hemisection of the cord there is, according to Brown-Sequard, 

 direct motor and crossed sensory paralysis. The former is asso- 

 ciated with slight paralysis of the opposite side ; the latter is 

 accompanied not by hypoaesthesia, but by hyperaesthesia on the 

 side of the section. Many clinical cases of unilateral spinal lesions 

 confirm the results of these hemisection experiments performed on 

 various vertebrates. 



But it can be objected to Brown-Sequard's experimental results 

 that the animals were under observation for too short a time : 

 that the sensory changes was frequently tested directly after a 

 severe operative trauma ; that there was no microscopic control of 

 the operations ; lastly, that Brown-Sequard's own description of 

 some of the results of his experiments contradict his conclusions, 

 and rather suggest that each half of the cord contains sensory 

 fibres from both halves of the body. It is evident that he allowed 

 himself to be influenced in his experimental observations by the 

 preconceived ideas which he had formed from his clinical observa- 

 tions. The latter, again, are far from invariably confirming his 

 conclusions, and in many cases the seat of the lesion has not been 

 exactly localised by anatomical examination. 



Schiff, too, occupied himself in detail with the effects of spinal 

 hemisection. In his experimental observations (as we learn from 

 his most reliable pupil and successor A. Herzen) he was always 

 guided by the following rules : 



(1) If a function is found to persist immediately, or a few 

 minutes or hours, after the transection of a part of the cord, this 

 is a definite proof that it is independent of the part divided, and 

 is connected with other parts that have not been injured. 



(2) If under these conditions there is a loss of function, this 

 does not prove relation between this function and the injured part, 

 unless the loss persist for weeks and months after the operation, 

 till cicatrisation is complete, the effect of shock entirely worn off, 

 and the animal as far recovered as the operative lesion permits. 



Under these irreproachable criteria, Schiff arrived at the 

 following results from his experiments on unilateral transection 

 of the cord : 



(a) At whatever level one half of the cord is divided, a series 

 of phenomena, some transitory, others permanent, can be seen. 

 The former consist in a diminution of pain sensibility on the 

 opposite side, which may amount to total analgesia ; various motor 

 disturbances on both sides ; frequently hyperaesthesia to pain of 

 the injured side, associated with vascular dilatation. The only 

 permanent symptom is the abolition of tactile sensibility on the 

 side of the lesion in all the more caudal parts. 



(6) After transection of the whole spinal cord with the 

 exception of the posterior columns in the thoracic region, there is 



