418 EFFECT OF IRRITATION OF A POLARIZED NERVE. 



abolisli the pain according to the degree of pressure. Applying the 

 constant pressure to other portions of the body will oftentimes relieve 

 or increase the pain. Under these circumstances the constant current 

 is replaced by the pressure. 



The experiments are again of importance in explaining the varying 

 symptoms following a hemorrhage into a given portion of the brain, and 

 also in explaining why a lesion in the neighborhood of the corpus stria- 

 tum in man should produce hemiplegia of the opposite limbs, while its 

 destruction in man or any of the mammals is never followed by this 

 symptom. Again, it will explain why we have sometimes paralysis and 

 at other times convidsions, or in still other cases paralysis and convul- 

 sions in the same person from the same brain lesion. 



The fact that cerebral-hemiijlegia had never been i^roduced in animals 

 attracted my attention four years ago. Since that time I have constantly 

 endeavored to produce this symptom in animals, but until recently with 

 no success. 



After having found that section of the whole brain immediately above 

 the corpora quadrigemina is not followed by abolition of the voluntary 

 movements,* it occurred to me that perhaps Brown-Sequard's theory 

 was the true one, and that the paralysis resulting from brain lesions 

 was due to the irritation and not to the destruction of the nerve tubules in 

 this organ. If this be so, an irritating substance injected into the brain 

 in the vicinity of the corpus striatum would produce paralysis of the 

 oi^posite side of the body. I tried this by injecting aqua ammonia, but 

 in the first experiments injected too much, and the animals died in con- 

 vulsions or coma. Later, by using an injection of l-oni, I was, in several 

 dogs and cats, able to produce hemiplegia on the side opposite to that 

 on which the injection was made. The animals, in attempting to walk, 

 dragged their limbs as in true hemiplegia. Even in them, however, 

 under unusual strong excitement, the paralyzed limbs were moved.t 

 This result could not have been due to pressure on distant parts, as the 

 injection of a similar quantity of water failed to produce the same 

 effect. 



These experiments with ammonia were sufficient to show that hemi- 

 plegia can be produced in animals by the injection of irritating sub- 

 stances in the neighborhood of the corpus striatum. The same effect 



*A most interesting case is reported by Dr. Harlow (Boston Medical and Surgical 

 Journal, December 13, 1848), in wliicb the portions of the brain frequently considered 

 as presiding over volitional movements were destroyed by a tamping-iron being driven 

 tbrougb the skull. The patient lived many years after the injury was received. No 

 signs of paralysis were manifest. 



Another case is reported by Dr. Folsom (Pacific Medical and Surgical Journal, May, 

 1869), where a longitudinal hemi-section of the brain, extending nearly, if not quite, 

 to the base of this organ, was made by the patient falling against a circular-saw 

 revolving about two thousand times a minute. The man recovered without paralysis. 



t Carpenter (Physiology, 1855, note on page 635) reports similar phenomena occur- 

 ing in a man. Abercrombie (On the Brain), Wicke (Die Grossen Veits-Tanzele), and 

 other authors report similar cases. 



