304 Journal of Comparative Neurology. 



only on motion as awkwardness, the cerebellar showing more- 

 over the typical dizzin^ ss, the tabetic ataxia characterized es- 

 pecially b}- abolition of the reflexes in the parts affected and by 

 defects of sensibility, and the pseudo-tabes by a different clini- 

 cal picture, and especially combination of sensory defects with 

 motor disorders of the ' peripheral ' type. 



General pathology of the nervous system teaches us to 

 distinguish focal lesions and diffuse affections. My own point 

 of view would lead me to insert affections of special mechan-. 

 istns (writers' cramp and other localized disorders of limited, 

 and therefore localized, mechanisms). For the usual purposes 

 we can get along with the two classes mentioned. The gen- 

 eral advice is, that a symptom-complex which can be explained 

 by a lesion of one point in the nervous system, should be re- 

 ferred to it ; symptom-complexes explicable by two focal le- 

 sions only are to be taken with caution, and if numerous lesions 

 would be necessary for the explanation of the symptoms, we 

 do best to think of the possibility of general disorders (toxic, 

 infections or asthenic). Where no evidence is present of a 

 segmental affection but a whole side or the face or arm or leg 

 alone show the sympton-complex of the cerebral-efferent sys- 

 tem, we are almost certainly dealing with a lesion in the supra- 

 segmental region, the motor region or the internal capsule. A 

 concomitant disorder of the stereognostic sensibility would 

 speak in favor of the cortical seat of the lesion ; a purely mo- 

 tor hemiplegia for an affection of the internal capsule, etc. In 

 other words, the condition of the movements and the muscles 

 prove the existence of a lesion of the cerebral efferent system ; 

 but the question ' where is the lesion located zvithin this sys- 

 tem ' must be settled by concomitant symptoms. Thus, we 

 make our diagnosis of the rare hemiplegia alternans on the 

 ground of the symptom-complex hemiplegia plus segmental 

 affection of the third or seventh nerve, as the case may be. 



Or we find a spastic paralysis of both legs. It may be 

 due to a transverse lesion, in which case we get also certain 

 segmental symptoms, or it may be pure * lateral sclerosis * as 



