CEREBRAL LOCALIZATION'. 607 



presides over the muscles of the face. As before, this center may be 

 affected alone or simultaneously with the other. It depends upon the 

 nature of the lesion whether the invasion is sudden, or slow and pro- 

 gressive, ending in feebleness rather than in paralysis. The proximity 

 of the brachial and facial centers explains their apparent solidarity in 

 the normal state, as shown by the grimaces that often accompany vigor- 

 ous use of the arms. It seems as if the second center were stimulated 

 by the activity of the first. We close our enumeration of the centers 

 which the clinic has proved to exist by reference to the center of artic- 

 ulate language, discovered long ago by Broca, which attends to the 

 coordination of phonetic movements. 



We have seen that lesions of the motor region of the brain may be 

 manifested by spasms as well as by paralysis. These monospasms have 

 been long known, but it was Hughlings Jackson who first attributed 

 them to lesions of the motor region of the brain. Prior to this they 

 had been described by Bravais, but he did not seek for their origin or 

 signification. They are localized convulsions, or partial epilepsy, and 

 Hughlings Jackson thinks they are due to nervous tension. Any new 

 excitement added to those already stored up will produce discharge or 

 spasm. Like monoplegia, they may be limited to an arm or leg, or 

 even the face ; but these phenomena ai'e seldom noticed, and we have 

 few observations upon them. When the spasm involves several parts 

 of the body, it always begins at the same point and follows the same 

 order. Dr. Maragliano has made a very interesting study of partial 

 epilepsy, and explained its causes and signification. Both monospasms 

 and monoplegia indicate the same localization of power. 



The sensitive region is found, by experiment, behind the motor 

 centers. While limited lesions of this region often manifest them- 

 selves externally as circumscribed anfesthesia, it sometimes happens 

 that they remain latent when they are seated on only one hemisphere. 

 There is no sign of pathological perturbation, and in this case we seem 

 forced to admit functional substitution, or the possibility of the regu- 

 lar action of two sensitive, homologous regions, notwithstanding the 

 absence of one of the two corresponding cerebral hemispheres. What 

 does this signify ? Must we abandon the doctrine of localization as 

 reo-ards the sensitive centers ? A single center suffice for the two 

 parts of the body ? This anomaly is probably due to insufficient ob- 

 servation. Disease of the cerebral centers may give no further symp- 

 tom than enfeebled sensibility, which might pass unperceived. Lesions 

 of the motor region often result not in total paralysis but in slight 

 paralysis a feebleness and not an abolition of the functions. But 

 there are cases where lesions of the sensitive region are accompanied 

 by less equivocal symptoms, and it is from these that we affirm local- 

 ization. 



Symptoms may be of two orders, according to the nature and the 

 phase of the disease : symptoms of excitation, which produce subjec- 



