The Cerebrum. 429 



sible that the cause is some disease of the optic nerve, it- 

 self, in the orbit or in front of the optic chiasm. 



Focal Symptoms. When the lesion is confined to 

 the cortex it may cause such localized symptoms as par- 

 alysis of the opposite hand, or arm or leg, etc., and, in ad- 

 dition, when the cortex alone is affected, we may have 

 Jacksonian epilepsy, i.e., spasms limited to one particular 

 part, such as the thumb, hand, etc., or the convulsive 

 Seizure may start in some such area and spread to other 

 regions, as, for instance, beginning in the finger, it may 

 spread to the hand, then the arm or leg, thus radiating 

 from the primary focus just as the ripples, that follow a 

 stone thrown on the surface of a pond, radiate from a 

 centre, but if the growth or blood clot affects the internal 

 capsule, then, because of the narrow area through which 

 all of the fibres pass, a very small lesion will likely 

 produce widespread disturbance of motion and sensation. 



Tumor of the frontal lobe, or the so-called "silent re- 

 gion," is associated with changes in the disposition of the 

 patient, such as irritability, stupidity, etc. No motor par- 

 alyses result, at first, unless the posterior part of the third 

 frontal or the ascending frontal convolutions are com- 

 pressed. When the tumor involves the third frontal, or 

 Broca's convolution, there is motor aphasia and agraphia, 

 i.e., the patient can neither give utterance to his ideas in 

 words or in writing. 



Motor Areas. A tumor situated here may produce 

 symptoms of paralysis of that part of the body presided 

 over by the motor centres, already mentioned, and is gen- 

 erally associated with Jacksonian epilepsy. It is thought 

 that paralysis unassociated with this form of epilepsy is 

 dependent on a lesion situated deeper in the cerebral tissue, 

 i.e., beneath the cortex, and, therefore, affecting the pro- 

 jection fibres from these" centres. 



