580 PHYSIOLOGY CHAP. 



regions, as the cortex of the occipital lobe, may also produce 

 epilepsy (Unverricht, Franqois-Franck), and it might be supposed, 

 and was in fact assumed by some, that in these cases the epileptic 

 attack develops independently of the motor area. 



But these two groups of arguments lose all value as against 

 the origin of epilepsy in the cortical motor area, if we admit that 

 in all these cases the state of excitation started in a sensory area 

 must necessarily be transmitted to the motor region before the 

 epileptic attack can occur. This is directly proved by the work 

 of Rosenbach and Danillo ; they found that electrical stimulation 

 of the occipital lobe no longer produced an epileptic attack after 

 the entire motor area of the homonymous side had been destroyed, 

 or if a narrow band of grey matter were excised between the motor 

 area and the excited occipital area. They further found that if 

 the excited occipital area were separated by an incision after the 

 attack had already set in, this did not cease, though it was always 

 arrested if the motor area was removed at the proper time. 



(/3) Complete, bilateral epileptic attacks can be evoked by 

 exciting the motor area of one side after previous destruction of 

 the motor area of the opposite side (Albertoni, Franqois-Franck 

 and Pitres). But this fact does not controvert the cortical origin 

 of epilepsy, and even confirms it, as it proves that in the bilateral 

 spread of the epileptic attack the epileptogenous excitation often, 

 if not always, diffuses to the motor centres of the bulb (or bulbo- 

 spinal tract), which may be considered as the accessory, comple- 

 mentary, though indispensable factor. TJnverricht's observations 

 agree with this interpretation. He saw that the bilateral attack 

 caused by excitation of the motor zone on one side is frequently 

 not of equal intensity on the two sides. While the muscles of the 

 side opposite that excited are in clonic convulsions the muscles of 

 the same side are in tonic contraction, or contract clonically in 

 the same rhythm, but less strongly than those of the opposite side. 

 From this he concluded that the essential part of the epileptic 

 attack consists in primary muscular convulsions, the indispensable 

 conditions of its appearance being the integrity of the cerebral 

 motor area. 



(y) A complete section of the corpus callosum of the cat does 

 not prevent the onset of a bilateral epileptic attack after electric 

 stimulation of the motor area of one side (Franqois-Franck and 

 Pitres). But this fact does not positively exclude the interpre- 

 tation offered by Bubnoff and Heidenhain, that the excitation 

 may be transmitted from one hemisphere to the other, since the 

 commissural fibres of the corpus callosum have not been proved 

 to be the sole and exclusive connecting paths between the grey 

 matter of the two hemispheres. In any case the bilateral spread 

 of the fit may be explained by the active intervention, in a 

 secondary and subordinate manner, of the bulbo-spinal centres. 



