x THE FORE-BRAIN 577 



excitation of the motor area. They observed that the attack con- 

 sists of two phases, a tonic and a clonic stage. As shown in Fig. 

 294, the tonic phase persists, and reaches its maximum after the 

 cessation of tetanisation ; the clouic phase lasts longer, and is 

 characterised by violent, but less frequent and irregular, muscular 

 contractions. The tonic phase may be altogether absent, especi- 

 ally if the animal is deeply under the anaesthetic ; then the con- 

 tractions are very pronounced, and the intervals between them 

 increase as the muscle relaxes. 



These facts were confirmed by Horsley and Schafer in both 

 dogs and monkeys. According to Charcot partial epileptic attacks, 

 which he terms vibratory, because they consist of simple clonic 

 spasms definitely separated from one another, can be observed in 

 man. In idiopathic epilepsy, on the contrary, according to Brown- 

 Sequard, the initial tonic phase is never absent. 



We have already considered the organic changes (respiratory, 

 cardiac, vascular, secretory, visceral, etc.) which accompany epi- 

 leptic seizures. FranQois-Frauck first analysed these minutely by 

 means of the graphic method, and demonstrated that the epileptic 

 organic effects can be elicited without convulsions of the voluntary 

 muscles when the cerebral cortex of a curarised dog is electrically 

 stimulated with strong currents, under artificial respiration. 



Besides faradisation of the brain, the development of spontaneous 

 epileptic fits may be observed in animals in which a part of the 

 cortex has been destroyed. This fact affords experimental con- 

 firmation of Jackson's clinical observations. The first four cases 

 of epilepsy in dogs after extirpation of part of the motor area were 

 described by Hitzig. He did not discuss the pathogenesis of 

 epilepsy ; but confined himself to the simple statement that lesions 

 of the cerebral cortex may induce epilepsy. 



While experimenting on the brain, we frequently had oppor- 

 tunities of observing various forms of epileptic convulsions which 

 developed spontaneously, under different conditions, in dogs and 

 monkeys after previous operations on the cerebral cortex, and are 

 significant in the pathogenesis of epilepsy. We published a 

 Memoir in 1878 in which after a critical examination of the 

 different cases of epilepsy due to lesions of the cortex we put 

 forward a general theory of the cortical origin of epilepsy, whether 

 Jacksonian or idiopathic, and stated that the motor area of the 

 cerebral cortex represents the central organ of epileptic con- 

 vulsions. Direct or indirect excitation of this area due to any 

 cause is the essential factor of the epileptic seizure. The excita- 

 tion of the bulb is probably an accessory, complementary factor, 

 which is not indispensable. Shortly stated, the following are the 

 arguments in favour of, and opposed to, this theory : 



(a) When the epilepsy develops in animals after partial 

 destruction of the motor area on one side the tonic-clonic con- 



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