Etioloj,ry. ' 7.(37 



influence on the rnnip and tlie liind qnarters, an epileptic attack 

 in the domestic animals must arise chiefly in the cortex of the 

 brain, passing over the motor centers by way of the extra pyram- 

 idal tracts or in these latter structures themselves. 



In dogs, faradisation of definite areas of the cortex causes spasms which are 

 quite like typical epileptic attaclcs. The spasms at first occur in the parts of the 

 body whieli are supplieil from the stimulated areas and the remaining portions of the 

 body may be affected with spasms in the same succession in which the corresponding 

 motor regions in the cortex follow one another. The attack also occurs if complete 

 parts of tlie cranial cortical substance up to the motor zone have been removed, but 

 remains absent if only the motor region is extirpated, the other cortical section being 

 retained. After partial destruction of the motor cortical Jone one may succeed in 

 occasioning an attack but the muscles of the parts of the body whose corresponding 

 centers have been removed take no more part in the spasmodic contractions. 



The stimulation of the su])-cortical centers, after removing the motor region 

 of the cortex, causes general convulsions and irregular spasms (Ziehen, Binswanger 

 Prus). ' 



Up to the present time the nature of the causes of epilepsy 

 are not known exactly. It is assumed that certain parts of the 

 brain possess a greater degree of irritability than normally or 

 that their molecules themselves are in a state of very unstable 

 equilibrium, being affected easily and markedly by insignificant 

 irritation such as variations of blood pressure which produce 

 no effect whatever on the healthy brain. Of the nature of this 

 increased irritability no information is at hand, it has been only 

 observed that the ailment itself and the predisposition to it may 

 be transmitted to the progeny. In the individual with an heredi- 

 tary predisposition the disease can occur at a certain age with- 

 out traceable cause, but more frequently it happens that the 

 first attack is due to some external influence whilst later attacks 

 may arise without any external cause. Such occasional causes 

 appear to be pretty frequent in animals, for instance severe 

 psychic disturbances (fright, excitement, punishment), dazzling 

 rays of light (Lovy produced several attacks a day in a cow 

 from this cause) less frequently shocks to the body, blows, fall- 

 ing down, etc. 



In more recent times it is often assumed that epilepsy may be due 

 to an auto-intoxication. In the many experiments conducted on men 

 for the determination of definite poisons in the metabolism of the epileptic, 

 the experiments undertaken by Krainski may l)e mentioned especially.' 

 According to these investigations epilepsy is produced by the formation 

 of larger amounts of ammonium carbamate in consequence of an anomaly 

 in metabolism, which then irritates the cortex cerebri. 



Spasmodic attacks similar to epilepsy have also been produced by Hahn, Massen 

 Nencki and Pawlow in dogs with carbamate of calcium and sodium, but Putnam & 

 Pfaff could not confirm the findings of Krainski. In two cases Donath is inclined 

 to ascribe epileptic convulsions to cholin. 



Heredity is commonly looked upon as a cause of the pre 

 disposition. There are trustworthy records showing that the af 



