EPILEPSY AND APOPLEXY. 261 



afforded of that sudden suspension of the cerebral 

 functions which forms the most striking phenomenon 

 in epileptic and apoplectic seizures. The brain, as 

 we have seen, is contained in a rigid bony case, 

 which it completely fills : it is, during life, of a 

 semi-fluid consistence, and therefore capable of 

 transmitting pressure equally in all directions. In 

 its substance, and on its surface, are innumerable 

 minute vessels, the coats of which are extremely 

 thin ; and through those vessels, in the healthy state 

 of the organ, streams of blood constantly flow with 

 considerable velocity ; at its base are situated the 

 large cerebral arteries, and along its upper and pos- 

 terior portion are placed the strong and capacious 

 sinuses communicating with the jugular veins. We 

 observe that other internal organs, such as the liver 

 and kidney, are liable to rapid enlargement as the 

 result of an accumulation of blood in their vessels, 

 origanatins; either in an increased influx through the 



O O O 



arteries, or a diminished efflux through the veins. 

 And it is certain, from the observation of symptoms 

 frequently present, as well as from the study of the 

 anatomical, physiological, and pathological pecu- 

 liarities and relations of the brain, that the arterial 

 and venous tubes subservient to the motion of the 

 blood through its minute vessels, are also subject to 

 similar irregularities in their rate of discharge. What 

 effect, then, will a suddenly-induced disproportion 

 between the rates of influx and efflux of blood to 

 and from the interior of the cranium, exercise upon 

 the motion of that fluid in the minute vessels of the 



brain ? 



s 3 



