416 PRACTICE OF PHYSIC. 



ing, wherever we can do it clearly, as the doing so may often 

 be of use in directing our practice. 



MCCLXXXVII. First, then, of the occasional causes act- 

 ing by excitement : they are either such as act immediately and 

 directly upon the brain itself; or those which are first applied 

 to the other parts of the body, and are from thence communi- 

 cated to the brain. 



MCCLXXXVIII. The causes of excitement immediately 

 and directly applied to the brain, may be referred to the four 

 heads of, 



1. Mechanical Stimulants ; 



2. Chemical Stimulants ; 



3. Mental Stimulants ; and, 



4. The peculiar Stimulus of Over-distention. 

 MCCLXXXIX. The mechanical stimulants may be, 



wounding instruments penetrating the cranium, and entering 

 the substance of the brain ; or splinters of a fractured cranium 

 operating in the same manner ; or sharp-pointed ossifications, 

 either arising from the internal surface of the cranium, or form- 

 ed in the membranes of the brain. 



MCCXC. The chemical stimulants (MCCLXXXVIII.) 

 may be fluids from various causes lodged in certain parts of the 

 brain, and become acrid by stagnation, or otherwise. " It has 

 been frequent, upon dissections of epileptics, to find abscesses, 

 or effusions, containing fluids manifestly vitiated, and justly sus- 

 pected of peculiar acrimony. These have accordingly, and per- 

 haps properly, been considered as the cause of the epilepsy 

 which attended ; but we must not arrive at this conclusion too 

 rashly. It is to me probable, that these abscesses and effusions 

 often depend upon the previous foundations of tumours, or pre- 

 vious states of inflammation, or increased impetus ; and we find, 

 that this, independently of any peculiarity in the nature of the 

 matter, can produce epilepsy."" 



MCCXCI. The mental irritations acting by excitement, are 

 all violent emotions of the active kind, such as joy and anger. 

 The first of these is manifestly an exciting power acting strongly 

 and immediately on the energy of the brain. " And indeed it 

 acts manifestly upon the nervous system almost alone." The 



