88 PHYSIOLOGY. 



is, accordingly, not a more frequent occasional cause of epilepsy 

 than a little increase of fulness in the vessels of the brain. Gau- 

 bius applies this to the whole system ; but the effect of which I 

 speak, happens especially when there appears some increased 

 impetus in the vessels of the brain ; the fulness, as general over 

 the system, is rather to be considered as a cause of mobility, 

 which, however, has a share here. I need not add here that 

 the effect of the determination to the brain in producing epi- 

 lepsy appears from this, that convulsions often happen where 

 we have proof of an increased impetus, and where there is a de- 

 gree of inflammation, as in phrenitis. 3. Indirect stimulants : 

 ' Immodica evacuatio.' The chief proof of this is taken from 

 haemorrhagy. Dr. Hales was much occupied in experiments 

 which led him to bleed animals to death ; and he constantly 

 found that no animal died thus without being affected with epi- 

 lepsy, of which our butchers have evidence every day. Another 

 proof that epilepsy may be brought on by causes of debility, is, 

 that nothing is more common than syncope, attended with con- 

 vulsion, so that both these symptoms must be imputed to one 

 and the same cause. But further, many sedatives most power- 

 fully narcotic, and therefore most capable of inducing a state of 

 collapse, particularly opium, do not kill without producing con, 

 vulsion ; and it is very probable that as poisons so universally 

 have the effect of producing epilepsy and convulsive motions, 

 more of them are of the sedative kind than has been imagined, 

 though, at the same time, some of them may operate by their 

 stimulant power and the inflammation they produce. With re- 

 gard to the effects of odours, I do not positively determine 

 how far they are sedative. I doubt if their effects in produc- 

 ing convulsions are owing to their sedative power ; and I am of 

 opinion that they do so only in so far as they are disagreeable ; 

 and that if musk, for instance, occasions convulsions, it is because 

 it proves as disagreeable as the most fetid substance, so that it 

 is the degree of the disagreeable sensation that has this effect. To 

 this head I must refer the emotion or passion of fear, which is so 

 frequently the cause of epilepsy, and which is to be explained, not 

 only by its direct sedative effects, but from its disturbing, in 

 consequence of the surprise, the measure of the animal power." 

 CXIII. If the contractions of muscles are exerted with un- 



