94 PHYSIOLOGY. 



some stimulus on the brain and nerves.' When the increase of 

 vigour is equal over the whole system, and therefore suited to 

 the general tenor of the economy, it is indeed not a disease, but 

 the most perfect state of health. But I think Dr. Whytt has 

 forgot to observe that if this state is in any respect partial, it 

 certainly is a disease. It is not easy to establish an instance of 

 this partial excess ; but I think we have one in the phlogis- 

 tic diathesis, which, I conclude, consists in an increased tone 

 of the arterial system, and is certainly partial in relation to the 

 general system, for commonly there is, at the same time, a 

 diminished tone of the other muscles, particularly those of 

 voluntary motion, and often those of the alimentary canal. 

 But, even as affecting the whole system, the increase of vig- 

 our forms a predisposition to disease, as exposing persons to 

 be acted upon more readily by occasional causes, and dis- 

 posing them to inflammatory diseases, to the partial excess of 

 vigour in the phlogistic diathesis, and, as combined with more 

 or less mobility, to other diseases, as melancholia, hypo- 

 chrondriasis, and mania. Dr Whytt (L. c. p. 528,) alleges 

 that the increased power of the nerves never produces a disease 

 without a concurrent occasional cause. c Thus,' says he, c a 

 tetanus, or unusual spasmodic contraction of any muscle, is not 

 owing to an increase of that power in its nerves which is neces- 

 sary for muscular motion, but to an extraordinary exertion of it 

 in consequence of some uncommon irritation or affection of the 

 brain and nerves.' This is very true, but if we take the history 

 of the cases of tetanus occurring in the West Indies, we 

 find that men are more liable to the disease than women ; and 

 men, in proportion as they are more robust. It appears, there- 

 fore, that this increased vigour is a predisposition, and concurs 

 in aggravating the disease. 



" But if debility is concerned in so many instances in pro- 

 ducing disease, we cannot consider it properly without at the 

 same time considering its opposite, the increased vigour of the 

 system. Here the term of strength, however, is applied to dis- 

 ease, which may appear a little uncouth, and may be exposed 

 to cavil, as Dr. Whytt imagined ; on this account I have em- 

 ployed the term of < increased tone,' though I am not certain that 

 even this is altogether free from objection. 



