a?icl of Ccntagiovs Dif cafes. 187 



be infinite gradations of the deleterious caufe, there may be 

 endlefs varieties in the morbid effect. 



** And to this principle of the human conftitution, I be- 

 lieve, may be referred all the febrile ailments from the moft 

 trifling intermittent to the more ferious remittent, and the 

 folemn form of continued fever. 



" Hence further may it be underftood how a fucceffion of 

 fits, long continued, may difpofe the conftitution to a repe- 

 tition of fits, even when the morbid caufe is away : for 

 though there may be a habit of infenfibility produced to the 

 vitiated airs, yet a habit may, in the mean while, be efta- 

 blifhed in the bodily motions of falling periodically into re- 

 gular trains of action, even when the original caufe is with- 

 held. Here then will be produced a habit of having pa- 

 roxyfms depending on the particular inward ftate of the 

 moving fibres, after the manner of temporary feafoningsj 

 while, at the fame time, there is a habit formed of refitting 

 the active caufes (vitiated air) altogether, or of obtaining a 

 permanent feafoning as to them. 



" The cold ftage of a paroxyfm is a ftate of direct debility, 

 induced by the vitiated air breathed operating to fubduc.1 heat 

 and oxygen from the body 3 and its termination is by the 

 ltimulus of the vitiated air being for that time worn out. 

 The hot ftage, which begins as foon as the temporary fea- 

 foning is induced, is a ftate of excitement brought on by 

 the heat and oxygen now operating upon the accumulated 

 excitability with additional force. — The fweating ftage is 

 formed after the fubfidence of the exceffivc action of the 

 body, and the confequent enlargement of the diameters of 

 the veflels, whereby fweat is formed by the combination of 

 hydrogen and oxygen, and the other fecrctions proceed 

 again, as ufual, in the fev'eral gland-;. 



" The length of interval between the paroxyfms depends 

 upon the ftrength of habit acquired. 



t* The frequency pf their occurrence will be proportioned 



tq 



