514 PRACTICE OF PHYSIC. 



continue in the form of a remittent or continued, and that mere- 

 ly from the duration of the paroxysms ; and this is further con- 

 firmed from what we observed before with respect to the change 

 of the form of fevers ; for it is by the prolongation of paroxysms 

 that quartans and tertians change into quotidians, and these 

 again into remittent and continued fevers. 



" We conclude accordingly, that the form of fevers depends 

 upon the duration of the paroxysms themselves ; hence, in or- 

 der to account for the different forms of fevers, we must look 

 out for the cause of the duration of the paroxysms, or inquire 

 into the circumstances that determine their nature. This is a 

 difficult problem, but I hope we shall be able to make some 

 progress here with probability and clearness."" 



LIX. Agreeably to what is laid down in XLVI., and to the 

 opinion of most part of physicians, I suppose, that in every 

 fever there is a power applied to the body, which has a tendency 

 to hurt and destroy it, and produces in it certain motions which 

 deviate from the natural state ; and, at the same time, in every 

 fever which has its full course, I suppose, that, in consequence 

 of the constitution of the animal economy, there are certain 

 motions excited which have a tendency to obviate the effects of 

 the noxious power, or to correct and remove them. Bo'th these 

 kinds of motion are considered as constituting the disease. 



But the former is perhaps strictly the morbid state, while the 

 latter is to be considered as the operation of the vis medicatrix 

 natures, of salutary tendency, and which I shall hereafter call 

 the REACTION of the system. 



LX. Upon the supposition that these two states take place 

 in every paroxysm of fever, it will appear to be chiefly in the 

 time of the hot stage that the reaction operates in removing the 

 morbid state ; and, therefore, as this operation succeeds more 

 or less quickly, the hot stage of paroxysms will be shorter or 

 longer. But as the length of paroxysm depends chiefly upon 

 the duration of the hot stage, so the longer duration of this and 

 of paroxysms, must be owing either to the obstinacy of resist- 

 ance in the morbid state, or to the weakness of the salutary re- 

 action ; and it is probable, that sometimes the one, and some- 

 times the other of these circumstances takes place. 



LXI. It seems to be only by the state of the spasm, that we 



