THEORY OF FEVER. 1073 



no longer in a condition to nourish the brain, 

 nerves, muscles, and other tissues, when a very 

 slight exposure to fatigue, cold, or some other 

 exciting cause, brings on a chill, stagnation of 

 blood in the lungs, torpor of the skin, kidneys, 

 bowels, and a retention of nearly all the effete 

 matter of the body in the blood, which is thus 

 still further vitiated. The manner in which the 

 blood is depurated by the various excretions, and 

 vitiated by their retention, may be strikingly 

 illustrated by the sanatory police of London. For 

 example, the sewers of that immense city perform 

 the same office in carrying off its excrementitious 

 matter as do the skin, kidneys, and bowels, which 

 are the natural sewers of the living body. If the 

 supply of fresh water were cut off, and the ex- 

 cretory ducts of London were obstructed for a 

 few months, or even weeks, it would be very soon 

 visited by the plague or some fatal epidemic, as 

 in former times, when suffered to remain in a 

 filthy state. 



I have already shewn, that the hot com- 

 mences sooner after the first symptom of the cold 

 stage, and continues for a longer time, in propor- 

 tion to the previous vitiation of the blood : that 

 when the latter is slight, the cold stage remains 

 from one to two hours or longer, and the paroxysm 

 about five hours, after which there is an inter- 

 mission of all the symptoms, excepting slight 

 debility, until the fourth day, as in quartans : 



