FEVERS. 553 



epidemics as the occasional cause of the fever in particular per- 

 sons, as in those cases the persons most under the impression 

 of fear are most easily affected. 



" The presence of food in the stomach has not only the power 

 of exciting that particular organ, but from the connexion of the 

 stomach with the system, it may affect the whole body ; and 

 though we should not be able to explain the manner of its oper- 

 ation, it is a fact that affections of the stomach are accompanied 

 with a frequency of pulse and horror, which form a kind of fever; 

 and this is more or less according to the quantity and quality 

 of the food introduced ; so that certain aliments alone may be 

 the cause of fever, or, as having a tendency this way themselves, 

 they may act in concurrence with other causes which give them 

 more power and activity. Thus, we observe, that indigestion 

 frequently excites and renews intermittent fevers. Here, how- 

 ever, we cannot answer several questions which might be started ; 

 as why vegetables of difficult digestion, such as cucumbers, me- 

 lons, &c. or why milk and fish together act this way ? But the 

 fact is enough to our purpose, and our not being able to give 

 the theory of the operation does not affect it."" 



XCVIII. Having now mentioned the chief of the remote 

 causes of fevers, it may be further observed, that these will arise 

 more or less readily, according as miasmata and contagions are 

 more or less favoured by the concurrence of cold and other se- 

 dative powers. 



u Contagion, like other powers acting upon our system, is 

 subject to the power of habit, and by repetition becomes inef- 

 fectual ; and it is in this way that men who have been some 

 time in jail frequently resist it, while others upon their coming 

 in are readily affected. In this way also, the West Indians 

 escape the yellow fever with which the Europeans on going 

 among them are frequently attacked. This circumstance has 

 given occasion to doubt if it is a contagious disease ; but the 

 fact is, it only does not attack the persons who are habituated 

 to it, and we also find that it is contagious when it is carried to 

 other places. I am willing to believe that physicians escape 

 contagion because they are at first exposed to it in small quan- 

 tity, and by habit become capable of resisting it ; and it is to 



VOL. i. 2 R 



