AND ANIMAL LIFE. 351 



epidemic diseases, if it have not, for a short time 

 previous to exposure, been deranged by excess 

 of some kind. -The reason of this will pro- 

 bably be understood from the following con- 

 siderations. The blood is the only general sti- 

 mulus of the body, and the different organs 

 will be excited or depressed according to the 

 properties of this fluid. Whether the agent 

 which produces fever be effluvia from the body, 

 or an impure condition of the atmosphere, it is 

 always to be regarded as a sedative, and its in- 

 fluence is to diminish the powers of life. When 

 an individual possesses superior physical endow- 

 ments of the system, he is less prone to conta- 

 gious diseases, because the natural stimulus of the 

 blood is sufficient to counteract the evil pro- 

 perties of that to which it is exposed. It is on 

 this account that persons who are kept in a con- 

 stant state of excitation from spiritous liquors, 

 can frequently mingle with impunity among 

 those infected with contagious disease ; and it is 

 also from the same cause that fever has in many 

 instances been cut short. 



CCCCXX. When I remark that the strong 

 and vigorous are often exempt from contagion, 

 it is necessary to limit the observation, or to 

 state those circumstances which seem on the one 

 hand to support, and on the other to invalidate 

 the opinion. When individuals from the country, 

 possessed of sound constitutional qualifications, 

 are brought within the influence of contagion, 



