250 ADDITIONAL NOTES ON CONTAGION. 



paramount in the minds of those whose object, in all discussions, is truth. Subsequent 

 inquiry and reflection have convinced me that I stood not on solid ground, when i staled, 

 that among the causes of pestilence is the product of animal substances of every descrip- 

 tion, deprived of life, and in a state of putrefaction: and I cordially agree with the critic 

 on my letter to Haygarth, when he says, "We are more inclined lo think that there is a 

 specific contagion distinct from mere putrefaction, and which, perhaps, is not cognizable 

 by any of our senses." — Crit. Rev. July, lilOd. 



It may be asked, as all contagious diseases proceed from certain specific or peculiar 

 causes, what are those causes, and how arises that diversity of character assumed by 

 contagions? To this question we must be silent; for no pathologist, however experi- 

 enced, and however deep his research into nature may be, can give a satisfactory answer. 

 We know that there is such a diversity, and, in general, we have some knowledge of the 

 treatment they severally require. Perhaps this is as much as we ought to know. It is a 

 subject which must for ever elude human research. Neither anatomy nor chemistry give 

 any aid here. Exuberant fancy may, indeed, wanton in theory, and may conceive every 

 different form of contagion as proceeding from a different combination of the same che- 

 mical principles acting differently on the organs of our frame, or on the fluids which 

 they secrete. But strip these notions of their fancy-dress; let them stand naked be- 

 fore us, and they become mere phantasms. Par levibus ventis, volucrique simillimaso..ino. 



Believe me to be, 



Dear sir, very faithfully your's, 

 Dr. Hosack. C. CHISHOLM. 



NOTE C. {See page 205.; 



The American publishers of the New-York edition of Neale's translation of the work of 

 \ssalini on the plague of Egypt, in their introductory observations, have, among others, 

 !he following singular remark : 



" The existence of such contagion [of the plague] has never been proved by the evi- 

 dence of one of the senses. The contagion is a mere conceit of the mind ; and all rea- 

 soning upon such a visionary and fancied agent can be but hypothesis, and have no better 

 claim to our assent than the fluid of magnetism, and the ether of gravitation; an assump- 

 tion not near so worthy of our assent, as if it had been said, that the invisible angel of de- 



