XX. On the Nature and History of the Marsh Poison. By 

 William Ferguson, M. D. F. R. S. E. Inspector of Army- 

 Hospitals. 



(Read January 3. and 17. 1820.^ 



JlN this paper I propose submitting to the Society some ob- 

 servations on the nature and history of the Marsh Poison, 

 which, under the title of Marsh Miasmata^ or Malaria, has ever 

 been acknowledged as the undisputed source of Intermittent 

 Fevers, and is believed, with good reason, to be the exciting 

 cause of the whole tribe of Remittent Fevers ; — of Endemic 

 Fever, in fact, in every form, and in every part of the world. 



All authors who have treated of the nature of this poison, 

 (and they are most numerous), coincide in attributing its de- 

 leterious influence to the agency of vegetable or aqueous pu- 

 trefaction. So universal a coincidence has caused these opi- 

 nions to be received with the authority of an established 

 creed. It is my intention in this paper to shew, from a nar- 

 rative of facts, that they are unfounded, and that putrefaction, 

 under any sensible or discoverable form, is not essential to the 

 production of pestiferous miasmata. 



The marsh poison, happily so little known in this country, 

 and the colder regions of the earth, is notwithstanding by far 



M m 2 the 



