308 On Malaria. 
been known to occur in such situations.* Another proof, and it is 
deemed sufficient, is the fact, that when the bodies of the Cimetiére des 
Innocens, which were in every stage from incipient putrefaction to com- 
plete decomposition, were disinterred and reinhumed, not a case of 
fever appeared during the whole operation, \ hich occupied two years. 
I cannot see any reason to deny that some deleterious exhalation 
may originate in the materials which form the mud of marshes, and 
which every where support vegetation, except, that it is unascertaina- 
ble by chemical analysis; and further, that the pestilential agent is 
subdued by frost. There is no evidence that mineral or earthy sub- 
stances contribute in any degree to malaria, except clay, which, by 
preventing the subsidence of water, remotely causes the maceration 
of plants, and a consequent disengagement of malarious effluvia ; 
but this being purely a mechanical ts the quality of the effluvia 
cannot in any degree be referred to the c 
‘It must be inferred that some foreign mies are svolend by the 
moisture in these pestiferous exhalations, because pure water pro- 
duces no deleterious effects.| The spray of cataracts is not un- 
healthy, and sea fogs,t the mists which occur in thaws, or on high 
mountains, or in high northern latitudes, are never followed with un- 
favorable consequences. But whatever it is, whether a combination 
of agents, or a single agent, it appears to have a vegetable origin, and 
by its chemical union with water, or its elements, a new entity is pro- 
duced, which is a poison, and which, being exhaled, constitutes the 
marsh miasmata, or malaria. 
e naturalists have conjectured that electricity has an agency in 
this specific poison ; “ but nature accomplishes her wonders, not by 
employing a multitude of agents, but by merely varying the combi- 
nation of a few simple means,” and from what we know of electrical 
phenomena, it might be expected to exercise a salutary influence, by 
agitating the atmosphere, and dispersing the mephitic vapors. 
That heat is essential to its extrication, is proved by the increased 
virulence of the miasma after the hot season, and the greater vio- 
* Many examples might be adduced, such as various processes in making leather, 
pe je glue, catgut, &c. and above all, in Paris, the occupation of the 
, a set of men who esi dead horses to useful purposes, but among whom 
no wedeenic fever has been know 
mes think Dr. Fordyce sieht er santicaahy. that it is the dampness alone of 
which causes fever. 
Pe feels os on Rhode Island and Newfoundland. The’ former sa is dis- 
‘or , and is resorted to by strangers for a summer residen 
