504^ 



is the first occasion in modern times that the subject has 

 been brought forward, — in consequence of the great similarity 

 between yeast and the matter producing epidemic disease, I 

 would attach great importance to any substance as a disin- 

 fectant which would so completely destroy the action of the 

 former. The old plan of boiling tar and burning brown 

 paper in places charged with noxious exhalations, as a means 

 of disinfecting them, would not be without its use; for in 

 both cases creosote, &c., would be diffused through the 

 atmosphere in sufficient quantity to produce a marked effect ; 

 and I have no doubt, were such plans adopted and kept up 

 on an extensive scale in places exposed to epidemic disease, 

 they would very much tend to prevent the extension of the 

 malady. It will at once be evident that the action of these 

 substances differs widely from those commonly known by the 

 name of disinfectants; for while the latter are principally 

 calculated to destroy poisonous matters, when once generated, 

 by changing them into inert compounds, the former is destined 

 to strike at once at the cause of the evil, and, by a specific 

 action, to prevent their formation. 



Having now given a brief outline of the nature of malaria, 

 its mode of production and propagation, as well as the con- 

 ditions of atmosphere and soil most favourable to its develop- 

 ment, and the various natural and artificial agents calculated 

 to destroy it, we may deduce the following conclusions : — 



1. That the substance commonly called malaria is a nitro- 

 genous organic compound, which, when dissolved in water 

 or animal fluids, has similar properties to yeast, being in a 

 continued state of decomposition, which state of decomposition 

 it is capable of communicating to the fluids of the animal 

 body. 



2. That the character of the decomposition, and the variety 

 of disease it will communicate, differs materially at various 

 periods. 



