382 THE CANADIAN NATURALIST. [June 



generated by the decomposition of vegetable and animal matter ; 

 Second, aeriform contagious, generated by the animal system in a 

 state of disease. First, infection may result from the humid 

 decomposition of vegetable and animal matter, contained in the 

 filth of cities, in marshes, and some soils furnishing these materials, 

 hence the designation marsh-miasma. Second, it may result 

 from the decomposition and natural exhalations and excretions of 

 the human body, under ill-conditioned circumstances ; to this has 

 been applied the term idio-miasma, expressive of the personal 

 or private character of its source. Marsh-miasma has also 

 received the name of malaria. Much has been written of malaria 

 but little of its true nature is understood, although it is supposed 

 to be the effluvia that generates fevers, cholera, and such like 

 diseases ; many physicians of eminence have written elaborately 

 on the subject — but after all, very little is really known of its 

 subtile influence. 



Here is a picture drawn by Dr. Macculoch: — " The fairest 

 portions of Italy are a prey to the invisible enemy, malaria — its 

 fragrant breezes are poison, the dews of the summer evenings are 

 death. The banks of its refreshing streams, its rich and flowery 

 meadows, the borders of its glassy lakes, the luxuriant plains of 

 its overflowing agriculture, the valleys, where its aromatic shrubs 

 regale the eye and perfume the air, these are the chosen seats of 

 this plague — the throne of malaria. Death here walks hand-in- 

 hand with the resources of life, sparing none. The labourer reaps 

 his harvest but to die, or he wanders amid the luxuriance of vege- 

 tation and wealth, the ghost of man, a sufferer from his cradle to 

 his impending grave ; aged even in childhood, and laying down in 

 misery that life which was but one disease. He is driven from 

 some of the richest portions of this fertile, yet unhappy country : 

 and the traveller contemplates, at a distance, deserts — but deserts 

 of vegetable wealth — which man dares not approach, or he dies." 

 Whatever is its composition, it may be enough for us to know 

 that its existence in the atmosphere is incompatible with health. 

 Now, Ozone is said to destroy this malaria ; no deleterious 

 substance is found in the atmosphere where Ozone is manifest, for 

 one of the peculiar properties of Ozone is, its disinfecting powers ; 

 putrid meat exposed to the action of ozonized air soon becomes 

 disinfected. Manure heaps and foul drains, where there is decom- 

 position going on, become quite innocuous : and it has been shown 

 that when putrid organic matter is subjected to the action of 



