180 MICROBES, FERMENTS, AND MOULDS. 



of the subjects of intermittent fever. By exposure 

 during the night of little glass plates in marshy 

 meadows, Salisbury was able to collect similar spores, 

 which settled on the lower surface of the glass, and 

 were found floating in the drops of condensed dew.* 

 On passing through these marshes in the evening, 

 there was a peculiar sense of dryness in the throat, 

 and expectoration revealed the presence of spores of 

 Palmella. Finally, earth taken from these marshes 

 was found to be full of the same organisms. 



When the marsh begins to dry up, the spores are 

 produced in abundance, and intermittent fevers occur. 

 Salisbury writes that " in 18H2, the weather was very 

 wet until about the 1st of July ; but that during 

 July, August, and September, there was hardly a drop 

 of rain. The springs and water-courses were nearly 

 dried up, the marshes and wet grounds also became 

 dry, vegetation was almost completely arrested, and 

 the whole country presented an arid appearance. 

 Shortly after the drought began, intermittent fever 

 made its appearance in all the unhealthy districts, and 

 spread so rapidly during the months of July and 

 August, that it attacked almost every family living 

 on marshy ground. 



" A low, peaty meadow extends along the canal 



* We must repeat what has been said before^, that the presence 

 of these spores in the air is quite independent of that of the vapour 

 which constitutes dew ; in other words, the vapour does not transport 

 these spores, which must, on the contrary, be perfectly dry before they 

 can float in the air and settle on any damp object. 



