ON DUST AND DISEASE. 147 



' Ever,' he says, ' since the commencement of these 

 researches, I have been exposed to the most obstinate 

 and unjust contradictions ; but I have made it a duty to 

 leave no trace of these conflicts in this book.' And in 

 reference to parasitic diseases, generally, he uses the 

 following weighty words : 6 II estau pouvoir de 1'homme 

 de faire disparaitre de la surface du globe les maladies 

 parasitaires, si, comme c'est ma conviction, la doctrine 

 des generations spontanees est une chimere.' 



Pasteur dwells upon the ease with which an island 

 like Corsica might be absolutely isolated from the silk- 

 worm epidemic. And with regard to other epidemics, 

 Mr. Simon describes an extraordinary case of insular 

 exemption, for the ten years extending from 1851 to 

 1860. Of the 627 registration districts of England, 

 one only had an entire escape from diseases which, in 

 whole or in part, were prevalent in all the others : ' In 

 all the ten years it had not a single death by measles, 

 nor a single death by small-pox, nor a single death by 

 scarlet-fever. And why? Not because of its general 

 sanitary merits, for it had an average amount of other 

 evidence of unhealthiness. Doubtless, the reason of its 

 escape was that it was insular. It was the district of 

 the Scilly Isles ; to which it was most improbable that 

 any febrile contagion should come from without. And 

 its escape is an approximative proof that, at least for 

 those ten years, no contagium of measles, nor any 

 contagium of scarlet-fever, nor any contagium of small- 

 pox had arisen spontaneously within its limits.' It 

 may be added that there were only seven districts in 

 England in which no death from diphtheria occurred, 

 and that, of those seven districts, the district of the 

 Scilly Isles was one. 



A second parasitic disease of silkworms, called in 

 France laflaclierie^ co-existent with pebrine, but quite 



L 2 



