290 FRAGMENTS OF SCIENCE. 



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 silk-worms, called in France 

 laflacherie, coexistent with pebrine but quite distinct from 

 it, has also been investigated. Enough, however, has been 

 said to send such of you as are interested in these questions 

 to the original volumes for further information. To one 

 important practical point M. Pasteur, in a letter written to 

 me, directs attention : 



" Permcttez-moi de terminer ces quelques ligues que je dois dieter, 

 vaincu que je suis par la maladie, en vous faisant observer que vous 

 rendriez service aux Colonies de la Grande-Bretagne en repandant la 

 connaissance de ce livre, etdes principesque j'etablis touchant la maladie 

 des vers a soie, Beaucoup de ces colonies pourraient cultiver le murier 

 avec succes, et en jetant les yeux sur mon ouvrage vous vous convaiucrcz 

 aisement qu'il est facile aujourd'hui, non-seulement d'eloigner la maladie 

 regnante, mais en outre de donner aux recoltes de la soie une prospcrite 

 qu'elles n'ont jamais cue." 



Origin and Prolongation of Contagious Matter. 



Prior to Pasteur, the most diverse and contradictory 

 opinions were entertained as to the contagious character of 

 pebrine ; some stoutly affirmed it, others as stoutly denied 

 it. But on one point all were agreed. " They believed in 

 the existence of a deleterious medium, rendered epidemic 

 by some occult and mysterious influence, to which was at- 

 tributed the cause of the disease." Those acquainted with 

 medical literature will not fail to observe an instructive 

 analogy here. We have on the one side accomplished 

 writers ascribing epidemic diseases to "deleterious media," 

 which arise spontaneously in crowded hospitals and over 



