148 FRAGMENTS OF SCIENCE. 



distinct from it, has also been investigated by Pasteur. 

 Enough, however, has been said to send the reader 

 interested in these questions to the original volumes for 

 further information. To one important practical point 

 M. Pasteur, in a letter to myself, directs attention : 



Permettez-moi de tsrminer ces quelques lignes 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, et des 

 principes que 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 

 convaincrez aisement qu'il est facile aujourd'hui, non- 

 seuleinent d'eloigner la maladie regnante, mais en outre de 

 donner aux recoltes de la soie une prosperite qu'elles n'ont 

 jamais eue. 



Origin and Propagation 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 attributed the cause of the 

 disease.' Those acquainted with our 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 ill-smelling 

 drains. According to them, the contagia of epidemic 

 disease are formed de novo in a putrescent atmosphere. 

 On the other side we have writers, clear, vigorous, with 

 well-defined ideas and methods of research, contending 



