Ylll PREFACE. 



at least understand what are the points which will eventually 

 lead to the elucidation of the peculiarities in this respect ; 

 and we can recognise most clearly that it is not correct to 

 regard in a one-sided manner the soil or the water as the only 

 important factor. In every case we may hope that a continued 

 experimental investigation carried on with a definite aim will 

 lead us most quickly to an increase of our knowledge, and to a 

 rational method of prophylaxis against the epidemic diseases. 



Many other duties have prevented me from finishing the 

 publication of this hook as quickly as I could have wished. I 

 have not heen able to utilise completely the literature of 1885, 

 and only the most important of the works which have appeared 

 in the present year have been added while the book was passing 

 through the press. The yearly report of micro-organisms lately 

 published by Baumgarten, and written with as much care as 

 knowledge, relieves me, however, of the necessity of giving in an 

 appendix a notice of the more recent works. 



C. FLUGGE. 



GdlTINGEX, 



August 24th, 1886. 



