Pathogenic Microbes of the Static Condition. 41 



undergoing any evolution in the surrounding media. 

 Of these, two varieties are distinguished ; 1st. those 

 which, little resistant, perish immediately on leaving 

 the organism, and the transmission of which must be 

 made directly by contact of a diseased subject with a 

 healthy subject : syphilis, gonorrhoea, rabies ; 2d. those 

 which, more resistant, are preserved for a certain timje 

 outside of the economy, without however multiplying, 

 and may arrive upon healthy subjects by means of vari- 

 ous vehicles, contact with a diseased subject not being 

 absolutely necessary : measles, variola, scarlatina, diph- 

 theria, glanders, tuberculosis. In this case the source 

 of the contagious disease resides principally but not 

 exclusively in the diseased organism. If the germ is 

 met with elsewhere it will be upon objects which have 

 been in direct relation with the diseased or its cada- 

 ver ; these objects can, moreover, communicate the 

 latent germs of which they are bearers to the ordinary 

 media : soil, water, or air, in which these germs pre- 

 serve their contagiousness for a period of time more 

 or less extended. 



Whatever variations there may be in the mode of 

 contagion, the contagious obligatory parasite arrives 

 upon the healthy organism in the same condition in 

 which it left the diseased subject where it had its 

 origin. 



Contagious facultative parasites. — These live and 

 multiply not only within the organism of animals, but 

 also outside of the latter, upon dead organic matters, 

 in waters, etc.; germs of pysemia, septicaemias, gan- 

 grene, erysipelas, typhoid fever, asiatic cholera. 



The virulence of some of these germs seems even 

 to be diminished by their passage through the organ- 



