152 PHYSIOLOGY OF THE BACTERIA. 
and dead nature, if the air has always the same 
composition, if the waters are always equally fer- 
tilizing, it is thanks to the infinitely minute agents 
of fermentation and putrefaction”’ (Duclaux). 
But the rdle of bacteria is not limited to this. 
«They invade also the living organism,” says Du- 
claux, “ and bring in their attack this double char- 
acter of infinite smallness in the apparent means 
and powerful destructive energy in the results. 
From this source come diseases of which medicine, 
not long since, did not know the cause, and which 
she only commences to refer to their veritable 
origin. For those who are aw cowrant with the 
first steps which she has made in this new line of 
research, with the fecundity of her first glimpses, 
with the richness of her first results, it is not 
doubtful that she will soon succeed in demonstrat- 
ing the parasitic nature of the gravest epidemic 
maladies.” 
§ 3.— Rote or THE BactTerIA IN ContTAGIOUS 
MALADIES AND VIRULENT AFFECTIONS. 
We shall first pass in review the different af- 
fections in which the presence of bacteria has 
been indicated, whether they have been given as 
the cause of the malady or considered as simple 
epiphenomena. 
Septicemia. — According to the hypothesis of 
Borsieri and of Gaspard upon the nature of septic 
blood, Sédillot demonstrated by some very con- 
clusive experiments that the imfective power is 
due to formed elements (des éléments figurés). 
