ee LE 

312 THE EVOLUTION OF LIFE 
through industrial development the social conditions 
become bad, we have always and everywhere an 
increase of tuberculosis, and this depends more on 
the increase of predisposition than on the increase 
of exposition. . . . It is impossible to successfully 
fight against tuberculosis if we only fight against the 
bacilli. . . . It is therefore absolutely necessary to 
increase the resisting power by means of positive 
hygiene, or through training one’s self to health.” ? 
Bacteriologists, as a result of repeated processes of 
heating at brief intervals and often at high tempera- 
tures for the special purpose of bringing about 
complete sterilisation, not only kill all pre-existing 
micro-organisms, but, as I maintain, destroy also 
-any potential germinality of the media themselves. 
These media, after having been treated as above 
indicated, will nourish and favour the multiplication 
‘of living Bacteria with which they are inoculated, 
but they will never engender them. They behave, 
in fact, exactly like a boiled ammonium tartrate 
solution—this also does not engender, but will freely 
nourish Bacteria.2 Asa result of habitually dealing 
with media thus treated (though they know that, with 
the exception of the spores of Bacilli, all the microbes 
in their media may be destroyed by being boiled 
once only, for five minutes or less), bacteriologists 
have come to the conclusion that Bacteria never 
arise de novo. 
1 The Journal of State Medicine, Jany. 1904, p. 10. 
2 See pp. 57 and 58, where the difference between “nourishing ” and 
‘“‘ venerating” fluids has been more fully set forth. 
