298 THE EVOLUTION OF LIFE 
view when he said!: “If I can trace contagion in a 
very large number of the so-called specific diseases, 
I consider it more reasonable to assume contagion 
in the minority than look about for another cause.” 
And he went on to say that, as many of these 
diseases are associated with the growth and multi- 
plication ‘‘of living specific organisms” a belief in 
the de novo origin of these contagious diseases would 
“imply also a belief in spontaneous generation.” 
This latter view, although it is so prevalent, is 
surprisingly fallacious. 
There can be no doubt, of course, that the estab- 
lishment of the reality of “spontaneous generation ” 
must certainly have a very potent influence in gradu- 
ally breaking down the notion that communicable 
diseases, simply because they are associated with 
‘“specific’’ micro-organisms, cannot arise de novo. 
If such organisms can arise de novo, of course the 
diseases could arise de zovo ; and, further, the fact of 
such an origin for microbes would easily carry with 
it the certainty that they would be extremely mutable 
under the influence of changing conditions, though 
otherwise capable of ‘‘ breeding true.” 
Still, independently of a belief in the spontaneous 
generation of microbes, there is another and simpler 
way by which the “specific” micro-organisms may 
enter upon the scene. This mode seems to have 
been lost sight of by the distinguished authority to 
whom I have last referred, while it was mentioned 
only to be repudiated by the second reviewer above 
quoted. Yet bacteriologists themselves have gradu- 
1 The Lancet, Oct. 31, 1903. 

