120 THE EVOLUTION OF LIFE 
birth of living matter. Let us see, however, what 
Pasteur’s attitude was in the face of such an 
eventuality. 
The experiments of Schwann have been commonly 
believed by many to have been altogether in favour 
of the germ-theorists. Those who read his memoir 
will find, however, that he did not fail to obtain 
living organisms in all his experimental fluids. 
When the fluids were such as were capable of under- 
going the alcoholic fermentation on exposure to the 
air, living organisms were, in spite of all precautions, 
sometimes found within his flasks. Many other 
observers have also found organisms in fluids from 
hermetically sealed flasks which had been strictly 
subjected to the conditions prescribed by Schwann ; 
and that, not unfrequently, when the change which 
the fluid had undergone was of a putrefactive rather 
than of a fermentative character. Among those 
who have obtained these positive results may be 
named Mantegazza, Pouchet, Joly, Musset, Wyman, 
Hughes Bennett, Child, and others. 
In spite of the fact that these investigators had 
obtained living things in vessels prepared after the 
manner of Schwann, when various infusions were 
employed, Pasteur was quite inclined to believe for a 
time, on the strength of his own experiments, that 
Schwann’s precautions, properly carried out, were 
adequate to prevent the appearance of organisms in 
the experimental fluids. His early investigations 
were made with sweetened yeast-water, concerning 

