390 Address of Professor Hucley. 
singular changes in organic matters which are known as fer- 
mentation and putrefaction. The question of the generation 
of the infusory animalcules thus passed into a new phase. For 
what might not have happened to the organic matter of the 
infusions, or to the oxygen of the air, in Spallanzani’s experi- _ 
ments? What security was-there that the development of life 
which ought to have taken place had not been checked or pre- 
vented by these changes? 
The battle had to be fought again. It was needful to repeat 
the experiments under conditions which would make sure that 
neither the oxygen of the air, nor the composition of the organic 
matter, was altered in such a manner as to interfere with the - 
existence of life. 
chulz 
of view in 1836 and 1837. The passage of air through red-hot 
infusion. This “something” might be gaseous, fluid, or solid; 
that it consisted of germs remained only an hypothesis of greater 
or less probability. 
Contemporaneously with these investigations a remarkable 
iscovery was made by Cagniard de ur. He found that 
common yeast is composed of a vast accumulation of minute 
in some way or other, the causes both of fermentation and 
feat at atiniseag b> ae * i ae M stl | a y Physics, 
