AND THE CAUSES OF FERMENTATION. 123 
to as characterizing group E.* But just as amongst 
the self-fermentable fluids we find there are some 
which only engender Zorule or other allied fungus- 
germs, so now we find that some previously boiled 
fluids, even when fully exposed to the air, swarm only 
with Torule. Those exciting agents derived from the 
atmosphere which, with one set of fluids, initiate 
changes leading to the evolution of Bacteria, with 
another set lead only to the evolution of Zorule. 
And whilst telling us that the Bacteria which appear 
in previously barren fluids after exposure to air are 
not due to their contamination with germs of Bacteria, 
some observers would have us conclude that the Torule 
which appear in other previously barren fluids after a 
similar exposure are the products of preexisting aérial 
germs of such organisms. This conclusion, however, 
cannot readily be accepted in the face of the evidence 
derived from the closed-flask experiments with self- 
fermentable fluids of the lowest degree.f Such experi- 
ments, in fact, render the hypothesis as to the wide- 
spread distribution of aérial germs of Torul@ wholly 
unnecessary, by showing that certain fluids, by reason 
* In illustration of this statement see ‘‘The Beginnings of Life,” 
Appendix C, Exps, viii., ix., xiv., xv., xviii., XX., XXVi., XXX., XXxlii, 
and xxxvi. 
+ The only evidence in favour of such a conclusion is not one jot 
more conclusive than that which was formerly adduced in favour of the 
universal prevalence of Bacterta-germs in the air. 
