AND THE CAUSES OF FERMENTATION. 107 
to decide whether the exciting cause of this delayed 
turbidity is in part the living element whose vitality 
and rate of reproduction has been lowered by the 
heat or whether the effects are wholly attributable 
to the mere organic matter of the inoculating com- 
pound. 
So far, therefore, we have concomitant variations 
which are equally compatible with either hypothesis. 
But it will be found that each of the three succeeding 
arguments speaks more and more plainly against the 
possible influence of the living element, and in favour 
of the action of the organic matter of the inoculating 
compound, as an efficient exciting cause of the de- 
layed putrefactions occurring in the cases in question. 
3. As stated in my last communication,* when 
single drops of slightly turbid infusions of hay or 
turnip previously heated to 140° F. are mounted and 
securely cemented as microscopical specimens, no 
increase of turbidity takes place, although drops of 
similar infusions heated only to 122° F. do notably 
increase in turbidity (owing to the multiplication of 
Bacteria) when mounted in a similar manner. Under 
such restrictive conditions as these, in fact, a drop of 
an inoculated and previously heated organic infusion 
behaves in precisely the same manner as a drop of 
a similarly treated ammonic-tartrate solution. In 
.* Loc. cit. p. 228 [p. 87]. 
