relations as ferment, that has specially occupied my fullest
attention; but it would be in a high degree interesting if we could
discover, or determine, what besides the vegetative or organic
processes of nutrition are being effected by one, or both, of these
organisms on the fast yielding mass. Still more would it be of
interest to discover what, if any, changes were wrought in the
pabulum, or fluid generally. For after some extended observations I
have found that it is only after one or other or both, of these
organisms have performed their part in the destructive ferment, that
subsequent and extremely interesting changes arise.

It is true that in some three or four instances of this saprophytic
destruction of organic tissues, I have observed that, after the strong
bacterial investment, there has arisen, not the two forms just named,
nor either of them, but one or other of the striking forms now called
_Tetramitus rostratus_ and _Polytoma uvella_; but this has been in
relatively few instances. The rule is that _Cercomonas typica_ or its
congener precedes other forms, that not only succeed them in promoting
and carrying to a still further point the putrescence of the
fermenting substance, but appear to be aided in the accomplishment of
this by mechanical means.

By this time the mass of tissue has ceased to cohere. The mass has
largely disintegrated, and there appears among the countless bacterial
and monad forms some one, and sometimes even three forms, that while
they at first swim and gyrate, and glide about the decomposing matter,
which is now much less closely invested by _Cercomonas typica_, or
those organisms that may have acted in its place, they also resort to
an entirely new mode of movement.