ative action is manifestly concurrent with its
multiplication. It finds its pabulum in the mass it ferments by its
vegetative processes. But it also produces a visible change in the
enveloping fluid, and noxious gases continuously are thrown off.

In the course of a week or more, dependent on the period of the year,
there is, not inevitably, but as a rule, a rapid accession of spiral
forms, such as _Spirillum volutans_, _S. undula_, and similar forms,
often accompanied by _Bacterium lineola_; and the whole interspersed
still with inconceivable multitudes of _B. termo_.

These invest the rotting tissues liked an elastic garment, but are
always in a state of movement. These, again, manifestly further the
destructive ferment, and bring about a softness and flaccidity in the
decomposing tissues, while they without doubt, at the same time, have,
by their vital activity and possible secretions, affected the
condition of the changing organic mass. There can be, so far as my
observations go, no certainty as to when, after this, another form of
organism will present itself; nor, when it does, which of a limited
series it will be. But, in a majority of observed cases, a loosening
of the living investment of bacterial forms takes place, and
simultaneously with this, the access of one or two forms of my
putrefactive monads. They were among the first we worked at; and have
been, by means of recent lenses, among the last revised. Mr. S. Kent
named them _Cercomonas typica_ and _Monas dallingeri_ respectively.
They are both simple oval forms, but the former has a flagellum at
both ends of the longer axis of the body, while the latter has a
single flagellum in front.

The principal difference is in their mode of multiplication by
fission. The former is in every way like a bacterium in its mode of
self-division. It divides, acquiring for each half a flagellum in
division, and then, in its highest vigor, in about four minutes, each
half divides again.

The second form does not divide into two, but into many, and thus
although the whole process is slower, develops with greater rapidity.
But both ultimately multiply--that is, commence new generations--by
the equivalent of a sexual process.

These would average about four times the size of _Bacterium termo_;
and when once they gain a place on and about the putrefying tissues,
their relatively powerful and incessant action, their enormous
multitude, and the manner in which they glide ov