d renders so far persistent the delicate sporangium.
For more exact description the reader is again referred to the specific
delineations which follow.

The transition from phase to phase requires, as intimated, no great
length of time. _Tilmadoche polycephala_ completed the transition from
vegetative to fruiting phase in less than twelve hours.

The germination of the spores ensues closely upon their dispersal or
maturity and is unique in many respects.[7] The wall of the spore is
ruptured and the protoplasmic content escapes as a zoospore
indistinguishable so far from an amoeba, or from the zoospore of our
chytridiaceous fungi. This amoeboid zoospore is without cell-wall,
changes its outline, and moves slowly by creeping or flowing from point
to point. At this stage many of the spores assume each a flagellate
cilium, and so acquire power of more rapid locomotion. The zoospores,
whether ciliate or not, thus enjoy independent existence and are capable
of continuing such existence for some time, assimilating, growing, and
even reproducing themselves by simple fission, over and over again. This
takes place, of course, only in the presence of suitable nutrient media.

Nevertheless the spores of many species germinate quickly simply in
water, and a drop suspended in the form of the ordinary drop-culture on
a cover-glass affords ample opportunity. In the course of time, usually
not more than two or three days, the swarm spores cease their activity,
lose their cilia, and come to rest, exhibiting at most nothing more than
the slow amoeboid movement already referred to. In the course of two
or three days more, in favorable cases, the little spores begin to
assemble and flow together; at first into small aggregations, then
larger, until at length all have blended in one creeping protoplasmic
mass to form thus once again the plasmodium, or plasmodial phase with
which the round began. Small plasmodia may generally be thus obtained
artificially from drop-cultures. Such, however, in the experience of the
writer, are with difficulty kept alive. Hay infusions, infusions of
rotten wood, etc., may sometimes for a time give excellent results.

The spores of _Didymium crustaceum_ were sown upon a heap of leaves in
autumn. An abundant display of the same species followed in the next
June; but, of course, the intervening phases were not observed. The most
satisfactory studies are obtained by plasmodia carefully brought in
directly from t