ores, and the substratum of which is exhausted for our
fungus, short stationary pieces, filled with protoplasm, are very
often formed into cells through partitions in order to produce spores,
that is, grow to a new fruitful mycelium. These cells are called
gemmules, brooding cells, and resemble such vegetable buds and sprouts
of foliaceous plants which remain capable of development after the
organs of vegetation are dead, in order to grow, under suitable
circumstances, to new vegetating plants, as, for example, the bulbs of
onions, &c.

If we bring a vegetating mycelium of _Mucor mucedo_ into a medium
which contains the necessary nourishment for it, but excluded from the
free air, the formation of sporangia takes place very sparingly or not
at all, but that of gemmules is very abundant. Single interstitial
pieces of the ramuli, or even whole systems of branches, are quite
filled with a rich greasy protoplasm; the short pieces and ends are
bound by partitions which form particular, often tun-like or globular
cells; the longer ones are changed, through the formation of cross
partitions, into chains of similar cells; the latter often attain by
degrees strong, thick walls, and their greasy contents often pass into
innumerable drops of a very regular globular form and of equal size.
Similar appearances show themselves after the sowing of spores, which
are capable of germinating in the medium already described, from which
the air is excluded. Either short germinating utricles shoot forth,
which soon form themselves into rows of gemmules, or the spores swell
to large round bladders filled with protoplasm, and shoot forth on
various parts of their surface innumerable protuberances, which,
fixing themselves with a narrow basis, soon become round vesiculate
cells, and on which the same sprouts which caused their production are
repeated, formations which remind us of the fungus of fermentation
called globular yeast. Among all the known forms of gemmules we find a
variety which are intermediate, all of which show, when brought into a
normal condition of development, the same proportion, and the same
germination, as those we first described.

We have detailed rather at length the structure and development of one
of the most common of the Mucors, which will serve as an illustration
of the order. Other distinctions there may be which are of more
interest as defining the limits of genera, except such as may be
noticed when we come to