ructive species for study, which even very lately
have occupied the attention of continental mycologists. Most of these
phenomena are associated more or less with reproduction, and as such
will have to be adverted to again, but there are points in the
structure which can best be alluded to here. Again taking Professor de
Bary's researches as our guide,[s] we will illustrate this by the
common _Mucor mucedo_: If we bring quite fresh horse-dung into a damp
confined atmosphere, for example, under a bell-glass, there appears on
its surface, after a few days, an immense white mildew. Upright strong
filaments of the breadth of a hair raise themselves over the surface,
each of them soon shows at its point a round little head, which
gradually becomes black, and a closer examination shows us that in all
principal points it perfectly agrees with the sporangia of other
species. Each of these white filaments is a sporangia-bearer. They
spring from a mycelium which is spread in the dung, and appear singly
upon it. Certain peculiarities in the form of the sporangium, and the
little long cylindrical spores, which, when examined separately, are
quite flat and colourless, are characteristic of the species. If the
latter be sown in a suitable medium, for example, in a solution of
sugar, they swell, and shoot forth germinating utricles, which quickly
grow to mycelia, which bear sporangia. This is easily produced on the
most various organic bodies, and _Mucor mucedo_ is therefore found
spontaneously on every substratum which is capable of nourishing
mildew, but on the above-named the most perfect and exuberant
specimens are generally to be found. The sporangia-bearers are at
first always branchless and without partitions. After the sporangium
is ripe, cross partitions in irregular order and number often appear
in the inner space, and on the upper surface branches of different
number and size, each of which forms a sporangium at its point. The
sporangia which are formed later are often very similar, but sometimes
very different, to those which first appeared, because their partition
is very thick and does not fall to pieces when it is ripe, but
irregularly breaks off, or remains entire, enclosing the spores, and
at last falls to the ground, when the fungus withers. The cross
partition which separates the sporangia from its bearers is in those
which are first formed (which are always relatively thicker sporangia)
very strongly convex, while t