and
extremely beautiful fungus-like organisms common in all the moist and
wooded regions of the earth. Deriving sustenance, as they for the most
part do, in connection with the decomposition of organic matter, they
are usually to be found upon or near decaying logs, sticks, leaves, and
other masses of vegetable detritus, wherever the quantity of such
material is sufficient to insure continuous moisture. In fruit, however,
as will appear hereafter, slime-moulds may occur on objects of any and
every sort. Their minuteness retires them from ordinary ken; but such is
the extreme beauty of their microscopic structure, such the exceeding
interest of their life-history, that for many years enthusiastic
students have found the group one of peculiar fascination, in some
respects, at least, the most interesting and remarkable that falls
beneath our lens.

The slime-mould presents in the course of its life-history two very
distinct phases: the _vegetative_, or growing, assimilating phase, and
the _reproductive_. The former is in many cases inconspicuous and
therefore unobserved; the latter generally receives more or less
attention at the hands of the collector of fungi. The vegetative phase
differs from the corresponding phase of all other plants in that it
exhibits extreme simplicity of structure, if structure that may be
called which consists of a simple mass of protoplasm destitute of
cell-walls, protean in form and amoeboid in its movements. This phase
of the slime-mould is described as plasmodial and it is proper to
designate the vegetative phase in any species, as the _plasmodium_ of
the species. It was formerly taught that the plasmodium is unicellular,
but more recent investigation has shown that the plasmodial protoplasm
is not only multinuclear but karyokinetic; its cells divide and
redivide, as do the _reproductive_ cells of plants and animals
generally. Nevertheless, in its plasmodial phase, the slime-mould is
hardly to be distinguished from any other protoplasmic mass, may be
compared to a giant amoeba, and justifies in so far the views of those
systematists who would remove the slime-moulds from the domain of the
botanist altogether, and call them animals. The plasmodium is often
quite large. It may frequently be found covering with manifold
ramifications and net-like sheets the surface of some convenient
substratum for the space of several square feet.

The substance of the plasmodium has about the consistency of