come into close contact
through a considerable length, and clasp each other by alternate
protuberances and depressions. Some of the protuberances are prolonged
into slender tubes. At the same time the free extremities of the
threads dilate, and arch over one towards the other until their tops
touch like a vice, each limb of which rapidly increases in size. Each
of these arcuate, clavate cells has now a portion of its extremity
isolated by a partition, by means of which a new hemispherical cell is
formed at the end of each thread at its point of junction with the
opposed thread. These cells become afterwards cylindrical by pressure,
the protoplasm is aggregated into a mass, the double membrane at the
point of first contact is absorbed, and the two confluent masses of
protoplasm form a zygospore invested with a tubercular coat and
enveloped by the primary wall of the two conjugating cells. During
this formation of the zygospore, the two arched cells whence the
zygospore originated develop a series of dichotomous processes in
close proximity to the walls which separate them from the zygospore.
These processes appear at first on one of the arcuate cells in
successive order. The first makes its appearance above upon the convex
side; the succeeding ones to the right and left in descending order;
the last is in the concavity beneath. It is only after the development
of this that the first process appears on the opposite cell, which is
followed by others in the same order. These dichotomous processes are
nothing more than branches developed from the arcuate, or mother
cells. During all these changes, while the zygospore enlarges, the
wall of the arcuate cells becomes coloured brown. This colouring is
more marked on the convex side, and it shows itself first in the cell
on which the dichotomous branches are first produced, and which
retains the darker tint longer than the other. The zone from whence
the processes issue, and also the processes themselves, have their
walls blackened deeply, while the walls of the conjugated cells, which
continue to clothe the zygospore during the whole of its development,
are bluish-black. By pressure, the thin brittle coat which envelopes
the zygospore is ruptured, and the coat of the zygospore exposed,
formed of a thick cartilaginous membrane, studded with large irregular
warts.

The germination of the zygospores in this species has not as yet been
observed, but it is probably the same or very