ucture from whence it
arises, and this, like the striae of diatoms, is very much an open
question. Mr. Currey held that the spiral appearance may be accounted
for by supposing the existence of an accurate elevation in the wall of
the cell, following a spiral direction from one end of the thread to
the other. This supposition would, he thinks, accord well with the
optical appearances, and it would account exactly for the undulations
of outline to which he alludes. He states that he had in his
possession a thread of _Trichia chrysosperma_, in which the spiral
appearance was so manifestly caused by an elevation of this nature, in
which it is so clear that no internal spiral fibre exists, that he did
not think there could be a doubt in the mind of any person carefully
examining it with a power of 500 diameters that the cause of the
spiral appearance was not a spiral fibre. In _Arcyria_, threads of a
different kind are present; they mostly branch and anastomose, and are
externally furnished with prominent warts or spines, which Mr.
Currey[W] holds are also arranged in a spiral manner around the
threads. In other Myxogastres, threads are also present without any
appreciable spiral markings or spines. In the mature condition of
these fungi, they so clearly resemble, and have such close affinities
with, the Trichogastres that one is led almost to doubt whether it was
not on hasty grounds, without due examination or consideration, that
proposals were made to remove them from the society of their kindred.

[Illustration: FIG. 11.--_Arcyria incarnata_, with portion of threads and
spore, magnified.]

Very little is known of the development of the spores in this group;
in the early stages the whole substance is so pulpy, and in the latter
so dusty, whilst the transition from one to the other is so rapid,
that the relation between the spores and threads, and their mode of
attachment, has never been definitely made out. It has been supposed
that the spinulose projections from the capillitium in some species
are the remains of pedicels from which, the spores have fallen, but
there is no evidence beyond this supposition in its favour, whilst on
the other hand, in _Stemonitis_, for instance, there is a profuse
interlacing capillitium, and no spines have been detected. In order to
strengthen the supposition, spines should be more commonly present.
The threads, or capillitium, form a beautiful reticulated network in
_Stemonitis_, _Cribra