The substance of clayish soil contains, besides fragments of shells of
larger diatoms (Suriella synhedra), shells of Navicula minutissima,
Pinnularia viridis. Spores belonging to various cryptogams.

1. Spherical transparent spores with laminated covering and dark
nucleus--0.022 millimeter in diameter.

2. Spherical spores with thick covering of granulated surface.

3. Spherical spores with punctulated surface--0.007 millimeter in
diameter.

4. Very minute, transparent, bluish-greenish colored spores, with thin
covering and finely granulated contents--0.006 millimeter in diameter.

5. Chroococcoid cells with two larger nuclei--0.0031 millimeter in
diameter. Sometimes biciliated minute cells are found; without any doubt
they are zoospores derived from any algoid or fungoid species.

I cannot say whether there exists any genetic connection between these
various sorts of spores. It seems to me that probably numbers 1-4
represent resting states of the hyphomycetes.

No. 5 represents one and two celled states of chroococcus species belong
to Chroococcus minutus.

The crust of the clayish earth is covered with a reddish brown covering
of about half a millimeter in thickness. This covering proves to be
composed, under the microscope, of cellular filaments and various shaped