venation of leaves.

Mine host with whom I lodged had a microscopical mount of the
Protococcus nivalis in excellent state of preservation. The sporangia
were very red and beautiful, but they showed no double cell wall.

In this locality ague is unknown; indeed, the place is one of unusual
salubrity. It is interesting to note here to show how some of the algae
are diffused. I found here an artificial pond fed by a spring, and
subject to overflow from another pond in spring and winter. A stream of
living water as large as one's arm (adult) feeds this artificial pond,
still it was crowded with the Clathrocyotis aeruginosa of some writers
and the Polycoccus of Reinsch. How it got there has not yet been
explained.

The migration of the ague eastward is a matter of great interest; it
is to be hoped that the localities may be searched carefully for your
plants, as I did in New Haven.

In this connection I desire to say something about the presence of the
Gemiasmas in the Croton water. The record I have given of finding
the Gemiasma verdans is not a solitary instance. I did not find the
gemiasmas in the Cochituate, nor generally in the drinking waters of
over thirty different municipalities or towns I have examined during
several years past. I have no difficulty in accounting for the presence
of the Gemiasmas in the Croton, as during the last summer I made studies
of the Gemiasma at Washington Heights, near 165th St. and 10th Ave.,
N.Y.

Plate VIII. is a photograph of a drawing of some of the Gemiasmas